There is high confidence that increasing ocean temperatures, changes in ocean acidity, and changes in the frequency and intensity of storms are extremely likely to affect coastal and marine resources. Large storm events within the past decade have resulted in significant effects on marine resources, particularly coral habitats and organisms that rely on them. There is medium confidence in predictions that coral habitats will likely continue to decline throughout the Caribbean, with associated effects on resources dependent on these habitats; although, scientific studies are still needed in terms of climate change effects on fisheries resources, particularly for species that are found in offshore waters or are pelagic. Changes in coral habitats are already occurring as evidenced by massive coral bleaching events (including a three-year global-level bleaching event from 2015–2017) and the increase in these events. Such changes in bleaching events are due to rising sea surface temperatures. There is high confidence that there have been changes in ocean pH and medium confidence on the ecological effects. Due to the lack of studies on the social consequences of climate change and associated losses of resources such as fisheries, there is medium confidence that effects on coastal and marine resources resulting from climate change will affect island economies. These effects can be a result of changes in availability and condition of fishery resources, loss of reefs and other coral communities that serve as coastal barriers, and effects on tourism due to loss of the resources that are primary attractions for visitors.
There is medium confidence in the ecological effects that will result due to changes in ocean pH. The CO2 system of seawater is well understood and established. As such, the understanding of the basic equilibria governing the process of ocean acidification dates back to at least 1960{{< tbib '168' 'b20e8c2b-cfb8-48b6-85c6-c981c361e267' >}} and represents a foundational understanding of modern chemical oceanography. The ecological consequences of human-induced changes to the system (that is, ocean acidification) is, however, a considerably new field. Both themes were assessed considering recent findings and based on adequate observed local data (for example, atmospheric pCO2 [carbon dioxide partial pressure] values are based on measurements of weekly air samples from St. Croix, the USVI, the United States, and Ragged Point, Barbados), complemented with empirical models. Projected changes in climate for the Caribbean islands were based on the future projections of fossil fuel emissions driven by reasonable models from the Intergovernmental Panel on Climate Change (IPCC).{{< tbib '169' 'bc140b4c-c2d9-4d99-a684-5c054dc5134f' >}} Additional empirical species response data would be useful for increasing the understanding of expected effects of ocean acidification on species and habitats in the Caribbean.
" evidence: "In 2006, the National Marine Fisheries Service (NMFS) listed elkhorn and staghorn corals as threatened species under the Endangered Species Act, with persistent elevated sea surface temperatures and sea level rise being two of the key factors influencing the listing decision.{{< tbib '158' '9d974b61-97ea-4778-977d-26701052c8e9' >}} The Acropora Biological Review Team (2005) found that the number of hurricanes affecting reef ecosystems in the Caribbean has increased over the past two decades (2 hurricanes in the 1970s, 6 in the 1980s, and 12 in the 1990s). Sea surface temperature is expected to continue rising, and this implies an increasing threat to elkhorn and staghorn corals from bleaching-induced mortality and possibly an exacerbation of disease effects. In 2014, NMFS listed an additional 5 species of Atlantic/Caribbean corals (lobed, mountainous star, boulder star, pillar, and rough cactus) as threatened and reevaluated the listing of elkhorn and staghorn corals, confirming them as threatened species; it also listed 15 Indo-Pacific coral species as threatened,{{< tbib '159' '8960de56-9b32-4544-9255-046a9ef45e0d' >}} with two of the key factors being ocean warming and ocean acidification. Brainard et al.{{< tbib '159' '8960de56-9b32-4544-9255-046a9ef45e0d' >}} found that ocean warming and related effects of climate change have already created a clear and present threat to many corals that will likely continue into the future and can be assessed with certainty out to 2100. Increases in human population densities and activity levels in the coastal zone are expected to continue, meaning the vulnerability of these populations and infrastructure will likely continue increasing with climate change.{{< tbib '160' '895e2c92-d614-4154-8509-7689918c8697' >}} Direct measurements at the Bermuda Atlantic Time-series Study station shows that surface ocean acidity has increased by about 12% and aragonite saturation (Ωarg) has decreased by about 8% over the past three decades.{{< tbib '161' 'ade3d353-6612-4e45-96d3-9269de56eda0' >}} These values agreed with those reported across the Caribbean{{< tbib '162' '0e312df5-ad3d-4709-8b58-8cea86d26415' >}} and Atlantic regions{{< tbib '18' 'd51156cc-0034-4afc-b2b7-1ad99efde458' >}},{{
Many coastal regions already experience low surface seawater pH and Ωarg conditions (localized or coastal ocean acidification) due to processes other than CO2 uptake. As a result, the effect of ocean acidification on coastal zones can be several times higher and faster than typically expected for oceanic waters.{{< tbib '163' 'dc5e5365-8b0f-4a21-93b4-c6a822be824d' >}}
Caribbean coral reefs in the Bahamas, Belize, Bonaire, and Grand Cayman are already experiencing significant reductions in carbonate production rates, with 37% of surveyed sites showing net erosion.{{< tbib '164' '0841a7ce-1022-4cf7-be4f-5c20d3b19f2a' >}} Friedrich et al. (2012).{{< tbib '66' 'a03f3916-2084-4353-bce4-adac93801617' >}} concluded that calcification rates may have already dropped by about 15% within the Caribbean with respect to their preindustrial values.
" href: https://data.globalchange.gov/report/nca4/chapter/us-caribbean/finding/key-message-20-2.yaml identifier: key-message-20-2 ordinal: 2 process: 'The majority of our Key Messages were developed over the course of two separate author meetings. The first occurred March 9–10, 2017, and the second on May 3, 2017. Both meetings were held in San Juan, Puerto Rico; however, people were also able to join remotely from Washington, DC, Raleigh, North Carolina, and the U.S. Virgin Islands (USVI). In addition, the author team held weekly conference calls and organized separate Key Message calls and meetings to review and draft information that was integral to our chapter. To develop the Key Messages, the team also deliberated with outside experts who are acknowledged as our technical contributors.
Marine ecological systems provide key ecosystem services such as commercial and recreational fisheries and coastal protection. These systems are threatened by changes in ocean surface temperature, ocean acidification, sea level rise, and changes in the frequency and intensity of storm events. Degradation of coral and other marine habitats can result in changes in the distribution of species that use these habitats and the loss of live coral cover, sponges, and other key species (very likely, high confidence). These changes will likely disrupt valuable ecosystem services, producing subsequent effects on Caribbean island economies (likely, medium confidence).
' uncertainties: "The link between climate stressors such as increasing sea surface temperatures and bleaching response and increasing prevalence of disease in corals is postulated. There is some scientific evidence indicating a link, but it is hard to make definitive conclusions. Effects of climate change on fisheries in the Caribbean have not been as well studied as the effects on marine habitats, particularly coral reefs.{{< tbib '74' '94f95306-0dd9-43cf-8e70-9a379423f31d' >}},{{
Uncertainty with respect to ocean acidification is dominated by uncertainty about how ecosystems and organisms will respond, particularly due to multiple interactions with other stressors.
The value of the loss of ecosystem services to ocean acidification is unknown. Such losses are attributable to the degradation of ecosystems that support important economic marine species such as coral, conch, oysters, fish larvae, urchins, and pelagic fish in the Caribbean. There is strong evidence for decreasing carbonate production, calcification rates, coral cover, and biomass of major reef-building species throughout the Caribbean region. However, there is still not enough evidence to conclude that all these decreased ecosystem processes are due to ocean acidification.
There are only a few studies on ecosystem and organism responses to climate stressors (such as ocean warming) that consider ocean acidification in the Caribbean. For instance, low pH values could affect nursery areas of commercially important species such as tuna, presenting a source of vulnerability for the economy, but studies are scarce. Ocean acidification could also affect the food web dynamics at lower trophic levels and have physiological effects at larval stages that would likely cascade upward, affecting coral and fish recruitment.
The effects of ocean acidification on coral reefs, shellfish, fish, and marine mammals will likely cause an economic effect on fisheries, coastal protection, and tourism in the Caribbean. Ocean acidification can exacerbate the current global warming effects on coral reefs, and it will likely continue deteriorating reef conditions and cause ecological regime shifts from coral to algal reefs.{{< tbib '77' 'b09adbe5-6a17-4d3c-ab96-b3d9e306af67' >}},{{
Sea level rise is currently the most immediate and well-understood climate-related threat to mangroves.{{< tbib '70' 'c527429c-5661-477a-a6f4-1690355bcbd5' >}} It is not clear how mangroves will respond to elevated CO2, and some studies suggest increases may actually be beneficial to mangroves.{{< tbib '70' 'c527429c-5661-477a-a6f4-1690355bcbd5' >}} Similarly, in the Caribbean where temperatures are already high, increasing temperatures, as well as declines in rainfall and corresponding increases in soil salinity during periods of drought, will likely increase plant water stress and reduce productivity. There have been limited studies on the effects of climate change on seagrass beds; therefore, these effects remain uncertain.{{< tbib '69' '63aac7f9-5e82-4aff-ab62-75c12537612f' >}} Sea level rise that results in reduced sunlight due to increased water depths can lead to the loss of seagrass beds from deeper waters. As discussed previously, the loss or degradation of these habitats, which are part of the coral reef ecosystem and serve as nursery habitat for important nursery species, will likely contribute to declines in fishery productivity due to climate change.
" uri: /report/nca4/chapter/us-caribbean/finding/key-message-20-2 url: ~ - chapter_identifier: us-caribbean confidence: 'Sea levels have already risen and will likely continue to rise in the future. Based on current levels of greenhouse gas emissions, glacial melt, and ice sheet loss, there is high confidence and likelihood in these sea level rise projections.
' evidence: "The Key Message and subsequent narrative text are based on the best available information for the U.S. Caribbean. There are not many studies on or projections for sea level rise for the U.S. Caribbean. Therefore, evidence of sea level rise used for this report comes from the U.S. Army Corps of Engineers’ (USACE) Sea Level Change Curve Calculator.{{< tbib '95' 'b46d7ec8-76b0-4469-bc00-9348475efd0f' >}} To calculate the Intermediate and High scenarios, the USACE uses modified National Research Council (NRC) curves, the most recent IPCC projections, and modified NRC projections with local rate of vertical land movement.{{< tbib '95' 'b46d7ec8-76b0-4469-bc00-9348475efd0f' >}} The four NOAA estimates integrate data ranging from tide gauge records for the lowest scenario to projected ocean warming from the IPCC’s global sea level rise projections combined with the maximum projection for glacier and ice sheet loss for 2100 for the highest scenario. The sea level rise analysis mainly focuses on data from two tide gauges chosen to be representative of the region, one in San Juan, Puerto Rico, and the other in Charlotte Amalie, USVI. There are two others in the region that provide sea level trend data located in Magueyes, Puerto Rico, and Lime Tree Bay, USVI.
Additional evidence that sea level is rising is well documented in Chapter 9: Oceans and in the Climate Science Special Report. There are also numerous empirical examples of sea level rise and its effects in Puerto Rico and the USVI, where beaches have been reduced by erosion, roads have been lost, and access to schools has been affected.
" href: https://data.globalchange.gov/report/nca4/chapter/us-caribbean/finding/key-message-20-3.yaml identifier: key-message-20-3 ordinal: 3 process: 'The majority of our Key Messages were developed over the course of two separate author meetings. The first occurred March 9–10, 2017, and the second on May 3, 2017. Both meetings were held in San Juan, Puerto Rico; however, people were also able to join remotely from Washington, DC, Raleigh, North Carolina, and the U.S. Virgin Islands (USVI). In addition, the author team held weekly conference calls and organized separate Key Message calls and meetings to review and draft information that was integral to our chapter. To develop the Key Messages, the team also deliberated with outside experts who are acknowledged as our technical contributors.
Coasts are a central feature of Caribbean island communities. Coastal zones dominate island economies and are home to critical infrastructure, public and private property, cultural heritage, and natural ecological systems. Sea level rise, combined with stronger wave action and higher storm surges, will worsen coastal flooding and increase coastal erosion (very likely, very high confidence), likely leading to diminished beach area (likely, high confidence), loss of storm surge barriers (likely, high confidence), decreased tourism (likely, medium confidence), and negative effects on livelihoods and well-being (likely, medium confidence). Adaptive planning and nature-based strategies, combined with active community participation and traditional knowledge, are beginning to be deployed to reduce the risks of a changing climate.
' uncertainties: 'Sea level rise is already occurring. However, the uncertainty lies in how much of an increase will take place in the future and how coastal social and ecological systems will respond. There are various models and projections to estimate this number, but it is influenced by many unknown factors, such as the amount of future greenhouse gas emissions and how quickly glaciers and ice sheets melt. Another major uncertainty lies in humans’ abilities to combat or adapt to these changes. The scale at which people and cities will be affected depends on the actions taken to reduce risk. Lastly, the experience of sea level rise on each coast and community is different, depending on land subsidence or accretion, land use, and erosion; thus, the severity of effects might differ based on these factors.
Due to the levels of uncertainty surrounding the projections, we focused much attention on the highest scenarios, as fewer consequences exist for planning in terms of the higher scenario (RCP8.5).
' uri: /report/nca4/chapter/us-caribbean/finding/key-message-20-3 url: ~ - chapter_identifier: us-caribbean confidence: 'There is high confidence that increasing temperatures threaten the health and well-being of people living in the U.S. Caribbean, especially in high-density urban areas where the UHI effect places further stress on city populations.
' evidence: 'In warm tropical areas like Puerto Rico and the USVI, higher summertime temperatures mean more energy is needed to cool buildings and homes, increasing the demand for energy. Heat episodes are becoming more common worldwide, including in tropical regions like the U.S. Caribbean. Higher frequency, duration, and intensity of heat episodes are triggering serious public health issues in San Juan. Heat poses a greater threat to health and well-being in high-density urban areas. Land use and land cover have affected local climate directly and indirectly, facilitating the urban heat island (UHI) effect, with potential effects on heat-related morbidity and mortality among urban populations.
' href: https://data.globalchange.gov/report/nca4/chapter/us-caribbean/finding/key-message-20-4.yaml identifier: key-message-20-4 ordinal: 4 process: 'The majority of our Key Messages were developed over the course of two separate author meetings. The first occurred March 9–10, 2017, and the second on May 3, 2017. Both meetings were held in San Juan, Puerto Rico; however, people were also able to join remotely from Washington, DC, Raleigh, North Carolina, and the U.S. Virgin Islands (USVI). In addition, the author team held weekly conference calls and organized separate Key Message calls and meetings to review and draft information that was integral to our chapter. To develop the Key Messages, the team also deliberated with outside experts who are acknowledged as our technical contributors.
Natural and social systems adapt to the temperatures under which they evolve and operate. Changes to average and extreme temperatures have direct and indirect effects on organisms and strong interactions with hydrological cycles, resulting in a variety of impacts. Continued increases in average temperatures will likely lead to decreases in agricultural productivity, changes in habitats and wildlife distributions, and risks to human health, especially in vulnerable populations. As maximum and minimum temperatures increase, there are likely to be fewer cool nights and more frequent hot days, which will likely affect the quality of life in the U.S. Caribbean. (High Confidence)
' uncertainties: "Warming is evident. A remaining scientific question is how ecological and social systems that have established themselves in a particular location can adapt to higher average temperatures.{{< tbib '170' 'fd10f97c-39c6-4f3a-8306-aead1a368908' >}} Islands such as Puerto Rico are particularly vulnerable because of heat events associated with changes in both terrestrial and marine conditions. Although there is evidence suggesting that mortality relative to risk increases in San Juan due to extreme heat,{{< tbib '12' 'cb5c02d3-6e9e-4dc5-8eaa-b87f57030bbf' >}} this association is not completely understood on tropical islands like Puerto Rico and the USVI. Addressing such hazards can benefit from new strategies that seek to determine linkages between human health, rapid and synoptic environmental monitoring, and the research that helps improve the forecast of hazardous conditions for particular human population segments or for other organisms.
" uri: /report/nca4/chapter/us-caribbean/finding/key-message-20-4 url: ~ - chapter_identifier: us-caribbean confidence: 'There is high confidence that increasing frequency of extreme events threatens life, property, and economy in the region, given that the U.S. Caribbean’s vulnerable populations and fragile economies are continually exposed to climate extremes. There is medium confidence that the frequency and intensity of the most extreme hurricanes and droughts will likely increase. There is high confidence that extreme events will likely continue to affect human health and well-being, economic development and tourism, conservation, agriculture, and danger from flooding. There is high confidence that future recovery and cultural continuity will depend on significant and integrated resilience planning across the region, focusing on collaborative actions among stakeholders.
' evidence: "On both Puerto Rico and the USVI, disaster events have caused billions of dollars in property and crop damages.{{< tbib '171' 'cdbb39c1-4de9-4067-8ebc-24de32b50b57' >}} Over the years, disaster-induced casualties have declined in both territories. Tropical cyclones, particularly hurricanes, continue to generate the most severe economic damage across the U.S. Caribbean. Floods and droughts are challenging to manage for both territories, and these challenges may be exacerbated by climate change induced shifts in precipitation regimes.
Climate modeling for tropical cyclone activity in the Atlantic Basin, including the Caribbean region, points toward an increase in the frequency of more intense hurricanes.{{< tbib '135' '349482df-4a77-4802-8b39-14d5e63b946f' >}} An increase in days with more than 3 inches of rain per 24-hour period is projected for Puerto Rico, based on statistically downscaled CMIP3 climate models.{{< tbib '28' '56d77153-c8fc-4fcf-a7f0-fa0e843936f1' >}} Changes in precipitation patterns are expected for Puerto Rico in the periods 2030–2050 and 2100, pointing toward an overall decrease in mean precipitation for different climate change scenarios.{{< tbib '7' '650b2907-85b1-4b76-a339-a9ec1703c5bd' >}},{{
While continental droughts typically affect vast regions, droughts affecting Puerto Rico and the USVI tend to vary significantly in extent and severity over smaller distances.{{< tbib '132' 'edd9a004-f859-41ae-9f93-80201c4ffd65' >}} Statistically downscaled climate projections for Puerto Rico suggest an increase of drought intensity (measured as the total annual dry days) and extremes (measured as the annual maximum number of consecutive dry days) due to an increase in mean and extreme temperatures and a decrease in precipitation.{{< tbib '7' '650b2907-85b1-4b76-a339-a9ec1703c5bd' >}}
An increase in mean atmospheric temperature has been observed across the U.S. Caribbean islands, particularly on Puerto Rico. An analysis of the observed temperatures across several NOAA weather stations in Puerto Rico showed rising temperature trends between 1970 and 2016.{{< tbib '172' 'e8d32931-3301-45c8-bfe7-b8e8b9fff6b6' >}} Following the principles established by the international Expert Team on Climate Change Detection and Indices,{{< tbib '173' 'e6ecbe14-fe1b-46f8-bad5-bde9e4cc658a' >}} temperature extremes and trends were identified, indicating significant increases in rising annual temperatures and an increase in extreme heat episodes.
" href: https://data.globalchange.gov/report/nca4/chapter/us-caribbean/finding/key-message-20-5.yaml identifier: key-message-20-5 ordinal: 5 process: 'The majority of our Key Messages were developed over the course of two separate author meetings. The first occurred March 9–10, 2017, and the second on May 3, 2017. Both meetings were held in San Juan, Puerto Rico; however, people were also able to join remotely from Washington, DC, Raleigh, North Carolina, and the U.S. Virgin Islands (USVI). In addition, the author team held weekly conference calls and organized separate Key Message calls and meetings to review and draft information that was integral to our chapter. To develop the Key Messages, the team also deliberated with outside experts who are acknowledged as our technical contributors.
Extreme events pose significant risks to life, property, and economy in the Caribbean, and some extreme events, such as flooding and droughts, are projected to increase in frequency and intensity (flooding as likely as not, medium confidence; droughts very likely, medium confidence). Increasing hurricane intensity and associated rainfall rates (likely, medium confidence) will likely affect human health and well-being, economic development, conservation, and agricultural productivity. Increased resilience will depend on collaboration and integrated planning, preparation, and responses across the region (high confidence).
' uncertainties: "There are still uncertainties as to how these projected changes in tropical Atlantic cyclone activity will affect the frequency distribution of extreme precipitation events. While an increase in days with more than 3 inches of rain per 24-hour period has been projected based on statistically downscaled CMIP3 models,{{< tbib '28' '56d77153-c8fc-4fcf-a7f0-fa0e843936f1' >}} more recent generations of GCMs do not show this increase in extreme rainfall events, and this adds uncertainty. Results from two dynamically downscaled climate models using the most recent generation of GCMs for the region do not show increases in the frequency of extreme events.{{< tbib '34' '744497bd-974c-497e-bf74-34ff514c0f83' >}}
At present, data pertaining to the costs and effects that are associated with extreme events and disasters are very limited and not readily accessible for government officials, disaster risk managers, or the general public. In the future, more accessible data could facilitate opportunities for more thorough analyses on the economic costs of extreme events for the U.S. Caribbean.
" uri: /report/nca4/chapter/us-caribbean/finding/key-message-20-5 url: ~ - chapter_identifier: us-caribbean confidence: 'There is high confidence that climate change will likely result in serious water supply shortages and in increased risks for agriculture production, human health, wildlife, and the socioeconomic development of Puerto Rico, the USVI, and the wider Caribbean region. The effects of climate change in the Caribbean region are likely to increase threats to life and infrastructure from sea level rise and extreme events; reduce the availability of fresh water, particularly during the dry season; negatively affect coral reef ecosystems; and cause health problems due to high temperatures and an increase in diseases.
' evidence: "Cross-regional and international cooperation is a mechanism that will likely reduce climate vulnerability and risks in the U.S. Caribbean, because it builds capacity and leverages resources in a region that has low adaptive capacity, due in part to the high costs of mitigation and adaptation relative to gross domestic product.{{< tbib '1' '63e4948c-5b46-4deb-a37b-9f363a1a8316' >}},{{
The majority of our Key Messages were developed over the course of two separate author meetings. The first occurred March 9–10, 2017, and the second on May 3, 2017. Both meetings were held in San Juan, Puerto Rico; however, people were also able to join remotely from Washington, DC, Raleigh, North Carolina, and the U.S. Virgin Islands (USVI). In addition, the author team held weekly conference calls and organized separate Key Message calls and meetings to review and draft information that was integral to our chapter. To develop the Key Messages, the team also deliberated with outside experts who are acknowledged as our technical contributors.
Shared knowledge, collaborative research and monitoring, and sustainable institutional adaptive capacity can help support and speed up disaster recovery, reduce loss of life, enhance food security, and improve economic opportunity in the U.S. Caribbean. Increased regional cooperation and stronger partnerships in the Caribbean can expand the region’s collective ability to achieve effective actions that build climate change resilience, reduce vulnerability to extreme events, and assist in recovery efforts (very likely, high confidence)
' uncertainties: 'There is high certainty that Caribbean island states are being affected by climate change, but the rate and degree of effects vary across countries due to the differences in environmental and socioeconomic conditions. Examples of regional cooperation efforts to share knowledge, conduct collaborative research, and develop joint projects have increased the adaptive capacity in the region; however, sustaining such efforts across the region remains a challenge. As efforts for regional coordination, cooperation, and information exchange evolve, evidence of the benefits of collaboration can be better assessed.
' uri: /report/nca4/chapter/us-caribbean/finding/key-message-20-6 url: ~ - chapter_identifier: midwest confidence: 'There is very high confidence that increases in warm-season absolute humidity and precipitation very likely have eroded soils, created favorable conditions for pests and pathogens, and degraded quality of stored grain. There is medium confidence that projected increases in moisture, coupled with rising mid-summer temperatures, likely will be detrimental to crop and livestock production and put future gains in commodity grain production at risk by mid-century. Projected changes in precipitation, coupled with rising extreme temperatures, provide medium confidence that by mid-century Midwest agricultural productivity likely will decline to levels of the 1980s without major technological advances.
' evidence: "Humidity is increasing. Feng et al. (2016){{< tbib '3' '28675f8a-8858-40ac-b53a-710b489bca07' >}} show plots of trends in surface and 850 hPa specific humidity of 0.4 and 0.2 g/kg/decade, respectively, from 1979–2014 for the April–May–June period across the Midwest. These represent increases of approximately 5% and 3% per decade, respectively. Automated Surface Observing Stations in Iowa{{< tbib '320' '9dc60b30-9bb1-46c8-aaea-9dba602c2d05' >}} having dew point records of this length and season show dew point temperature increases of about 1°F per decade. Brown and DeGaetano (2013){{< tbib '49' '83d23b83-2a04-4a6b-bdfa-caa8b54b1ccf' >}} show increasing dew points in all seasons throughout the Midwest. Observed changes in annual average maximum temperature for the Midwest over the 20th century (Vose et al. 2017,{{< tbib '54' '29960c69-6168-4fb0-9af0-d50bdd91acd3' >}} Table 6.1) have been less than 1°F. However, future projected changes in annual average temperature (Vose et al. 2017,{{< tbib '54' '29960c69-6168-4fb0-9af0-d50bdd91acd3' >}} Table 6.4), as well as in both warmest day of the year and warmest 5-day 1-in-10 year events (Vose et al. 2017,{{< tbib '54' '29960c69-6168-4fb0-9af0-d50bdd91acd3' >}} Table 6.5), are higher for the Midwest than in any other region of the United States.
Garbrecht et al. (2007){{< tbib '321' '232aa0b0-6c75-46f6-90df-85b58cfbb3b1' >}} state that precipitation changes are sufficient to require U.S. policy changes for agricultural lands. The Soil Erosion Site (http://soilerosion.net/water_erosion.html) describes the soil erosion process and provides links to soil erosion models.{{< tbib '322' '4baac62e-5892-4a0a-b435-e2cedc62f9a2' >}} Nearing et al. (2004){{< tbib '44' '43e7bfdb-30c7-407d-89ae-e94f7bff36a1' >}} report that global climate models project increases in erosivity (the ability or power of rain to cause soil loss) across the northern states of the United States over the 21st century.
Spoilage in stored grain is caused by mold growth and insect activity, which are related to the moisture content and temperature of the stored grain.{{< tbib '323' 'c65ba7e2-12f7-4a02-82c1-622c0aeb8711' >}} The ability of fungi to produce mycotoxins, including aflatoxin and fumonisins, is largely influenced by temperature, relative humidity, insect attack, and stress conditions of the plants.{{< tbib '57' '1ca7e70d-66b3-42e1-9a68-31b976d2622f' >}},{{
Germination of wheat declined in storage facilities where moisture level increased with time.{{< tbib '326' '5c614c37-2c94-413e-85d1-28d44b88d452' >}} Freshly harvested, high-moisture content grain must be dried to minimize (or prevent) excessive respiration and mold growth on grains.{{< tbib '327' '64513762-d666-447a-b19d-18bcd9cb0b80' >}} The storage life of grain is shortened significantly when stored at warm temperatures. One day of holding warm, wet corn before drying can decrease storage life by 50%.{{< tbib '45' '858d3935-f2b4-46d1-8c20-4fdf50922067' >}}
Feng et al. (2016){{< tbib '3' '28675f8a-8858-40ac-b53a-710b489bca07' >}} show humidity is rising in the Midwest in the warm season. Cook et al. (2008){{< tbib '4' 'e6bbc070-a723-4341-be6e-09bbd3248a20' >}} show that the factors leading to these humidity increases (warming Gulf of Mexico and strengthening of the Great Plains Low-Level Jet) will increase in a warming climate.
The ability of fungi to produce mycotoxins is largely influenced by temperature, relative humidity, insect attack, and stress conditions of the plants.{{< tbib '324' '2688cf64-d71f-4e21-84ad-f5cae499ed61' >}} More extreme rainfall events would favor formation of Deoxynivalenol, also known as vomitoxin.{{< tbib '57' '1ca7e70d-66b3-42e1-9a68-31b976d2622f' >}}
Hatfield et al. (2011,{{< tbib '50' 'a2704ef3-5be4-41ee-8dfa-4c82e416a292' >}} Table 1) give the relationships between temperature and vegetative function as well as reproductive capacity. This work was expanded and updated in Walthall et al. (2012).{{< tbib '328' '3baf471f-751f-4d68-9227-4197fdbb6e5d' >}}
Mader et al. (2010){{< tbib '74' '6a1bc03d-a204-4f8c-9779-73ee5c44e413' >}} report a comprehensive climate index for describing the effect of ambient temperature, relative humidity, radiation, and wind speed on environmental stress in animals. St-Pierre et al. (2003){{< tbib '329' 'ef0e1901-7533-4af4-b3b8-840a78ca4a49' >}} provide tables estimating economic losses in dairy due to reduced reproduction. The data show a strong gradient across the Midwest (with losses in Iowa, Illinois, and Indiana being three times the losses in Minnesota, Wisconsin, and Michigan under the current climate). Temperature and humidity increases projected for the Midwest will increase economic losses across the entire region. Lewis and Bunter (2010){{< tbib '330' '5eace42f-0819-4bec-a799-23c78ad4b486' >}} document heat stress effects of temperature on pig production and reproduction.
St-Pierre et al. (2003){{< tbib '329' 'ef0e1901-7533-4af4-b3b8-840a78ca4a49' >}} provide tables estimating economic losses in dairy, beef, swine, and poultry, resulting in declines from both meat/milk/egg production. The data show a strong gradient across the Midwest (with losses in Iowa, Illinois, and Indiana being twice the losses in Minnesota, Wisconsin, and Michigan under the current climate). Temperature and humidity increases projected for the Midwest will increase losses across the entire region. Babinszky et al. (2011){{< tbib '75' '3f7db557-5407-40cf-9078-d5be0f25ee0a' >}} identified temperature thresholds for meat/egg/milk production, beyond which performance declines. The adverse effects of heat stress include high mortality, decreased feed consumption, poor body weight gain and meat quality in broiler chickens, and poor laying rate, egg weight, and shell quality in laying hens.{{< tbib '76' '06f01e99-7afa-4be6-93ab-881cab8e56b8' >}}
Takle et al. (2013){{< tbib '65' '6e8fbacd-aff6-48ab-a950-5a8df2799046' >}} found that by mid-century, yields of corn and soybean are projected to fall well below projections based on extrapolation of trends since 1970 even under an optimistic economic scenario, with larger interannual variability in yield and total production. Liang et al. (2017){{< tbib '2' 'c5857041-2594-47cf-a6bc-3fab052fa903' >}} report that the ratio of measured agricultural output to measured inputs would drop by an average 3% to 4% per year under medium to high emissions scenarios and could fall to pre-1980 levels by 2050 even when accounting for present rates of innovation. Schauberger et al. (2017){{< tbib '66' '2967c8a9-063e-4118-92a4-71f266341e2f' >}} found that the impact of exposure to temperatures from 30°C to 36°C projected for the end of the century under RCP8.5 creates yield losses of 49% for maize and 40% for soybean.
According to Easterling et al. (2017),{{< tbib '193' 'e8089a19-413e-4bc5-8c4a-7610399e268c' >}} evidence suggests that droughts have become less frequent in the Midwest as the region has become wetter. However, they note that “future higher temperatures will likely lead to greater frequencies and magnitudes of agricultural droughts throughout the continental United States as the resulting increases in evapotranspiration outpace projected precipitation increases.
" href: https://data.globalchange.gov/report/nca4/chapter/midwest/finding/key-message-21-1.yaml identifier: key-message-21-1 ordinal: 1 process: "The chapter lead authors were identified in October 2016, and the author team was recruited in October and November 2016. Authors were selected for their interest and expertise in areas critical to the Midwest with an eye on diversity in expertise, level of experience, and gender. The writing team engaged in conference calls starting in December 2016, and calls continued on a regular basis to discuss technical and logistical issues related to the chapter. The Midwest chapter hosted an engagement workshop on March 1, 2017, with the hub in Chicago and satellite meetings in Iowa, Indiana, Michigan, and Wisconsin. The authors also considered other outreach with stakeholders, inputs provided in the public call for technical material, and incorporated the available recent scientific literature to write the chapter. Additional technical authors were added as needed to fill in the gaps in knowledge.
Discussion amongst the team members, along with reference to the Third National Climate Assessment and conversations with stakeholders, led to the development of six Key Messages based on key economic activities, ecology, human health, and the vulnerability of communities. In addition, care was taken to consider the concerns of tribal nations in the northern states of the Midwest. The Great Lakes were singled out as a special case study based on the feedback of the engagement workshop and the interests of other regional and sector chapters.
Interaction between the lakes and the atmosphere in the Great Lakes region (e.g., through ice cover, evaporation rates, moisture transport, and modified pressure gradients) is crucial to simulating the region’s future climate (i.e., changes in lake levels or regional precipitation patterns).{{< tbib '315' 'fe83e7d3-3f29-4aef-81ae-28abd70dda2e' >}},{{
The Midwest is a major producer of a wide range of food and animal feed for national consumption and international trade. Increases in warm-season absolute humidity and precipitation have eroded soils, created favorable conditions for pests and pathogens, and degraded the quality of stored grain (very likely, very high confidence). Projected changes in precipitation, coupled with rising extreme temperatures before mid-century, will reduce Midwest agricultural productivity to levels of the 1980s without major technological advances (likely, medium confidence).
' uncertainties: "Global and regional climate models do not simulate well the dynamical structure of mesoscale convective systems in the Midwest, which are the critical “end processes” that create intense precipitation from increasing amounts of moisture evaporated over the Gulf of Mexico and transported by low-level jets (LLJs) into the Midwest. Secondly, the strengthening of future LLJs depends on strengthening of both the Bermuda surface high pressure and the lee surface low over the eastern Rocky Mountains. Confirming simulations of this in future climates are needed. Global and regional climate models do simulate future scenarios having increasing temperatures for the region with high confidence (a necessary ingredient for increased humidity). There is uncertainty of the temperature thresholds for crops because, as pointed out by Schauberger et al. (2017),{{< tbib '66' '2967c8a9-063e-4118-92a4-71f266341e2f' >}} some negative impacts of higher temperatures can be overcome through increased water availability. Agricultural yield models, productivity models, and integrated assessment models each provide different ways of looking at agricultural futures, and each of these three types of models has high levels of uncertainty. However, all point to agriculture futures that fail to maintain upward historical trends.
" uri: /report/nca4/chapter/midwest/finding/key-message-21-1 url: ~ - chapter_identifier: midwest confidence: 'There is high confidence that the interactions of warming temperatures, precipitation changes, and drought with insect pests, invasive plants, and tree pathogens will likely lead to increased tree mortality of some species, reducing productivity of some forests. There is very high confidence that these interactions will very likely result in the decline of some economically or culturally important tree species. Additionally, there is high confidence that suitable habitat conditions for tree species will change as temperatures increase and precipitation patterns change, making it likely that forest composition will be altered and forest ecosystems may shift to new forest types. Due to uncertainties on species migration rates and forest management responses to climate changes, there is medium confidence that by the end of the century, some forest ecosystems are as likely as not to convert to non-forest ecosystems.
' evidence: "Multiple ecosystem vulnerability assessments that have been conducted for major forested ecoregions within the Midwest{{< tbib '89' '8b4159ec-1edb-4fab-8af5-10a8cdec8fb5' >}},{{
Significant indirect impacts to forests are expected as warming increases the negative effects of invasive plants, insect pests, and tree pathogens of forests.{{< tbib '105' '98e8338c-3c49-49f7-9334-d4c28a901ad0' >}},{{
Direct and indirect impacts of climate change may lead to the decline of culturally{{< tbib '88' '7e39f05f-d63f-473a-87c3-93d733ea178b' >}},{{
Many examples of land managers implementing climate adaptation in forest management exist, suggesting significant willingness to address the impacts of a changing climate across diverse land ownerships in managed forests{{< tbib '134' '7242780c-93ee-4a39-9505-d0bd2f67c62b' >}} and urban forests.{{< tbib '133' '6352c444-c49b-4dac-b375-2b72b8532ebe' >}} Forest management strategies to adapt to a changing climate highlight the importance of increasing forest diversity and managing for tree species adapted to a range of climate conditions.{{< tbib '8' '28ab77d2-73c7-4554-82ef-c8bd5e095887' >}} The importance of Traditional Ecological Knowledge for informing approaches for climate adaptation on tribal lands and within ceded territory is recognized.{{< tbib '331' '44b1444b-29ab-4edd-b285-f8820660fc32' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/midwest/finding/key-message-21-2.yaml identifier: key-message-21-2 ordinal: 2 process: "The chapter lead authors were identified in October 2016, and the author team was recruited in October and November 2016. Authors were selected for their interest and expertise in areas critical to the Midwest with an eye on diversity in expertise, level of experience, and gender. The writing team engaged in conference calls starting in December 2016, and calls continued on a regular basis to discuss technical and logistical issues related to the chapter. The Midwest chapter hosted an engagement workshop on March 1, 2017, with the hub in Chicago and satellite meetings in Iowa, Indiana, Michigan, and Wisconsin. The authors also considered other outreach with stakeholders, inputs provided in the public call for technical material, and incorporated the available recent scientific literature to write the chapter. Additional technical authors were added as needed to fill in the gaps in knowledge.
Discussion amongst the team members, along with reference to the Third National Climate Assessment and conversations with stakeholders, led to the development of six Key Messages based on key economic activities, ecology, human health, and the vulnerability of communities. In addition, care was taken to consider the concerns of tribal nations in the northern states of the Midwest. The Great Lakes were singled out as a special case study based on the feedback of the engagement workshop and the interests of other regional and sector chapters.
Interaction between the lakes and the atmosphere in the Great Lakes region (e.g., through ice cover, evaporation rates, moisture transport, and modified pressure gradients) is crucial to simulating the region’s future climate (i.e., changes in lake levels or regional precipitation patterns).{{< tbib '315' 'fe83e7d3-3f29-4aef-81ae-28abd70dda2e' >}},{{
Midwest forests provide numerous economic and ecological benefits, yet threats from a changing climate are interacting with existing stressors such as invasive species and pests to increase tree mortality and reduce forest productivity (likely, high confidence). Without adaptive actions, these interactions will result in the loss of economically and culturally important tree species such as paper birch and black ash (very likely, very high confidence) and are expected to lead to the conversion of some forests to other forest types (likely, high confidence) or even to non-forested ecosystems by the end of the century (as likely as not, medium confidence). Land managers are beginning to manage risk in forests by increasing diversity and selecting for tree species adapted to a range of projected conditions.
' uncertainties: 'There is significant uncertainty surrounding the ability of tree species migration rates to keep pace with changes in climate (based on temperature and precipitation) due to existing forest fragmentation and loss of habitat. Uncertainty in forest management responses, including active and widespread adaptation efforts that alter forest composition, add to the uncertainty of tree species movements. This leads to considerable uncertainty in the extent to which shifts in tree species ranges may lead to altered forest composition or loss of forest ecosystems in the future.
Due to the complex interactions among species, there is uncertainty in the extent that longer growing seasons, warming temperatures, and increased CO2 concentrations will benefit tree species, due to both limitations in available water and nutrients, as well as limited benefits for trees relative to the positive influences of these changes on stressors (invasives, insect pests, pathogens).
' uri: /report/nca4/chapter/midwest/finding/key-message-21-2 url: ~ - chapter_identifier: midwest confidence: 'In the Midwest, we already have seen very high levels of habitat loss and conversion, especially in grasslands, wetlands, and freshwater systems. This habitat degradation, in addition to the pervasive impacts of invasive species, pollution, water extraction, and lack of connectivity, all suggest that the adaptive capacity of species and systems is compromised relative to systems that are more intact and under less stress. Over time, this pervasive habitat loss and degradation has contributed to population declines, especially for wetland, prairie, and stream species. A reliance on cold surface-water systems, which often have compromised connectivity (due to dams, road-stream crossings with structures that impede stream flow, and other barriers) suggests that freshwater species, especially less mobile species like mussels, which are already rare, are at particular risk of declines and extinction. Due to the variety of life histories and climate sensitivities of species within the region, it is very challenging to specify what mechanisms will be most important in terms of driving change. However, knowing that drivers like invasive species, habitat loss, pollution, and hydrologic modifications promote species declines, it is very likely that the effects of climate change will interact, and we have very high confidence that these interactions will tend to increase, rather than decrease, stresses on species that are associated with these threats. While there is strong evidence that investments in restoring habitat can benefit species, we currently do not have strong observational evidence of the use of these new habitats, or benefits of restored wetlands, in response to isolated climate drivers. Thus, the confidence level for this statement is lower than for the first half of the message.
' evidence: "Changes in climate will very likely stress many species and ecological systems in the Midwest. As a result of increases in climate stressors, which typically interact with multiple other stressors, especially in the southern half of the Midwest region, both the ecological systems and the ecological services (water purification, pollination of crops and wild species, recreational opportunities, etc.) they provide to people are at risk. We draw from a wide range of national and global scale assessments of risks to biodiversity (e.g., Maclean and Wilson 2011, Pearson et al. 2014, and the review by Staudinger et al. 2013 that covered literature included in the Third National Climate Assessment{{< tbib '20' 'a0f111d8-ec32-486c-83a9-c9f359854550' >}},{{< tbib '18' 'b0d94572-aa34-47e0-bddf-0a8e7e0c60bb' >}},{{< tbib '22' '506759aa-765f-4007-a678-17d69d139e39' >}}), which all agree that on the whole, we are highly likely to see increases in species declines and extinctions as a result of climate change. It is very challenging to say specifically what combination of factors will drive these responses, but the weight of evidence suggests very high confidence in the overall trends. The link to interactions with other stressors is also very strong and is described in Brook et al. (2008){{< tbib '157' '5cee6e59-0713-4a56-abae-6f60119df8e5' >}} and Cahill et al. (2013),{{< tbib '17' '4da26e14-8c1a-4f66-8212-a98880263e91' >}} among others. Terrestrial ecosystem connectivity, thought to be important for the adaptive capacity of many species, is very low in the southern half of the Midwest region.{{< tbib '158' '3c96d70c-9523-49e8-b7aa-0a86be8992a0' >}},{{
The chapter lead authors were identified in October 2016, and the author team was recruited in October and November 2016. Authors were selected for their interest and expertise in areas critical to the Midwest with an eye on diversity in expertise, level of experience, and gender. The writing team engaged in conference calls starting in December 2016, and calls continued on a regular basis to discuss technical and logistical issues related to the chapter. The Midwest chapter hosted an engagement workshop on March 1, 2017, with the hub in Chicago and satellite meetings in Iowa, Indiana, Michigan, and Wisconsin. The authors also considered other outreach with stakeholders, inputs provided in the public call for technical material, and incorporated the available recent scientific literature to write the chapter. Additional technical authors were added as needed to fill in the gaps in knowledge.
Discussion amongst the team members, along with reference to the Third National Climate Assessment and conversations with stakeholders, led to the development of six Key Messages based on key economic activities, ecology, human health, and the vulnerability of communities. In addition, care was taken to consider the concerns of tribal nations in the northern states of the Midwest. The Great Lakes were singled out as a special case study based on the feedback of the engagement workshop and the interests of other regional and sector chapters.
Interaction between the lakes and the atmosphere in the Great Lakes region (e.g., through ice cover, evaporation rates, moisture transport, and modified pressure gradients) is crucial to simulating the region’s future climate (i.e., changes in lake levels or regional precipitation patterns).{{< tbib '315' 'fe83e7d3-3f29-4aef-81ae-28abd70dda2e' >}},{{
The ecosystems of the Midwest support a diverse array of native species and provide people with essential services such as water purification, flood control, resource provision, crop pollination, and recreational opportunities. Species and ecosystems, including the important freshwater resources of the Great Lakes, are typically most at risk when climate stressors, like temperature increases, interact with land-use change, habitat loss, pollution, nutrient inputs, and nonnative invasive species (very likely, very high confidence). Restoration of natural systems, increases in the use of green infrastructure, and targeted conservation efforts, especially of wetland systems, can help protect people and nature from climate change impacts (likely, high confidence).
' uncertainties: "There is significant uncertainty surrounding the ability of species and ecosystems to persist and thrive under climate change, and we expect to see many different types of responses (population increases, declines, local and regional extinctions).{{< tbib '17' '4da26e14-8c1a-4f66-8212-a98880263e91' >}} In some cases, climate change does have the potential to benefit species; for example, fish in the coldest regions of the Great Lakes (i.e., Lake Superior) are likely to show increases in productivity, at least in the short run.{{< tbib '332' '8a6a8c87-01dc-4370-a982-afe4207f1962' >}} However, as a whole, given the environmental context upon which climate change is operating, and the presence of many cold-adapted species that are close to the southern edge of their distributional range, we expect more declines than increases.
The last section of the Key Message focuses on land protection and restoration—conservation strategies intended to reduce the impacts of land-use change. Many modeling studies have called out loss of habitat in the Midwest as a key barrier to both local survival and species movement in response to climate change (Schloss et al. 2012 and Carroll et al. 2015 are two of the most recent{{< tbib '158' '3c96d70c-9523-49e8-b7aa-0a86be8992a0' >}},{{< tbib '158' '3c96d70c-9523-49e8-b7aa-0a86be8992a0' >}}). Restoring habitat can restore connectivity and protect key ecological functions like pollination services and water purification. Restoring wetlands also can help protect ecosystems and people from flooding, which is the rationale for the last line in the Key Message.
" uri: /report/nca4/chapter/midwest/finding/key-message-21-3 url: ~ - chapter_identifier: midwest confidence: 'Based on the evidence, there is very high confidence that climate change is very likely to impact midwesterners’ health.
' evidence: "There is strong evidence that increasing temperatures and precipitation in the Midwest will occur by the middle and end of the 21st century.{{< tbib '27' 'dd5b893d-4462-4bb3-9205-67b532919566' >}} The impacts of these changes on human health are broadly captured in the 2016 U.S. Global Change Research Program’s Climate and Health Assessment.{{< tbib '26' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} Air quality, including particulate matter and ground-level ozone, is positively associated with increased temperatures and has been well-documented to show deleterious impacts on morbidity and mortality.{{< tbib '231' '5ec155e5-8b77-438f-afa9-fbcac4d27690' >}} Likewise, increased temperatures have been shown in communities in the Midwest, as well as across the United States, to have substantial impacts on health and well-being.{{< tbib '232' 'dac369a3-921e-426f-b4a2-5798dfb9c515' >}},{{
Access to basic preventive care measures quantifiably reduces disease burden for climate-sensitive exposures.{{< tbib '238' '327a1728-7992-448b-9e5b-267328259994' >}},{{
The chapter lead authors were identified in October 2016, and the author team was recruited in October and November 2016. Authors were selected for their interest and expertise in areas critical to the Midwest with an eye on diversity in expertise, level of experience, and gender. The writing team engaged in conference calls starting in December 2016, and calls continued on a regular basis to discuss technical and logistical issues related to the chapter. The Midwest chapter hosted an engagement workshop on March 1, 2017, with the hub in Chicago and satellite meetings in Iowa, Indiana, Michigan, and Wisconsin. The authors also considered other outreach with stakeholders, inputs provided in the public call for technical material, and incorporated the available recent scientific literature to write the chapter. Additional technical authors were added as needed to fill in the gaps in knowledge.
Discussion amongst the team members, along with reference to the Third National Climate Assessment and conversations with stakeholders, led to the development of six Key Messages based on key economic activities, ecology, human health, and the vulnerability of communities. In addition, care was taken to consider the concerns of tribal nations in the northern states of the Midwest. The Great Lakes were singled out as a special case study based on the feedback of the engagement workshop and the interests of other regional and sector chapters.
Interaction between the lakes and the atmosphere in the Great Lakes region (e.g., through ice cover, evaporation rates, moisture transport, and modified pressure gradients) is crucial to simulating the region’s future climate (i.e., changes in lake levels or regional precipitation patterns).{{< tbib '315' 'fe83e7d3-3f29-4aef-81ae-28abd70dda2e' >}},{{
Climate change is expected to worsen existing conditions and introduce new health threats by increasing the frequency and intensity of poor air quality days, extreme high temperature events, and heavy rainfalls; extending pollen seasons; and modifying the distribution of disease-carrying pests and insects (very likely, very high confidence). By mid-century, the region is projected to experience substantial, yet avoidable, loss of life, worsened health conditions, and economic impacts estimated in the billions of dollars as a result of these changes (likely, high confidence). Improved basic health services and increased public health measures—including surveillance and monitoring—can prevent or reduce these impacts (likely, high confidence).
' uncertainties: 'While the modeling performed by the EPA was completed using the best available information, there is uncertainty around the extent to which biophysical adaptations will protect midwestern populations from heat-, air pollution-, aeroallergen-, and vector-related illness and death. Likewise, while there is a general consensus regarding habitat suitability for disease-carrying vectors in the eastern and western United States, the degree to which the disease burden may increase or decrease is largely uncertain.
' uri: /report/nca4/chapter/midwest/finding/key-message-21-4 url: ~ - chapter_identifier: midwest confidence: 'There is medium confidence that climate change is contributing to increased flood risk in the Midwest; there is medium confidence that green infrastructure is reducing flood risk. There is much uncertainty associated with specific numerical projections. This leads to medium confidence that costs will exceed $500 million. However, the EPA projections are sufficient to provide high confidence that increasing the capacity of existing storm water systems in order to maintain current levels of service would require significant expenditures on the part of urban sewer districts.
' evidence: "The patterns of increased annual precipitation, and the size and frequency of heavy precipitation events in the Midwest, are shown in numerous studies and highlighted in Melillo et al. (2014){{< tbib '27' 'dd5b893d-4462-4bb3-9205-67b532919566' >}} and Easterling et al. (2017).{{< tbib '193' 'e8089a19-413e-4bc5-8c4a-7610399e268c' >}} Increases in annual precipitation of 5% to 15% are reported across the Midwest region.{{< tbib '193' 'e8089a19-413e-4bc5-8c4a-7610399e268c' >}} In addition, both the frequency and the intensity of heavy precipitation events in the Midwest have increased since 1901.{{< tbib '193' 'e8089a19-413e-4bc5-8c4a-7610399e268c' >}}
For the early 21st century (2016–2045), both lower and higher scenarios (RCP4.5 and RCP8.5) indicate that average annual precipitation could increase by 1% to 5% across the Midwest, suggesting that the observed increases are likely to continue. By mid-century (2036–2065), both scenarios (RCP4.5 and RCP8.5) indicate precipitation increases of 1% to 5% in Missouri and Iowa and 5% to 10% increases in states to the north and east. By late century (2070–2089), precipitation is expected to increase by 5% to 15% over present day, with slightly larger increases in the higher scenario (RCP8.5). Model simulations suggest that most of these increases will occur in winter and spring over the 21st century. Similar to annual precipitation, the amounts from the annual maximum one-day precipitation events (a measure of heavy precipitation events) are projected to increase over time in the Midwest. The size of the events could increase by 5% to 15% by late century.{{< tbib '193' 'e8089a19-413e-4bc5-8c4a-7610399e268c' >}}
Gray literature documents that heavy rains in the Midwest are overwhelming storm water management systems, leading to property damage. Kenward et al. (2016){{< tbib '256' 'e9ccb2ed-ba08-43aa-8895-a21908f6d691' >}} provide examples of rain-related sewage overflows in the Midwest. These include an overflow of 681 million gallons during heavy rains in April 2015 in Milwaukee and an overflow of over 100 million gallons from December 26–28, 2015, in St. Louis. Winters et al. (2015){{< tbib '37' '0fe1cea1-aae3-4a35-b78f-61dcb5d6df49' >}} document that failure of storm water management systems in heavy rain leads to property damage, including basement backups.
The disruption of transportation networks by heavy precipitation in the Midwest has been documented by collecting contemporary news reports and by compiling state government reports. Posey (2016){{< tbib '338' 'd9754ccb-d173-4624-8e6a-1efb9a37b556' >}} relates that four storms between April 2013 and April 2014 forced evacuations or damaged cars in St. Louis, Missouri. In the same period, there were 18 flood-related closures on Missouri roads, a figure that excludes closures on small local roads. Flooding in May 2017 led to the closure of more than 400 roads across Missouri, a figure that again excludes local roads. Closed roadways included multiple stretches of Interstate 44, as well as sections of I-55, affecting interstate traffic between St. Louis and Memphis.{{< tbib '339' 'bb613b8d-1aae-425c-b4b5-5274d1460d42' >}} News reports document that the same stretch of I-44 was shut down during the floods of December 2015–January 2016.{{< tbib '340' '7529ed72-74b6-4f77-bf19-8aeeb1ab5ae0' >}}
Flood-related disruptions to Midwest barge and rail traffic in 2013 were documented by several articles in Journal of Commerce, a shipping trade magazine.{{< tbib '265' 'cad15039-4add-470a-bac2-adeb08e201c4' >}},{{
Although there is ample documentation of transportation systems in the Midwest being disrupted by floods in recent years, there is a lack of long-term time series data on disruptions with which to determine whether these incidents are becoming more frequent. Development of long-term data on transportation disruptions in the Midwest is a research need. It is clear that flood frequency and severity on major rivers in the Midwest have increased in recent decades, although additional research is needed on the relative contributions of climate change and land-use change to increases in flood risk.{{< tbib '344' 'aa980625-eab7-45f5-9bcb-d8dbbd36e6c7' >}},{{
The EPA estimated economic costs related to infrastructure and transportation in the Midwest, including costs associated with bridge scour and pavement degradation.{{< tbib '28' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}} The use of green infrastructure to reduce impacts associated with heavy precipitation is also documented in gray literature, including municipal planning documents. Using planted areas to absorb rainfall and reduce runoff has become a common approach to storm water management.{{< tbib '223' 'b71cbf27-2a1d-477e-9d0a-4d49b427ed47' >}},{{
The chapter lead authors were identified in October 2016, and the author team was recruited in October and November 2016. Authors were selected for their interest and expertise in areas critical to the Midwest with an eye on diversity in expertise, level of experience, and gender. The writing team engaged in conference calls starting in December 2016, and calls continued on a regular basis to discuss technical and logistical issues related to the chapter. The Midwest chapter hosted an engagement workshop on March 1, 2017, with the hub in Chicago and satellite meetings in Iowa, Indiana, Michigan, and Wisconsin. The authors also considered other outreach with stakeholders, inputs provided in the public call for technical material, and incorporated the available recent scientific literature to write the chapter. Additional technical authors were added as needed to fill in the gaps in knowledge.
Discussion amongst the team members, along with reference to the Third National Climate Assessment and conversations with stakeholders, led to the development of six Key Messages based on key economic activities, ecology, human health, and the vulnerability of communities. In addition, care was taken to consider the concerns of tribal nations in the northern states of the Midwest. The Great Lakes were singled out as a special case study based on the feedback of the engagement workshop and the interests of other regional and sector chapters.
Interaction between the lakes and the atmosphere in the Great Lakes region (e.g., through ice cover, evaporation rates, moisture transport, and modified pressure gradients) is crucial to simulating the region’s future climate (i.e., changes in lake levels or regional precipitation patterns).{{< tbib '315' 'fe83e7d3-3f29-4aef-81ae-28abd70dda2e' >}},{{
Storm water management systems, transportation networks, and other critical infrastructure are already experiencing impacts from changing precipitation patterns and elevated flood risks (medium confidence). Green infrastructure is reducing some of the negative impacts by using plants and open space to absorb storm water (medium confidence). The annual cost of adapting urban storm water systems to more frequent and severe storms is projected to exceed $500 million for the Midwest by the end of the century (medium confidence).
' uncertainties: "Although there is very high confidence that flood risk is increasing in the Midwest, there remains uncertainty about the relative contributions of climate change and land-use change. There is, however, sufficient evidence that changing precipitation patterns are leading to changes in hydrology in the Midwest,{{< tbib '351' 'c9d0a7e9-2bba-48cb-bd53-9e8c4209976d' >}},{{
While it is clear that flood frequency and severity on major rivers in the Midwest have increased in recent decades, it must be emphasized that the change in precipitation levels is not the only factor contributing to the increase in flood risk. Land-use change, particularly the destruction of floodplains by levee systems, has also been documented as a key contributor to increasing flood risk in the Midwest.{{< tbib '344' 'aa980625-eab7-45f5-9bcb-d8dbbd36e6c7' >}},{{
There is high confidence that communities in the Midwest will as likely as not be increasingly vulnerable to climate change impacts such as flooding, urban heat islands, and drought. Similarly, there is medium confidence that tribal nations in the Midwest are likely to be especially vulnerable because of their reliance on threatened natural resources for their cultural, subsistence, and economic needs. Due to limited documentation in the literature, there is medium confidence that integrating adaptation into planning processes will offer an opportunity to manage climate risk better. Finally, there is high confidence that developing knowledge for decision-making in cooperation with vulnerable communities and tribal nations will help to decrease sensitivity and build adaptive capacity.
' evidence: "Limited evidence in the scientific literature indicates that at-risk communities in the Midwest will be increasingly vulnerable to the impacts of climate change, including increased flooding resulting from increased variation in precipitation patterns and changing lake levels,{{< tbib '285' 'c9ef5059-729c-4701-ad9a-da15255bd5ca' >}} urban heat islands,{{< tbib '287' '34db2d46-ef90-43a4-99ab-40dae17afcce' >}} and an intensification of heat and drought (see also the impacts and associated references in the previous sections).{{< tbib '286' 'b228ac0d-7bf9-4391-99e7-5c598b9ce55e' >}}
Several recent survey reports{{< tbib '28' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}},{{
Gray literature,{{< tbib '293' '3c3cc09b-c2d7-4c52-bf8f-c064efa78e93' >}} survey reports,{{< tbib '32' 'b74c5cc9-2e40-4ad9-92aa-f2b02c7a4be7' >}} and scientific literature{{< tbib '292' '660ac034-1441-4d28-98e2-61c8c252348a' >}} point to a few initiatives to integrate adaptation into municipal planning processes and utilize participatory methodologies to evaluate and manage climate risk.
A growing body of research indicates that interaction between producers of climate information, intermediaries, and end users plays a critical role in increasing climate knowledge integration and use for adaptation in the Midwest.{{< tbib '224' '7b490de7-7bcd-4e31-b512-9deaa3a5eba7' >}},{{
The chapter lead authors were identified in October 2016, and the author team was recruited in October and November 2016. Authors were selected for their interest and expertise in areas critical to the Midwest with an eye on diversity in expertise, level of experience, and gender. The writing team engaged in conference calls starting in December 2016, and calls continued on a regular basis to discuss technical and logistical issues related to the chapter. The Midwest chapter hosted an engagement workshop on March 1, 2017, with the hub in Chicago and satellite meetings in Iowa, Indiana, Michigan, and Wisconsin. The authors also considered other outreach with stakeholders, inputs provided in the public call for technical material, and incorporated the available recent scientific literature to write the chapter. Additional technical authors were added as needed to fill in the gaps in knowledge.
Discussion amongst the team members, along with reference to the Third National Climate Assessment and conversations with stakeholders, led to the development of six Key Messages based on key economic activities, ecology, human health, and the vulnerability of communities. In addition, care was taken to consider the concerns of tribal nations in the northern states of the Midwest. The Great Lakes were singled out as a special case study based on the feedback of the engagement workshop and the interests of other regional and sector chapters.
Interaction between the lakes and the atmosphere in the Great Lakes region (e.g., through ice cover, evaporation rates, moisture transport, and modified pressure gradients) is crucial to simulating the region’s future climate (i.e., changes in lake levels or regional precipitation patterns).{{< tbib '315' 'fe83e7d3-3f29-4aef-81ae-28abd70dda2e' >}},{{
At-risk communities in the Midwest are becoming more vulnerable to climate change impacts such as flooding, drought, and increases in urban heat islands (as likely as not, high confidence). Tribal nations are especially vulnerable because of their reliance on threatened natural resources for their cultural, subsistence, and economic needs (likely, medium confidence). Integrating climate adaptation into planning processes offers an opportunity to better manage climate risks now (medium confidence). Developing knowledge for decision-making in cooperation with vulnerable communities and tribal nations will help to build adaptive capacity and increase resilience (high confidence).
' uncertainties: 'Limited research specific to the Midwest region contributes to uncertainty around the specific vulnerabilities of at-risk communities, including urban and rural communities and tribal nations. Though climate change planning and action in both Midwest cities and rural areas are underway, documentation remains low, few examples exist in the public literature of the failure or success of efforts to mainstream climate action into municipal governance, and attempts to assess vulnerabilities, especially in poor urban communities, frequently encounter climate justice barriers. Likewise, the number, scope, and nature of tribal adaptation plans remain undocumented, as does the degree of implementation of these plans and the manner in which Traditional Ecological Knowledge is incorporated.
' uri: /report/nca4/chapter/midwest/finding/key-message-21-6 url: ~ - chapter_identifier: northern-great-plains confidence: 'There is high confidence that temperatures will rise in the region, which will likely produce less snowfall and smaller mountain snowpacks. There is very high confidence in the downstream consequences of these changes.
' evidence: "Multiple lines of research have shown that as a result of its high aridity, changes in water availability in the Northern Great Plains region are highly sensitive to small changes in climate.{{< tbib '35' '8c567c0c-cc42-4372-94ea-7abf677704c6' >}},{{
Natural reservoirs, groundwater, and snowpack are at risk to varying degrees. Reservoir vulnerability was recently analyzed to assess sustainable pumping rates,{{< tbib '42' 'bbb70780-07ef-4083-a3ff-8dc8d33b1e62' >}} while snow and especially glaciers appear to be in steady decline in recent decades,{{< tbib '38' 'bb0be3c7-6d67-4281-9ff4-db244460b65a' >}} attributed to global climate warming{{< tbib '39' '760d96a6-ba98-4e20-8897-2989d8f0ae6f' >}} that is projected to continue.{{< tbib '145' '29dec54f-92a8-4543-93f1-941da4f4d750' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/northern-great-plains/finding/key-message-22-1.yaml identifier: key-message-22-1 ordinal: 1 process: 'The chapter lead (CL) and coordinating lead author (CLA) developed a list of potential contributing authors by soliciting suggestions from the past National Climate Assessment (NCA) author team, colleagues and collaborators throughout the region, and contributors to other regional reports. Our initial list of potential authors also included CL nominees submitted to the U.S. Global Change Research Program (USGCRP). The CL and CLA discussed the Northern Great Plains, which was part of the larger Great Plains region for the Third National Climate Assessment (NCA3), with each of these nominees and, as part of that discussion, solicited suggestions for other nominees. This long list of potential contributing authors was pared down by omitting individuals who could not contribute in a timely fashion, and the list was finalized after reconciliation against key themes within the region identified by past NCA authors, the CL and CLA, and contributing author nominees. The team of contributing authors was selected to represent the region geographically and thematically, but participants from some states who had agreed to contribute were eventually unable to do so. Others were unable to contribute from the start. The author team is mostly composed of authors who did not contribute to NCA3.
The CL and CLA, in consultation with past NCA authors and contributing author nominees, identified an initial list of focal areas of regional importance. The author team then solicited input from colleagues and regional experts (identified based on their deep ties to scientific and practitioner communities across the region) on their thoughts on focal areas. This list informed the agenda of a region-wide meeting held on February 22, 2017, with core locations in Fort Collins, Colorado, and Rapid City, South Dakota. The main purpose of this meeting was to seek feedback on the proposed list of focal areas. With this feedback, the author team was able to refine our focal areas to the five themes comprising the Key Messages of the Northern Great Plains regional chapter. Of these, recreation/tourism is a focus area that is new from NCA3.
' report_identifier: nca4 statement: 'Water is the lifeblood of the Northern Great Plains, and effective water management is critical to the region’s people, crops and livestock, ecosystems, and energy industry. Even small changes in annual precipitation can have large effects downstream (very high confidence); when coupled with the variability from extreme events, these changes make managing these resources a challenge (very high confidence). Future changes in precipitation patterns, warmer temperatures, and the potential for more extreme rainfall events are very likely to exacerbate these challenges (very likely, high confidence).
' uncertainties: "While there is high confidence in future increases in temperature, uncertainties exist as to the changes in precipitation and runoff. Perhaps most important are the uncertainties in the degree of precipitation variability from year to year and within season (based on information dating to the 1950s).{{< tbib '35' '8c567c0c-cc42-4372-94ea-7abf677704c6' >}},{{
Uncertainties exist in agricultural demands for water, reservoir operation protocols, and changes in extreme events.
" uri: /report/nca4/chapter/northern-great-plains/finding/key-message-22-1 url: ~ - chapter_identifier: northern-great-plains confidence: "There is very high confidence that longer growing seasons have already benefited agriculture in parts of the Northern Great Plains. There is very high confidence that increases in temperatures and atmospheric CO2 will likely increase production potential for the agricultural sector in the short term (the next 10–20 years) and that current adaptations already being implemented by a subset of producers in this region provide opportunities for assessment, further development, and adoption by the larger population of agricultural managers. There is very high confidence that rising temperatures and changes in extreme weather events are very likely to have negative impacts on parts of the region. Over the longer-term (through the end of the 21st century), predicted climate changes may require transformative changes in agricultural management, including regional shifts of agricultural practices and enterprises (very likely, high confidence).{{< tbib '61' '18bc8646-9568-4169-a526-daed1216a4f0' >}},{{
Several lines of research have shown that agricultural productivity is likely to increase in rangelands across the region with increasing atmospheric carbon dioxide (CO2) and warming,{{< tbib '3' '26b61192-351a-494d-84f8-411c3e4ccd48' >}},{{
Numerous lines of research have addressed adaptation strategies for various parts of the agricultural sector{{< tbib '9' 'b1cbd298-7ce4-4106-a802-f8de95517c97' >}},{{
The chapter lead (CL) and coordinating lead author (CLA) developed a list of potential contributing authors by soliciting suggestions from the past National Climate Assessment (NCA) author team, colleagues and collaborators throughout the region, and contributors to other regional reports. Our initial list of potential authors also included CL nominees submitted to the U.S. Global Change Research Program (USGCRP). The CL and CLA discussed the Northern Great Plains, which was part of the larger Great Plains region for the Third National Climate Assessment (NCA3), with each of these nominees and, as part of that discussion, solicited suggestions for other nominees. This long list of potential contributing authors was pared down by omitting individuals who could not contribute in a timely fashion, and the list was finalized after reconciliation against key themes within the region identified by past NCA authors, the CL and CLA, and contributing author nominees. The team of contributing authors was selected to represent the region geographically and thematically, but participants from some states who had agreed to contribute were eventually unable to do so. Others were unable to contribute from the start. The author team is mostly composed of authors who did not contribute to NCA3.
The CL and CLA, in consultation with past NCA authors and contributing author nominees, identified an initial list of focal areas of regional importance. The author team then solicited input from colleagues and regional experts (identified based on their deep ties to scientific and practitioner communities across the region) on their thoughts on focal areas. This list informed the agenda of a region-wide meeting held on February 22, 2017, with core locations in Fort Collins, Colorado, and Rapid City, South Dakota. The main purpose of this meeting was to seek feedback on the proposed list of focal areas. With this feedback, the author team was able to refine our focal areas to the five themes comprising the Key Messages of the Northern Great Plains regional chapter. Of these, recreation/tourism is a focus area that is new from NCA3.
' report_identifier: nca4 statement: 'Agriculture is an integral component of the economy, the history, and the culture of the Northern Great Plains. Recently, agriculture has benefited from longer growing seasons and other recent climatic changes (very high confidence). Some additional production and conservation benefits are expected in the next two to three decades as land managers employ innovative adaptation strategies (very likely, high confidence), but rising temperatures and changes in extreme weather events are very likely to have negative impacts on parts of the region (very likely, very high confidence). Adaptation to extremes and to longer-term, persistent climate changes will likely require transformative changes in agricultural management, including regional shifts of agricultural practices and enterprises (very likely, high confidence).
' uncertainties: "While there is high confidence in future increases in temperature, uncertainties exist as to the changes in extreme events, including the spatiotemporal aspects of high-intensity rainfall events, snowstorms, and hailstorms. Perhaps most important are the uncertainties in the degree of precipitation variability from year to year{{< tbib '35' '8c567c0c-cc42-4372-94ea-7abf677704c6' >}} that influence decision-making calendars for agricultural producers.
" uri: /report/nca4/chapter/northern-great-plains/finding/key-message-22-2 url: ~ - chapter_identifier: northern-great-plains confidence: 'We know with very high confidence that ecosystems across the Northern Great Plains provide recreational opportunities and other valuable goods and services. We know with very high confidence that climate change is very likely affecting abiotic factors that influence these ecosystems, such as snowfall, spring snowmelt, runoff, and stream temperatures. There is high confidence that these abiotic factors are likely to affect high-elevation ecosystems and riparian areas in the Northern Great Plains. Greater confidence could be gained by conducting studies specifically within the Northern Great Plains, as opposed to drawing inferences from studies conducted in other regions of the world with similar characteristics. The consequences of ecosystem changes for local economies in the region that depend on winter-based or river-based recreational activities are currently being debated in the scientific literature, due to uncertainty about potential individual behavioral responses to changes in the recreational environment. Based on a limited number of case studies, effects of climate change on outdoor recreation-based economies are as likely as not to be negative, but this is only known with medium confidence. We know with very high confidence, however, that some natural ecosystems that local economies depend upon—in this specific case, wetlands in the Northern Great Plains—are likely to be negatively affected by climate-induced changes in agricultural land use. In turn, we know with high confidence that wetland declines will very likely harm the diverse species and recreational amenities they support. Uncertainty about future policies that could influence agricultural land-use decisions and wetland conservation outcomes precludes a higher confidence level or higher likelihood.
' evidence: "State-level surveys, conducted roughly every five years, have consistently documented that the public spends millions of days each year (over $30 million in 2011) participating in nature-based recreation activities in the Northern Great Plains (e.g., U.S. Department of the Interior and U.S. Department of Commerce 2008, 2013a, 2013b, 2014a, 2014b{{< tbib '65' 'ff8fa307-6c14-4764-83f9-9529b7bd688c' >}},{{
The chapter lead (CL) and coordinating lead author (CLA) developed a list of potential contributing authors by soliciting suggestions from the past National Climate Assessment (NCA) author team, colleagues and collaborators throughout the region, and contributors to other regional reports. Our initial list of potential authors also included CL nominees submitted to the U.S. Global Change Research Program (USGCRP). The CL and CLA discussed the Northern Great Plains, which was part of the larger Great Plains region for the Third National Climate Assessment (NCA3), with each of these nominees and, as part of that discussion, solicited suggestions for other nominees. This long list of potential contributing authors was pared down by omitting individuals who could not contribute in a timely fashion, and the list was finalized after reconciliation against key themes within the region identified by past NCA authors, the CL and CLA, and contributing author nominees. The team of contributing authors was selected to represent the region geographically and thematically, but participants from some states who had agreed to contribute were eventually unable to do so. Others were unable to contribute from the start. The author team is mostly composed of authors who did not contribute to NCA3.
The CL and CLA, in consultation with past NCA authors and contributing author nominees, identified an initial list of focal areas of regional importance. The author team then solicited input from colleagues and regional experts (identified based on their deep ties to scientific and practitioner communities across the region) on their thoughts on focal areas. This list informed the agenda of a region-wide meeting held on February 22, 2017, with core locations in Fort Collins, Colorado, and Rapid City, South Dakota. The main purpose of this meeting was to seek feedback on the proposed list of focal areas. With this feedback, the author team was able to refine our focal areas to the five themes comprising the Key Messages of the Northern Great Plains regional chapter. Of these, recreation/tourism is a focus area that is new from NCA3.
' report_identifier: nca4 statement: 'Ecosystems across the Northern Great Plains provide recreational opportunities and other valuable goods and services that are at risk in a changing climate (very high confidence). Rising temperatures have already resulted in shorter snow seasons, lower summer streamflows, and higher stream temperatures and have negatively affected high-elevation ecosystems and riparian areas, with important consequences for local economies that depend on winter or river-based recreational activities (high confidence). Climate-induced land-use changes in agriculture can have cascading effects on closely entwined natural ecosystems, such as wetlands, and the diverse species and recreational amenities they support (very high confidence, likely). Federal, tribal, state, and private organizations are undertaking preparedness and adaptation activities, such as scenario planning, transboundary collaboration, and development of market-based tools.
' uncertainties: 'Climate change is expected to disrupt local economies that depend on winter-based or river-based recreational activities. However, the magnitudes of these effects are uncertain. This is due largely to uncertainties about the preferences of recreationalists and the extent to which they will adapt by shifting the timing and location of their activities or by substituting towards a different set of recreational activities. For example, although climate change will make it more difficult to supply high-quality downhill skiing opportunities, this effect will be stronger in lower-elevation areas. Therefore, some skiers might adapt by simply traveling to higher-elevation downhill ski areas. Others might compensate for the shorter ski season at their favorite lower-elevation mountain by shifting some of their recreational time to an alternative outdoor activity, such as winter mountain biking. Given the potential diversity of individual preferences for adapting outdoor recreation activities to climate change, it is challenging to project with certainty the future potential impacts to recreation-dependent economies, but the impact will be larger and more immediate for some industries and companies (e.g., low-altitude ski resorts).
Another source of uncertainty is the reliance, in some cases, on scientific studies from other geographic locations to infer what the impacts of climate change might be for ecosystems, species, or recreationalists within the Northern Great Plains. For example, the effects of increased stream temperature on the susceptibility of coldwater fish species to diseases in the region are based largely on studies conducted in European coldwater fisheries.
Regarding wetlands in the Prairie Pothole Region, uncertainty about their abundance in the future arises from uncertainty about future government policies that would either exacerbate or mitigate climate-induced losses. For example, future versions of the Farm Bill may contain language that directly encourages wetland preservation (e.g., through conservation-compliance requirements) or unintentionally leads to wetland degradation (e.g., through higher subsidies for row crop insurance).
' uri: /report/nca4/chapter/northern-great-plains/finding/key-message-22-3 url: ~ - chapter_identifier: northern-great-plains confidence: 'There is high confidence that climate change and extreme weather events will likely put energy supply and infrastructure of various types at risk. There is high confidence that the energy sector is a very likely a significant source of greenhouse gases contributing to climate change. There is very high confidence that volatile organic compounds contribute to climate change and ground-level ozone pollution, and it is likely that this will worsen in the future in some areas.
' evidence: "Fossil fuel and renewable energy production/distribution infrastructure is expanding within the Northern Great Plains, including oil and natural gas pipelines, natural gas compressor stations and storage tanks, natural gas processing plants, natural gas-fired power plants, high-voltage power lines and substations, wind farms, and even a new oil refinery and a new biorefinery in recent years (both began operations in 2015).
A number of oil and natural gas pipelines are being constructed or have been completed in recent years. In particular, the Dakota Access Pipeline began commercial service June 1, 2017, transporting crude oil from the Bakken/Three Forks production areas in North Dakota, through South Dakota and Iowa, to Pakota, Illinois. While pipelines are vulnerable to damage or disruption from heavy precipitation events and associated flooding and erosion,{{< tbib '13' '07b7c06f-35f8-4205-a585-b45e3de00f22' >}} their increased use could eliminate hundreds of rail cars and trucks needed to transport crude every day. This reduces the exposure of these modes of transportation to rising temperatures, heat waves, and floods.{{< tbib '13' '07b7c06f-35f8-4205-a585-b45e3de00f22' >}} Other oil and gas production and distribution infrastructure is similarly vulnerable to heavy precipitation events and flooding.
The region relies on rail lines to transport coal, and these lines are vulnerable to rising temperatures, heat waves, and floods.{{< tbib '13' '07b7c06f-35f8-4205-a585-b45e3de00f22' >}} There is ample evidence of rail line vulnerability to extreme weather.{{< tbib '151' '96b39da1-771b-4889-8535-6b3ba61b7042' >}}
Damage to thermoelectric power plants and electric power transmission lines from extreme weather such as heat waves and wildfires has been documented, and the risk is expected to increase.{{< tbib '13' '07b7c06f-35f8-4205-a585-b45e3de00f22' >}},{{
The U.S. Department of Energy (DOE) Energy Risk Profiles (1996–2014) highlight the risks to energy infrastructure in the United States from natural hazards. For example, in North Dakota, thunderstorms and lightning had the highest frequency of occurrence and property loss during this timeframe. DOE also has a series of comprehensive documents on U.S. energy sector vulnerabilities to climate change{{< tbib '13' '07b7c06f-35f8-4205-a585-b45e3de00f22' >}},{{
There is substantial evidence that the energy sector is a significant source of greenhouse gases that contribute to climate change, in particular from power plants, oil and gas systems, and refineries.{{< tbib '117' '81430bfc-5d67-4109-982a-4cfd344f057c' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/northern-great-plains/finding/key-message-22-4.yaml identifier: key-message-22-4 ordinal: 4 process: 'The chapter lead (CL) and coordinating lead author (CLA) developed a list of potential contributing authors by soliciting suggestions from the past National Climate Assessment (NCA) author team, colleagues and collaborators throughout the region, and contributors to other regional reports. Our initial list of potential authors also included CL nominees submitted to the U.S. Global Change Research Program (USGCRP). The CL and CLA discussed the Northern Great Plains, which was part of the larger Great Plains region for the Third National Climate Assessment (NCA3), with each of these nominees and, as part of that discussion, solicited suggestions for other nominees. This long list of potential contributing authors was pared down by omitting individuals who could not contribute in a timely fashion, and the list was finalized after reconciliation against key themes within the region identified by past NCA authors, the CL and CLA, and contributing author nominees. The team of contributing authors was selected to represent the region geographically and thematically, but participants from some states who had agreed to contribute were eventually unable to do so. Others were unable to contribute from the start. The author team is mostly composed of authors who did not contribute to NCA3.
The CL and CLA, in consultation with past NCA authors and contributing author nominees, identified an initial list of focal areas of regional importance. The author team then solicited input from colleagues and regional experts (identified based on their deep ties to scientific and practitioner communities across the region) on their thoughts on focal areas. This list informed the agenda of a region-wide meeting held on February 22, 2017, with core locations in Fort Collins, Colorado, and Rapid City, South Dakota. The main purpose of this meeting was to seek feedback on the proposed list of focal areas. With this feedback, the author team was able to refine our focal areas to the five themes comprising the Key Messages of the Northern Great Plains regional chapter. Of these, recreation/tourism is a focus area that is new from NCA3.
' report_identifier: nca4 statement: 'Fossil fuel and renewable energy production and distribution infrastructure is expanding within the Northern Great Plains (very high confidence). Climate change and extreme weather events put this infrastructure at risk, as well as the supply of energy it contributes to support individuals, communities, and the U.S. economy as a whole (likely, high confidence). The energy sector is also a significant source of greenhouse gases (very likely, very high confidence) and volatile organic compounds that contribute to climate change and ground-level ozone pollution (likely in some areas, very high confidence).
' uncertainties: "Cold waves are projected to be less intense in the future, reducing the risk of disruptions from cold to energy infrastructure.{{< tbib '13' '07b7c06f-35f8-4205-a585-b45e3de00f22' >}}
There is not yet substantial agreement among sources as to how a changing climate will ultimately affect wind resources in the United States in general and in the Northern Great Plains in particular.{{< tbib '153' 'b66b1462-75b3-4a9b-ae8d-de2e190cf84b' >}}
Projected increases in precipitation in the Northern Great Plains are likely to benefit hydropower production, but this will vary by location. For example, it is known that in the Columbia River Basin, decreasing summer streamflows will reduce downstream hydropower production, and increasing winter and early spring streamflows will increase production.{{< tbib '13' '07b7c06f-35f8-4205-a585-b45e3de00f22' >}} In the Missouri River Basin, projected seasonal declines in precipitation in the southern and western portion of the region are likely to reduce the water available to generate hydropower.{{< tbib '13' '07b7c06f-35f8-4205-a585-b45e3de00f22' >}}
Biofuel feedstocks from crops and forage grown in the Northern Great Plains are vulnerable to climate change, but the net impacts on biofuel production are uncertain.{{< tbib '13' '07b7c06f-35f8-4205-a585-b45e3de00f22' >}}
It is well understood that ground-level ozone (O3) is created by chemical reactions between volatile organic compounds in the presence of sunlight and would be exacerbated by climate change. What is less understood is the sensitivity of regional climate-induced O3 changes, and the science of modeling climate and atmospheric chemistry to understand future conditions.
" uri: /report/nca4/chapter/northern-great-plains/finding/key-message-22-4 url: ~ - chapter_identifier: northern-great-plains confidence: 'There is very high confidence that rising temperature and increases in flooding, runoff events, and drought are likely to lead to increases in impacts to reservations and other Indigenous communities. There is very high confidence that climate changes are already resulting in harmful impacts on tribal economies, livelihoods, and culture. However, the actual impacts and response capacities will depend on the response of regulatory systems and funding amounts.
' evidence: "Multiple lines of research have shown that hydrological changes and changes in extremes have resulted in deleterious impacts to Indigenous peoples.{{< tbib '14' '5f9a3ea9-c2f0-44dc-916a-d3aab217c58d' >}},{{
The chapter lead (CL) and coordinating lead author (CLA) developed a list of potential contributing authors by soliciting suggestions from the past National Climate Assessment (NCA) author team, colleagues and collaborators throughout the region, and contributors to other regional reports. Our initial list of potential authors also included CL nominees submitted to the U.S. Global Change Research Program (USGCRP). The CL and CLA discussed the Northern Great Plains, which was part of the larger Great Plains region for the Third National Climate Assessment (NCA3), with each of these nominees and, as part of that discussion, solicited suggestions for other nominees. This long list of potential contributing authors was pared down by omitting individuals who could not contribute in a timely fashion, and the list was finalized after reconciliation against key themes within the region identified by past NCA authors, the CL and CLA, and contributing author nominees. The team of contributing authors was selected to represent the region geographically and thematically, but participants from some states who had agreed to contribute were eventually unable to do so. Others were unable to contribute from the start. The author team is mostly composed of authors who did not contribute to NCA3.
The CL and CLA, in consultation with past NCA authors and contributing author nominees, identified an initial list of focal areas of regional importance. The author team then solicited input from colleagues and regional experts (identified based on their deep ties to scientific and practitioner communities across the region) on their thoughts on focal areas. This list informed the agenda of a region-wide meeting held on February 22, 2017, with core locations in Fort Collins, Colorado, and Rapid City, South Dakota. The main purpose of this meeting was to seek feedback on the proposed list of focal areas. With this feedback, the author team was able to refine our focal areas to the five themes comprising the Key Messages of the Northern Great Plains regional chapter. Of these, recreation/tourism is a focus area that is new from NCA3.
' report_identifier: nca4 statement: 'Indigenous peoples of the Northern Great Plains are at high risk from a variety of climate change impacts, especially those resulting from hydrological changes, including changes in snowpack, seasonality and timing of precipitation events, and extreme flooding and droughts as well as melting glaciers and reduction in streamflows (likely, very high confidence). These changes are already resulting in harmful impacts to tribal economies, livelihoods, and sacred waters and plants used for ceremonies, medicine, and subsistence (very high confidence). At the same time, many tribes have been very proactive in adaptation and strategic climate change planning (very likely, very high confidence).
' uncertainties: 'The impacts of climate change in the Northern Great Plains are expected to increase risks to Indigenous reservations, communities, and livelihoods. However, there is uncertainty about how Indigenous people will be able to respond. Much of this uncertainty is due to unsettled water rights, multijurisdictional complexities, and federal funding and policies.
' uri: /report/nca4/chapter/northern-great-plains/finding/key-message-22-5 url: ~ - chapter_identifier: southern-great-plains confidence: "The Southern Great Plains will continue to grow rapidly and with high probability of significant competition. Water is the major concern, and political inability to develop a system to allocate water in an equitable manner will continue to build this competitive and contentious issue among all users—energy, food, and water. Quality of life in the region will be compromised as population increases. At least 60% of the region’s population is clustered around urban centers currently, but these population centers are experiencing growth that far exceeds that of rural communities. The remaining population is distributed across vast areas of rural land.{{< tbib '14' 'bf19cfe7-2575-48e2-8d26-b0081117369a' >}},{{
A growing number of adaptation strategies, improved climate services, and early warning decision support systems will more effectively manage the complex regional, national, and transnational issues associated with food, energy, and water. Since a changing climate has significant negative impacts on agriculture in the United States and causes substantial economic costs,{{< tbib '38' '76db17ce-354b-4f0c-ad10-3e701c0387fc' >}} the effects of drought and other occurrences of extreme weather outside the region will also affect the food–energy–water interconnections within the region. (Likely, High confidence)
" evidence: "The connection between food, water, and energy also creates great challenges in the management and distribution of resources. People need food, energy, and water, yet all sectors pull from each other and allocation is a challenge. There are many studies focused on the competitive nature revolving around these resources and the demand by people.{{< tbib '41' '10b9c70e-cabf-44c8-87e7-7905e1fa1e67' >}},{{
The initial Southern Great Plains author team was selected such that expertise from each of the states’ officially recognized climate offices in the region (Kansas, Oklahoma, and Texas) were included. The offices of the state climatologist in Kansas, Oklahoma, and Texas are each members of the American Association of State Climatologists, which is the recognized professional scientific organization for climate expertise at the state level.
One representative from each of several regional hubs of national and regional climate expertise was included on the author team. These regional hubs include the U.S. Department of Agriculture’s Southern Plains Climate Hub (El Reno, Oklahoma), the U.S. Department of the Interior’s South Central Climate Adaptation Science Center (Norman, Oklahoma), and the National Oceanic and Atmospheric Administration’s Regional Integrated Sciences and Assessments Southern Climate Impacts Planning Program (Norman, Oklahoma).
After assessing the areas of expertise of the six authors selected from the state and regional centers, a gap analysis was conducted to prioritize areas of expertise that were missing. Due to the importance of the sovereign tribal nations to the Southern Great Plains, an accomplished scholar with expertise in Indigenous knowledge on the environment and climate change was selected from the premier tribal university in the United States, Haskell Indian Nations University in Lawrence, Kansas. An individual from the Environmental Science Institute at the University of Texas at Austin was selected to bring expertise on the complex intersection of coupled atmosphere–land–ocean systems, climate, and humans (population and urbanization). Expertise in the electric utility industry was gained through the Oklahoma Association of Electric Cooperatives by an individual with a long history of working with rural and urban populations and with researchers and forecasters in weather and climate.
The author group decided to allow Southern Great Plains stakeholders to drive additional priorities. On March 2, 2017, the Fourth National Climate Assessment (NCA4) Southern Great Plains chapter team held a Regional Engagement Workshop at the National Weather Center in Norman, Oklahoma, with a satellite location in Austin, Texas, that allowed a number of stakeholders to participate virtually. The objective of the workshop was to gather input from a diverse array of stakeholders throughout the Southern Great Plains to help inform the writing and development of the report and to raise awareness of the process and timeline for NCA4. Stakeholders from meteorology, climatology, tribes, agriculture, electric utilities, water resources, Bureau of Land Management, ecosystems, landscape cooperatives, and transportation from Kansas, Oklahoma, and Texas were represented. The productive dialog at this workshop identified important gaps in environmental economics, ecosystems, and health. Scientists working at the cutting edge of research in these three areas were selected: an ecosystems expert from the Texas Parks and Wildlife Department, an environmental economist from the department of Geography and Environmental Sustainability at the University of Oklahoma, and health experts from the University of Colorado School of Medicine and the Aspen Global Change Institute.
This diverse collection of medical doctors, academics, researchers, scientists, and practitioners from both federal and state agencies gives the Southern Great Plains chapter a wealth of expertise across the many ways in which climate change will affect people in the region.
' report_identifier: nca4 statement: 'Quality of life in the region will be compromised as increasing population, the migration of individuals from rural to urban locations, and a changing climate redistribute demand at the intersection of food consumption, energy production, and water resources (likely, high confidence). A growing number of adaptation strategies, improved climate services, and early warning decision support systems will more effectively manage the complex regional, national, and transnational issues associated with food, energy, and water (likely, high confidence).
' uncertainties: "Research into the intersection of food, energy, and water is in its early stages and historically tends to examine only one or two components.{{< tbib '59' '8a4477fb-8bb9-4b37-8c31-3307f22d84c4' >}},{{
There is very high confidence that extreme heat will increase in frequency and intensity. There is medium confidence in an increased frequency of flooding and high confidence in the increased frequency of drought. There is high confidence of sea level rise of at least 4 feet by 2100 along the Texas coastline if greenhouse gas emissions are not reduced. On the implications for infrastructure, there is high confidence that weather-related damage will increase due to inland weather-related hazards. Along the coastline, there is very high confidence that infrastructure will be impacted by sea level rise and storm surge.
' evidence: "The existing infrastructure and projected models for growth are well established and documented. Demographic and population projections are available from state demographers and are typically included in Long-Term Transportation Plans available from state departments of transportation. Additionally, the present-day infrastructure challenges have been examined in depth by the American Society for Civil Engineers (ASCE), which publishes an Infrastructure Report Card for the Nation and for each state (www.infrastructurereportcard.org).{{< tbib '189' '497411ba-3eb8-42fd-9b01-8c5a21fc6465' >}} For the Southern Great Plains states, one of the pressing concerns is meeting the funding challenges necessary to maintain critical infrastructure, as well as anticipating future revenue streams, which themselves depend on population and its distribution, and state and federal funding. The ASCE, as well as all state transportation plans in the Southern Great Plains, does not consider future climate projections, and the information contained generally does not explicitly mention climate-related stressors. However, the impacts of climate change have become an issue of concern for agencies such as the Department of Transportation (DOT) and Federal Highways Administration (FHWA), which have in recent years funded projects evaluating the potential impacts of climate change on infrastructure and transportation and possible adaptation strategies. Since 2010, the FHWA has sponsored a series of pilot studies in resilience for municipalities and states across the Nation.{{< tbib '190' '93ad29e2-8811-4b6e-854c-fa57408cb570' >}} Two of these studies took place in Texas, in Dallas and Tarrant Counties and in the City of Austin. These reports provide some of the most comprehensive examples of integrating climate data into assessments of infrastructure vulnerability in the region to date. The potential impacts of temperature and precipitation extremes on transportation and infrastructure were based in part on known vulnerabilities as shown by these aforementioned reports and the larger repository of information and resources supplied by the FHWA.
Estimates of relative sea level rise (SLR) in Texas in the historical period are available from NCA4 Volume I: Climate Science Special Report,{{< tbib '24' '75cf1c0b-cc62-4ca4-96a7-082afdfe2ab1' >}} Runkle et al. (2017),{{< tbib '25' '58dfbe91-53a4-4ddb-ad8d-d4e181086e72' >}} Sweet et al. (2017).{{< tbib '191' 'c66bf5a9-a6d7-4043-ad99-db0ae6ae562c' >}} Relative SLR along the Texas coastline is some of the highest in the Nation; coupled with its population and critical energy infrastructure, this region has some noteworthy vulnerabilities to SLR. Projections of SLR remain uncertain and depend to some extent on whether the current rates of relative SLR are maintained, in addition to the magnitude and rate of greenhouse gas emissions. Sweet et al. (2017){{< tbib '191' 'c66bf5a9-a6d7-4043-ad99-db0ae6ae562c' >}} probabilistically evaluate a number of SLR scenarios, typically noting that the Texas coast SLR is higher than the global mean. The values mentioned in the main text are global mean values obtained from USGCRP (2017){{< tbib '24' '75cf1c0b-cc62-4ca4-96a7-082afdfe2ab1' >}} and from the range quoted by Runkle et al. (2017).{{< tbib '25' '58dfbe91-53a4-4ddb-ad8d-d4e181086e72' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/southern-great-plains/finding/key-message-23-2.yaml identifier: key-message-23-2 ordinal: 2 process: 'The initial Southern Great Plains author team was selected such that expertise from each of the states’ officially recognized climate offices in the region (Kansas, Oklahoma, and Texas) were included. The offices of the state climatologist in Kansas, Oklahoma, and Texas are each members of the American Association of State Climatologists, which is the recognized professional scientific organization for climate expertise at the state level.
One representative from each of several regional hubs of national and regional climate expertise was included on the author team. These regional hubs include the U.S. Department of Agriculture’s Southern Plains Climate Hub (El Reno, Oklahoma), the U.S. Department of the Interior’s South Central Climate Adaptation Science Center (Norman, Oklahoma), and the National Oceanic and Atmospheric Administration’s Regional Integrated Sciences and Assessments Southern Climate Impacts Planning Program (Norman, Oklahoma).
After assessing the areas of expertise of the six authors selected from the state and regional centers, a gap analysis was conducted to prioritize areas of expertise that were missing. Due to the importance of the sovereign tribal nations to the Southern Great Plains, an accomplished scholar with expertise in Indigenous knowledge on the environment and climate change was selected from the premier tribal university in the United States, Haskell Indian Nations University in Lawrence, Kansas. An individual from the Environmental Science Institute at the University of Texas at Austin was selected to bring expertise on the complex intersection of coupled atmosphere–land–ocean systems, climate, and humans (population and urbanization). Expertise in the electric utility industry was gained through the Oklahoma Association of Electric Cooperatives by an individual with a long history of working with rural and urban populations and with researchers and forecasters in weather and climate.
The author group decided to allow Southern Great Plains stakeholders to drive additional priorities. On March 2, 2017, the Fourth National Climate Assessment (NCA4) Southern Great Plains chapter team held a Regional Engagement Workshop at the National Weather Center in Norman, Oklahoma, with a satellite location in Austin, Texas, that allowed a number of stakeholders to participate virtually. The objective of the workshop was to gather input from a diverse array of stakeholders throughout the Southern Great Plains to help inform the writing and development of the report and to raise awareness of the process and timeline for NCA4. Stakeholders from meteorology, climatology, tribes, agriculture, electric utilities, water resources, Bureau of Land Management, ecosystems, landscape cooperatives, and transportation from Kansas, Oklahoma, and Texas were represented. The productive dialog at this workshop identified important gaps in environmental economics, ecosystems, and health. Scientists working at the cutting edge of research in these three areas were selected: an ecosystems expert from the Texas Parks and Wildlife Department, an environmental economist from the department of Geography and Environmental Sustainability at the University of Oklahoma, and health experts from the University of Colorado School of Medicine and the Aspen Global Change Institute.
This diverse collection of medical doctors, academics, researchers, scientists, and practitioners from both federal and state agencies gives the Southern Great Plains chapter a wealth of expertise across the many ways in which climate change will affect people in the region.
' report_identifier: nca4 statement: 'The built environment is vulnerable to increasing temperature, extreme precipitation, and continued sea level rise, particularly as infrastructure ages and populations shift to urban centers (likely, high confidence). Along the Texas Gulf Coast, relative sea level rise of twice the global average will put coastal infrastructure at risk (likely, medium confidence). Regional adaptation efforts that harden or relocate critical infrastructure will reduce the risk of climate change impacts.
' uncertainties: "In the Southern Great Plains there remains uncertainty over the direction of change of average precipitation, although models generally project increases in very heavy precipitation.{{< tbib '1' 'e8089a19-413e-4bc5-8c4a-7610399e268c' >}} The expectation of an increase in the frequency of events such as the 100-year storm is uncertain due to the spread of model projections of extreme precipitation and the need to use additional statistical modeling in order to obtain the return period estimates.
There are limited studies that attempt to directly link weather and climate extremes and their impacts to infrastructure. While it is appreciated that infrastructure exposed to adverse conditions will lead to deterioration, studies on specific cause–effect chain of events in these cases are limited (e.g., Winguth et al. 2015){{< tbib '192' '3fed1df6-1ec6-4f8b-a3b7-6bb715cee3ee' >}}. The results are more evident in the case of catastrophic failures associated with floods, for example, but even in those cases, antecedent conditions related to the age, condition, and/or construction quality of infrastructure will affect its resilience (Ch. 12: Transportation;).
" uri: /report/nca4/chapter/southern-great-plains/finding/key-message-23-2 url: ~ - chapter_identifier: southern-great-plains confidence: 'There is high confidence that rising temperatures and increases in flooding, runoff events, and aridity will likely lead to changes in the aquatic and terrestrial habitats supporting many regional species. Flooding has changed the complexity of many riparian habitats. Increases already seen in extreme drought occurrence have caused downturns in the fish- and wildlife-related industries, with losses in traditional fish (crab and oysters) and wildlife species (waterfowl) important for both recreational and commercial purposes.
In contrast, habitat created by invasive species due to climate change has improved populations of other species including fungi. The expanded stress due to a rapidly growing population in this region increases the likelihood (high confidence) of negative natural resource and ecosystems outcomes in the future.
' evidence: "This Key Message was developed through technical discussions developed within science teams and collaborators of the Gulf Coast and Great Plains Landscape Conservation Cooperatives. Species’ response to climate change is complex and variable;{{< tbib '119' '506759aa-765f-4007-a678-17d69d139e39' >}} this complexity necessitates a multifaceted review of the projected impacts of climate change. In addition, ecosystem services also require assessment, given the impact of climate change on their ability to deliver materials and processes that benefit people.{{< tbib '123' 'c3b02b08-e555-4a41-8a73-8b04dc89ee6b' >}}
The following relevant areas of evidence regarding climate change impacts on ecosystems in the Southern Great Plains were therefore considered: species, aquatic ecosystems, coastal bays and estuaries, and risk management. It is unclear how climate change will affect species directly, but the effects of increased aridity will likely have negative impacts (e.g., NFWPCAP 2012{{< tbib '123' 'c3b02b08-e555-4a41-8a73-8b04dc89ee6b' >}}). Species migration (e.g., Schmandt 2011{{< tbib '126' '373310ba-0499-4640-8a23-211736f3b32d' >}}) and mortality (e.g., Moore et al 2016{{< tbib '127' 'f1380bfc-e39d-43d9-87d6-dfcff35fa7fb' >}}) will increase in response to climate change. Climate change impacts to aquatic ecosystems include higher water temperatures in lakes, wetlands, rivers, and estuaries, while impacts to reservoirs include fluctuating lake levels, loss of habitat, loss of recreational access, increase in harmful algal blooms, and disconnectedness from upstream and downstream riverine habitat.{{< tbib '129' '9bff2ebb-6418-481a-bad9-b8c29875286e' >}} Sea level rise will impact coastal bays and estuaries via more frequent and longer-lasting flooding of marshes,{{< tbib '126' '373310ba-0499-4640-8a23-211736f3b32d' >}},{{
The initial Southern Great Plains author team was selected such that expertise from each of the states’ officially recognized climate offices in the region (Kansas, Oklahoma, and Texas) were included. The offices of the state climatologist in Kansas, Oklahoma, and Texas are each members of the American Association of State Climatologists, which is the recognized professional scientific organization for climate expertise at the state level.
One representative from each of several regional hubs of national and regional climate expertise was included on the author team. These regional hubs include the U.S. Department of Agriculture’s Southern Plains Climate Hub (El Reno, Oklahoma), the U.S. Department of the Interior’s South Central Climate Adaptation Science Center (Norman, Oklahoma), and the National Oceanic and Atmospheric Administration’s Regional Integrated Sciences and Assessments Southern Climate Impacts Planning Program (Norman, Oklahoma).
After assessing the areas of expertise of the six authors selected from the state and regional centers, a gap analysis was conducted to prioritize areas of expertise that were missing. Due to the importance of the sovereign tribal nations to the Southern Great Plains, an accomplished scholar with expertise in Indigenous knowledge on the environment and climate change was selected from the premier tribal university in the United States, Haskell Indian Nations University in Lawrence, Kansas. An individual from the Environmental Science Institute at the University of Texas at Austin was selected to bring expertise on the complex intersection of coupled atmosphere–land–ocean systems, climate, and humans (population and urbanization). Expertise in the electric utility industry was gained through the Oklahoma Association of Electric Cooperatives by an individual with a long history of working with rural and urban populations and with researchers and forecasters in weather and climate.
The author group decided to allow Southern Great Plains stakeholders to drive additional priorities. On March 2, 2017, the Fourth National Climate Assessment (NCA4) Southern Great Plains chapter team held a Regional Engagement Workshop at the National Weather Center in Norman, Oklahoma, with a satellite location in Austin, Texas, that allowed a number of stakeholders to participate virtually. The objective of the workshop was to gather input from a diverse array of stakeholders throughout the Southern Great Plains to help inform the writing and development of the report and to raise awareness of the process and timeline for NCA4. Stakeholders from meteorology, climatology, tribes, agriculture, electric utilities, water resources, Bureau of Land Management, ecosystems, landscape cooperatives, and transportation from Kansas, Oklahoma, and Texas were represented. The productive dialog at this workshop identified important gaps in environmental economics, ecosystems, and health. Scientists working at the cutting edge of research in these three areas were selected: an ecosystems expert from the Texas Parks and Wildlife Department, an environmental economist from the department of Geography and Environmental Sustainability at the University of Oklahoma, and health experts from the University of Colorado School of Medicine and the Aspen Global Change Institute.
This diverse collection of medical doctors, academics, researchers, scientists, and practitioners from both federal and state agencies gives the Southern Great Plains chapter a wealth of expertise across the many ways in which climate change will affect people in the region.
' report_identifier: nca4 statement: 'Terrestrial and aquatic ecosystems are being directly and indirectly altered by climate change (likely, high confidence). Some species can adapt to extreme droughts, unprecedented floods, and wildfires from a changing climate, while others cannot, resulting in significant impacts to both services and people living in these ecosystems (likely, high confidence). Landscape-scale ecological services will increase the resilience of the most vulnerable species.
' uncertainties: "Ecosystems and the species that exist in these ecosystems have experienced a rapid decline in many “common species” as well as certain rare species.{{< tbib '123' 'c3b02b08-e555-4a41-8a73-8b04dc89ee6b' >}},{{
There is very high confidence that rising temperatures and changes in precipitation leading to flooding, runoff events, and aridity will likely lead to negative impacts on human health in the Southern Great Plains. There is high confidence that certain populations, such as very young and old and socioeconomically disadvantaged individuals, will likely be disproportionately affected.
' evidence: "This Key Message was developed in close coordination with the Human Health (Ch. 14) author team and incorporated applicable inputs from the U.S. Climate and Health Assessment.{{< tbib '168' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} Multiple lines of evidence demonstrate statistically significant associations between temperature, precipitation, and other climatologic variables with adverse health outcomes, including heat-related illness, respiratory disease, malnutrition, and vector-borne disease.{{< tbib '168' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} Regionally specific examples of these well-documented impacts were identified through literature reviews conducted to identify regionally specific studies of these impacts.
There is strong evidence that increasing average temperatures as well as increasing frequency, duration, and intensity of extreme heat events will occur in the Southern Great Plains by the middle and end of this century, with higher CO2 emissions leading to greater and faster temperature increases.{{< tbib '80' '29960c69-6168-4fb0-9af0-d50bdd91acd3' >}} Extreme temperatures are shown with high confidence to have substantial effects on morbidity and mortality {{< tbib '142' 'e337db11-d5e9-4a9b-be9f-7773befd61b9' >}},{{
Climate change is expected (with medium to high confidence) to increase the frequency of extreme rainfall and hurricanes, although impacts in the Southern Great Plains remain difficult to quantify.{{< tbib '2' '52ce1b63-1b04-4728-9f1b-daee39af665e' >}} The Gulf Coast of Texas in particular has experienced several record-breaking floods and tropical cyclones in recent years, including Hurricane Harvey. Hurricanes and resultant flooding result in significant health impacts, including deaths from drowning and trauma, critical shortages of essential medications, critical healthcare system power shortages, and forced patient evacuations.{{< tbib '9' 'b5bf5f25-1fd9-43bd-8493-0ef2ee771f47' >}} Such events strain healthcare resources not only within regions of direct hurricane impact but also within the entire region due to displacement of patient populations.{{< tbib '8' 'f8225523-7ae9-4ab4-ac28-4cfafe1b508b' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/southern-great-plains/finding/key-message-23-4.yaml identifier: key-message-23-4 ordinal: 4 process: 'The initial Southern Great Plains author team was selected such that expertise from each of the states’ officially recognized climate offices in the region (Kansas, Oklahoma, and Texas) were included. The offices of the state climatologist in Kansas, Oklahoma, and Texas are each members of the American Association of State Climatologists, which is the recognized professional scientific organization for climate expertise at the state level.
One representative from each of several regional hubs of national and regional climate expertise was included on the author team. These regional hubs include the U.S. Department of Agriculture’s Southern Plains Climate Hub (El Reno, Oklahoma), the U.S. Department of the Interior’s South Central Climate Adaptation Science Center (Norman, Oklahoma), and the National Oceanic and Atmospheric Administration’s Regional Integrated Sciences and Assessments Southern Climate Impacts Planning Program (Norman, Oklahoma).
After assessing the areas of expertise of the six authors selected from the state and regional centers, a gap analysis was conducted to prioritize areas of expertise that were missing. Due to the importance of the sovereign tribal nations to the Southern Great Plains, an accomplished scholar with expertise in Indigenous knowledge on the environment and climate change was selected from the premier tribal university in the United States, Haskell Indian Nations University in Lawrence, Kansas. An individual from the Environmental Science Institute at the University of Texas at Austin was selected to bring expertise on the complex intersection of coupled atmosphere–land–ocean systems, climate, and humans (population and urbanization). Expertise in the electric utility industry was gained through the Oklahoma Association of Electric Cooperatives by an individual with a long history of working with rural and urban populations and with researchers and forecasters in weather and climate.
The author group decided to allow Southern Great Plains stakeholders to drive additional priorities. On March 2, 2017, the Fourth National Climate Assessment (NCA4) Southern Great Plains chapter team held a Regional Engagement Workshop at the National Weather Center in Norman, Oklahoma, with a satellite location in Austin, Texas, that allowed a number of stakeholders to participate virtually. The objective of the workshop was to gather input from a diverse array of stakeholders throughout the Southern Great Plains to help inform the writing and development of the report and to raise awareness of the process and timeline for NCA4. Stakeholders from meteorology, climatology, tribes, agriculture, electric utilities, water resources, Bureau of Land Management, ecosystems, landscape cooperatives, and transportation from Kansas, Oklahoma, and Texas were represented. The productive dialog at this workshop identified important gaps in environmental economics, ecosystems, and health. Scientists working at the cutting edge of research in these three areas were selected: an ecosystems expert from the Texas Parks and Wildlife Department, an environmental economist from the department of Geography and Environmental Sustainability at the University of Oklahoma, and health experts from the University of Colorado School of Medicine and the Aspen Global Change Institute.
This diverse collection of medical doctors, academics, researchers, scientists, and practitioners from both federal and state agencies gives the Southern Great Plains chapter a wealth of expertise across the many ways in which climate change will affect people in the region.
' report_identifier: nca4 statement: 'Health threats, including heat illness and diseases transmitted through food, water, and insects, will increase as temperature rises (very likely, high confidence). Weather conditions supporting these health threats are projected to be of longer duration or occur at times of the year when these threats are not normally experienced (likely, medium confidence). Extreme weather events with resultant physical injury and population displacement are also a threat (likely, high confidence). These threats are likely to increase in frequency and distribution and are likely to create significant economic burdens (likely, high confidence). Vulnerability and adaptation assessments, comprehensive response plans, seasonal health forecasts, and early warning systems can be useful adaptation strategies.
' uncertainties: 'The ability to quantitatively predict specific health outcomes associated with projected changes in climate is limited by long-term public health data as well as meteorological data. While assessments consistently indicate that climate change will have direct and indirect impacts on human health (high confidence), quantifying specific health metrics, such as incidence and community level prevalence, remains difficult. The uncertainty develops when there are many connected actions that influence health outcomes. For example, the future impact of climate change on human health is likely to be reduced by adaptation measures that take place on local and national scales. Additionally, the role of non-climate factors, including land use, socioeconomics, and population characteristics (such as immigration), as well as health sector policies and practices, will affect local and regional health impacts. The magnitude of impact of these variables on health at local and regional scales is difficult to predict. The estimation of future economic impacts is limited by difficulties in estimating the true cost of healthcare delivery and additionally only partially captures the actual impacts on health and livelihood of individuals and communities. Thus, existing projections likely underestimate the entirety of the economic impact.
' uri: /report/nca4/chapter/southern-great-plains/finding/key-message-23-4 url: ~ - chapter_identifier: southern-great-plains confidence: 'There is high confidence that extreme events and long-term climate shifts will lead to changes in tribal and Indigenous communities in the Southern Great Plains. Environmental connections will be direct, but the degree of those connections is uncertain and shifts in climate system will impact each nation differently. How changes will be perceived and managed and what steps are taken to adapt are uncertain; thus, there is low confidence that adaptation will be a successful mechanism among all tribal and Indigenous peoples.
' evidence: "This Key Message was developed through dialog and discussions among Indigenous communities and within the social sciences discipline. While Indigenous communities vary in size from smaller nations to large well-formed governments, all are in need of communication about the realities of climate change.{{< tbib '14' 'bf19cfe7-2575-48e2-8d26-b0081117369a' >}} Climate change threatens the ability of tribes and Indigenous peoples to procure food, water, and shelter and to preserve ancient cultural activities.{{< tbib '179' '64063229-e3bd-4ab7-ba73-41909ca78211' >}},{{
The initial Southern Great Plains author team was selected such that expertise from each of the states’ officially recognized climate offices in the region (Kansas, Oklahoma, and Texas) were included. The offices of the state climatologist in Kansas, Oklahoma, and Texas are each members of the American Association of State Climatologists, which is the recognized professional scientific organization for climate expertise at the state level.
One representative from each of several regional hubs of national and regional climate expertise was included on the author team. These regional hubs include the U.S. Department of Agriculture’s Southern Plains Climate Hub (El Reno, Oklahoma), the U.S. Department of the Interior’s South Central Climate Adaptation Science Center (Norman, Oklahoma), and the National Oceanic and Atmospheric Administration’s Regional Integrated Sciences and Assessments Southern Climate Impacts Planning Program (Norman, Oklahoma).
After assessing the areas of expertise of the six authors selected from the state and regional centers, a gap analysis was conducted to prioritize areas of expertise that were missing. Due to the importance of the sovereign tribal nations to the Southern Great Plains, an accomplished scholar with expertise in Indigenous knowledge on the environment and climate change was selected from the premier tribal university in the United States, Haskell Indian Nations University in Lawrence, Kansas. An individual from the Environmental Science Institute at the University of Texas at Austin was selected to bring expertise on the complex intersection of coupled atmosphere–land–ocean systems, climate, and humans (population and urbanization). Expertise in the electric utility industry was gained through the Oklahoma Association of Electric Cooperatives by an individual with a long history of working with rural and urban populations and with researchers and forecasters in weather and climate.
The author group decided to allow Southern Great Plains stakeholders to drive additional priorities. On March 2, 2017, the Fourth National Climate Assessment (NCA4) Southern Great Plains chapter team held a Regional Engagement Workshop at the National Weather Center in Norman, Oklahoma, with a satellite location in Austin, Texas, that allowed a number of stakeholders to participate virtually. The objective of the workshop was to gather input from a diverse array of stakeholders throughout the Southern Great Plains to help inform the writing and development of the report and to raise awareness of the process and timeline for NCA4. Stakeholders from meteorology, climatology, tribes, agriculture, electric utilities, water resources, Bureau of Land Management, ecosystems, landscape cooperatives, and transportation from Kansas, Oklahoma, and Texas were represented. The productive dialog at this workshop identified important gaps in environmental economics, ecosystems, and health. Scientists working at the cutting edge of research in these three areas were selected: an ecosystems expert from the Texas Parks and Wildlife Department, an environmental economist from the department of Geography and Environmental Sustainability at the University of Oklahoma, and health experts from the University of Colorado School of Medicine and the Aspen Global Change Institute.
This diverse collection of medical doctors, academics, researchers, scientists, and practitioners from both federal and state agencies gives the Southern Great Plains chapter a wealth of expertise across the many ways in which climate change will affect people in the region.
' report_identifier: nca4 statement: 'Tribal and Indigenous communities are particularly vulnerable to climate change due to water resource constraints, extreme weather events, higher temperature, and other likely public health issues (likely, high confidence). Efforts to build community resilience can be hindered by economic, political, and infrastructure limitations (likely, high confidence), but traditional knowledge and intertribal organizations provide opportunities to adapt to the potential challenges of climate change.
' uncertainties: "There is a great deal of uncertainty regarding how tribal communities will integrate climate change into their cultures, given the variable size of these communities and the challenges of connecting and communicating with clarity among them. It is likely that adaptation strategies will vary greatly as knowledge and communication might not be widely supported within all nations.{{< tbib '169' '60233f20-d45f-4086-ada7-00dbd47712c3' >}},{{
There is high confidence that climate change, through reductions in snowpack, increased temperatures, and more variable precipitation, is already affecting the Northwest’s diverse natural resource base. There is high confidence that these natural resource sectors provide critical economic benefits, particularly for rural, tribal, and Indigenous communities who are more dependent on economic activities associated with natural resource management. There is high confidence that climate change will have a large impact on the natural resource sector throughout this century; however, there is medium confidence that these impacts will negatively impact rural, tribal, and Indigenous livelihoods, particularly about how projected changes will economically impact specific natural resource sectors due to large uncertainties surrounding global market dynamics that are influenced by climatic and non-climatic factors. It is very likely that proactive management efforts will be required to reduce climate risks, yet there is medium confidence that these adaptation efforts will adequately reduce negative impacts and promote sector-specific economic benefits.
' evidence: "Multiple studies suggest that Northwest natural resource sectors will likely be directly affected by climate change, including increased temperatures, changes in precipitation patterns, and reduced snowpack (see NOAA State Climate Summaries for Oregon, Washington, and Idaho).{{< tbib '265' 'ba49da5a-489b-420e-b593-8d83e4fbf5a5' >}},{{
There is good evidence that natural resource managers are attempting to build more resilient production systems in the face of climate change through the adoption of adaptation practices (see Box 24.1), particularly those that build soil resources to increase resilience in the face of more extreme and variable weather; however, in some cases not all adaptation strategies will necessarily lead to broader soil benefits.{{< tbib '270' '2a6fd72f-138b-46d2-9f9e-26277d961c13' >}},{{
Yet, how individual actors respond to changes in climate is a source of uncertainty, particularly if these actions do not reduce climate risks or capitalize on potential benefits as expected.{{< tbib '64' 'daa849df-9a29-44ee-b59c-9b4b5fd53467' >}} Additionally, many adaptive actions, at least in the short term, will likely be costly for individual producers to implement.{{< tbib '37' '28a86b7f-c68a-4d17-bd11-083814d9ed27' >}},{{
This assessment focuses on different aspects of the interaction between humans, the natural environment, and climate change, including reliance on natural resources for livelihoods, the less tangible values of nature, the built environment, health, and frontline communities. Therefore, the author team required a depth and breadth of expertise that went beyond climate change science and included social science, economics, health, tribes and Indigenous people, frontline communities, and climate adaptation, as well as expertise in agriculture, forestry, hydrology, coastal and ocean dynamics, and ecology. Prospective authors were nominated by their respective agencies, universities, organizations, or peers. All prospective authors were interviewed with respect to the qualifications, and selected authors committed to remain part of the team for the duration of chapter development.
The chapter was developed through technical discussions of relevant evidence and expert deliberation by the report authors at workshops, weekly teleconferences, and email exchanges. The author team, along with the U.S. Global Change Research Program (USGCRP), also held stakeholder meetings in Portland and Boise to solicit input and receive feedback on the outline and draft content under consideration. A series of breakout groups during the stakeholder meetings provided invaluable feedback that is directly reflected in how the Key Messages were shaped with respect to Northwest values and the intersection between humans, the natural environment, and climate change. The authors also considered inputs and comments submitted by the public, interested stakeholders, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. For additional information on the overall report process, see Appendix 1: Process. The author team also engaged in targeted consultations during multiple exchanges with contributing authors for other chapters, who provided additional expertise on subsets of the Traceable Accounts associated with each Key Message.
The climate change projections and scenarios used in this assessment have been widely examined and presented elsewhere{{< tbib '11' '07aed96a-e0e8-47dd-81d3-cdff5a6e261c' >}},{{
Climate change is already affecting the Northwest’s diverse natural resources (high confidence), which support sustainable livelihoods; provide a robust foundation for rural, tribal, and Indigenous communities; and strengthen local economies (high confidence). Climate change is expected to continue affecting the natural resource sector (likely, high confidence), but the economic consequences will depend on future market dynamics, management actions, and adaptation efforts (very likely, medium confidence). Proactive management can increase the resilience of many natural resources and their associated economies (very likely, medium confidence).
' uncertainties: "Climate impacts, such as increased temperatures, reduced snowpack, and more variable precipitation and subsequent impacts on pests, disease, fire incidence, and other secondary impacts will very likely indirectly affect livelihoods and the economic viability of natural resource sectors, with more severe impacts to rural, tribal, and Indigenous communities (Ch. 10: Ag & Rural). There is, however, greater uncertainty as to how precisely these impacts are projected to affect natural resource managers’ financial security and their subsequent land-use decisions (Ch. 5: Land Changes), as well as other factors important to sustainable livelihoods and community well-being.
This is particularly relevant for key commodities that are integrated with national and international markets that are influenced by multiple factors and are difficult to predict (Ch. 10: Ag & Rural; Ch. 16: International). National and global market dynamics will likely be influenced by broader climate change effects on other natural resource sectors in the United States and across the globe,{{< tbib '50' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}} while also being impacted by a broad array of factors that include technological developments, laws, regulations and policies affecting trade and subsidies, and security issues. There are instances where the economic consequences will likely be positive, particularly in comparison to other regions in the United States, such as found in the dairy production sector.{{< tbib '65' '4c87b5a3-0303-4f92-ae7b-97d5e20b9579' >}} The economic impacts to regional fisheries are much less certain as iconic species and industries in the Northwest struggle to maintain viability.{{< tbib '51' 'bfd896fb-e6cf-45bb-90fc-46742079789c' >}},{{
There is high confidence that climate change and extreme events have already endangered the well-being of a wide range of wildlife, fish, and plants. There is very high confidence that these impacts will directly threaten tribal subsistence and culture and high confidence that these impacts will threaten popular recreation activities. Future climate change will very likely continue to have adverse impacts on the regional environment. There is high confidence that future climate change will have negative impacts on the values, identity, heritage, cultures, and quality of life of the diverse population of Northwest residents. There is medium confidence that adaptation and informed management, especially culturally appropriate strategies, will increase the resilience of the region’s natural capital.
' evidence: "Since the Third National Climate Assessment, there have been significant contributions within the literature in relation to climate impacts to Northwest communities, with specific focus on how values and activities, such as recreation, iconic wildlife, management, and tribal and Indigenous cultures, will likely be impacted.
Wildlife are projected to have diverse responses to climate change.{{< tbib '94' '28638cf2-7042-48cf-8a30-7f45b405aefb' >}},{{
Multiple studies also demonstrate that climate change impacts will likely affect other iconic, Northwest species. Wildfires will affect berries, roots, and plants;{{< tbib '85' '6848eec2-534b-4629-967c-53d8530089a3' >}},{{
Salmon is one of the most iconic Northwest species and important First Foods for Tribes. Salmon are at high risk to climate change because of decreasing summer flows due to changes in seasonal precipitation and reduced snowpack,{{< tbib '284' 'f8d978b8-85d3-47ea-9a90-543650d83156' >}},{{
There are multiple lines of evidence verifying that reduced snowfall and snowpack in the future will adversely impact winter and snow-based recreation, including a reduction in ski visitation rates.{{< tbib '19' 'b1729fa8-3fbf-4311-a2d0-e0b36ccb9fb6' >}},{{
Adaptation and management strategies in response to climate impacts on the natural capital and Northwest heritage are extremely varied across the region. Many tribes have begun managing First Foods and other important cultural resources through climate change vulnerability assessments and adaptation plans that incorporate both traditional knowledge and western science.{{< tbib '85' '6848eec2-534b-4629-967c-53d8530089a3' >}},{{
This assessment focuses on different aspects of the interaction between humans, the natural environment, and climate change, including reliance on natural resources for livelihoods, the less tangible values of nature, the built environment, health, and frontline communities. Therefore, the author team required a depth and breadth of expertise that went beyond climate change science and included social science, economics, health, tribes and Indigenous people, frontline communities, and climate adaptation, as well as expertise in agriculture, forestry, hydrology, coastal and ocean dynamics, and ecology. Prospective authors were nominated by their respective agencies, universities, organizations, or peers. All prospective authors were interviewed with respect to the qualifications, and selected authors committed to remain part of the team for the duration of chapter development.
The chapter was developed through technical discussions of relevant evidence and expert deliberation by the report authors at workshops, weekly teleconferences, and email exchanges. The author team, along with the U.S. Global Change Research Program (USGCRP), also held stakeholder meetings in Portland and Boise to solicit input and receive feedback on the outline and draft content under consideration. A series of breakout groups during the stakeholder meetings provided invaluable feedback that is directly reflected in how the Key Messages were shaped with respect to Northwest values and the intersection between humans, the natural environment, and climate change. The authors also considered inputs and comments submitted by the public, interested stakeholders, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. For additional information on the overall report process, see Appendix 1: Process. The author team also engaged in targeted consultations during multiple exchanges with contributing authors for other chapters, who provided additional expertise on subsets of the Traceable Accounts associated with each Key Message.
The climate change projections and scenarios used in this assessment have been widely examined and presented elsewhere{{< tbib '11' '07aed96a-e0e8-47dd-81d3-cdff5a6e261c' >}},{{
Climate change and extreme events are already endangering the well-being of a wide range of wildlife, fish, and plants (high confidence), which are intimately tied to tribal subsistence culture (very high confidence) and popular outdoor recreation activities (high confidence). Climate change is projected to continue to have adverse impacts on the regional environment (very likely), with implications for the values, identity, heritage, cultures, and quality of life of the region’s diverse population (high confidence). Adaptation and informed management, especially culturally appropriate strategies, will likely increase the resilience of the region’s natural capital (medium confidence).
' uncertainties: "There is strong evidence to suggest that recreational opportunities are an important quality of the Northwest,{{< tbib '87' '7a666151-302c-4d04-9658-b80816eeec98' >}} but there is uncertainty around the perceived importance of future recreation opportunities’ prioritization in people’s quality of life despite the direct reduction of many recreational opportunities.{{< tbib '127' '84baf9f1-d4b2-491f-8bde-d03168080fa5' >}}
The effects of climate change on game species are uncertain, with large potential forcing in both directions and a lack of information on which processes will dominate consequences for game species and how managers might be able to effectively adapt to changing climate.
" uri: /report/nca4/chapter/northwest/finding/key-message-24-2 url: ~ - chapter_identifier: northwest confidence: "There is very high confidence in the link between extreme events and infrastructure impacts. Most of the existing vulnerability assessments in this region, as well as those at larger spatial scales, emphasize extreme events as a key driver of past impacts. Most infrastructure is planned and designed to withstand events of a specified frequency and magnitude (for example, the 100-year flood, design storms), underscoring the importance of extreme events to our assumptions about infrastructure reliability and function. There is high confidence that rising temperatures, increases in heavy rainfall, and hydrologic changes are projected for the region.{{< tbib '5' 'e450ba2c-db69-43c8-8af4-e0c8ce7c8f2f' >}},{{
Impacts discussed in this chapter (e.g., WSDOT 2014, ODOT and OHA 2016, Withycomb 2017, US Climate Resilience Toolkit 2017{{< tbib '129' 'ce288ad6-4610-400a-805b-fc5e59d20c32' >}},{{
There is a growing body of evidence suggesting that climate change will likely increase the frequency and/or intensity of extreme events such as flooding, landslides, drought, wildfire, and heat waves.{{< tbib '27' '2ca19a87-6e16-41d2-8767-19767e5a74d1' >}},{{
Infrastructure redundancy is widely accepted as a means to enhance system reliability. Multiple investigations cite the importance of system redundancy for transportation, energy, and water supply.{{< tbib '136' '3dd8a56b-03bf-40b4-8b09-6d202e75e901' >}},{{
This assessment focuses on different aspects of the interaction between humans, the natural environment, and climate change, including reliance on natural resources for livelihoods, the less tangible values of nature, the built environment, health, and frontline communities. Therefore, the author team required a depth and breadth of expertise that went beyond climate change science and included social science, economics, health, tribes and Indigenous people, frontline communities, and climate adaptation, as well as expertise in agriculture, forestry, hydrology, coastal and ocean dynamics, and ecology. Prospective authors were nominated by their respective agencies, universities, organizations, or peers. All prospective authors were interviewed with respect to the qualifications, and selected authors committed to remain part of the team for the duration of chapter development.
The chapter was developed through technical discussions of relevant evidence and expert deliberation by the report authors at workshops, weekly teleconferences, and email exchanges. The author team, along with the U.S. Global Change Research Program (USGCRP), also held stakeholder meetings in Portland and Boise to solicit input and receive feedback on the outline and draft content under consideration. A series of breakout groups during the stakeholder meetings provided invaluable feedback that is directly reflected in how the Key Messages were shaped with respect to Northwest values and the intersection between humans, the natural environment, and climate change. The authors also considered inputs and comments submitted by the public, interested stakeholders, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. For additional information on the overall report process, see Appendix 1: Process. The author team also engaged in targeted consultations during multiple exchanges with contributing authors for other chapters, who provided additional expertise on subsets of the Traceable Accounts associated with each Key Message.
The climate change projections and scenarios used in this assessment have been widely examined and presented elsewhere{{< tbib '11' '07aed96a-e0e8-47dd-81d3-cdff5a6e261c' >}},{{
Existing water, transportation, and energy infrastructure already face challenges from flooding, landslides, drought, wildfire, and heat waves (very high confidence). Climate change is projected to increase the risks from many of these extreme events, potentially compromising the reliability of water supplies, hydropower, and transportation across the region (likely, high confidence). Isolated communities and those with systems that lack redundancy are the most vulnerable (likely, medium confidence). Adaptation strategies that address more than one sector, or are coupled with social and environmental co-benefits, can increase resilience (high confidence).
' uncertainties: 'Many analyses and anecdotal evidence link the risk of infrastructure disruption or failure to extreme events. However, the attribution of specific infrastructure impacts to climate variability or climate change remains a challenge. In many cases, infrastructure is subject to multiple climate and non-climate stressors. Non-climate stressors common to many parts of the region include increases in demand or usage from growing populations and changes in land use or development. In addition, much infrastructure across the region is beyond its useful lifetime or may not be in a state of good repair. These factors typically enhance sensitivity to many types of stressors but add uncertainty when trying to draw a direct connection between climate and infrastructure impacts.
Demographic shifts remain an important uncertainty when assessing future infrastructure impacts as well as the relative importance of certain types of infrastructure. Migration to and within the region can fluctuate on timescales shorter than those of climate change. As people move, the relative importance of different types of infrastructure are likely to change, as are the consequences of impacts.
Lastly, there is considerable uncertainty in quantitatively assessing the role of redundancy in minimizing or managing impacts. Metrics for determining the extent to which networking or emergency/backup systems yield adaptive capacity are not currently available at the regional scale.
' uri: /report/nca4/chapter/northwest/finding/key-message-24-3 url: ~ - chapter_identifier: northwest confidence: 'There is high confidence that there will be increased hazards and epidemics, which will very likely disrupt local economies, food systems, and exacerbate chronic health risks, especially among populations most at risk. There is high confidence that these acute hazards will increase due to future climate conditions and will very likely increase the demand on organizations and volunteers that respond and form the region’s social safety net. There is medium confidence that mitigation investments can help counterbalance these risks and likely result in health co-benefits for the region.
' evidence: "Cascading hazards could occur in any season; however, the summer months pose the biggest health challenges. For example, wildfire could occur at the same time as extreme heat and could damage electrical distribution systems, thereby simultaneously exposing people to smoke and high temperatures without the ability to pump water, filter air, or control indoor temperatures. Although some work is being done to prepare, responses to emergency incidents continue to show that there are considerable gaps in our medical and public health systems.{{< tbib '315' '4774f70f-d9c5-43a7-9561-ef771165e5b9' >}} Public health departments are in place to track, monitor, predict, and develop response tactics to disease outbreaks or other health threats. In the case of cascading hazards, the public health system has a role in communicating risks to the public as well as strategies for self-care and sheltering-in-place during a crisis. Unfortunately, local health departments report inadequate capacity to respond to local climate change-related health threats, mainly due to budget constraints.{{< tbib '316' 'f82a2e76-95bb-4a33-8877-8c16ca217397' >}} Hospitals in the United States routinely operate at or above capacity. Large numbers of emergency rooms are crowded with admitted patients awaiting placement in inpatient beds, and hospitals are diverting more than half a million ambulances per year due to emergency room overcrowding.{{< tbib '317' '3c69fb3a-7bcd-4acb-93a2-5dbf687d8491' >}}
Existing environmental health risks are expected to be exacerbated by future climate conditions,{{< tbib '187' 'b1577125-f789-49e6-9656-c40ed932184a' >}} yet over 95% of local health departments in Oregon reported having only partial-to-minimal ability to identify and address environmental health hazards.{{< tbib '194' '796714bc-3fbc-471a-9c93-fbee657006a9' >}} The capacity of our public health systems is largely inadequate and unable to meet basic responsibilities to protect the health and safety of people in the Northwest.{{< tbib '162' 'f1ca2352-7158-4312-9c4b-3d1189c1ad10' >}},{{
Socioeconomic income levels can be a predictor of environmental health outcomes in the future.{{< tbib '187' 'b1577125-f789-49e6-9656-c40ed932184a' >}},{{
Climate mitigation strategies can in some cases have substantial health co-benefits, with evidence pointing toward active transportation{{< tbib '319' '50e17b29-8313-4a48-95e9-cdca2241f4ea' >}} and green infrastructure improvements.{{< tbib '320' 'd1845478-f491-4533-8ef3-bad72ef5282d' >}} This evidence of health co-benefits provides an additional and immediate rationale for reductions in greenhouse gas emissions beyond that of climate change mitigation alone. Recognition that mitigation strategies can have substantial benefits for both health and climate protection offers the possibility of strategies that are potentially both more cost effective and socially attractive than are those that address these priorities independently.{{< tbib '321' '25181456-7f49-4348-8ce8-55e4def0e02b' >}} The Oregon Health Authority’s Climate Smart Strategy Health Impact Assessment found that almost all climate mitigation policies under consideration by the Metro Regional Government could improve health, and that certain policy combinations were more beneficial, namely those that reduced vehicle miles traveled.{{< tbib '322' '62f522a8-bb4a-44a3-89a4-2862e6cd2981' >}} For example, according to 2009 data available on the National Environmental Public Health Tracking Network, a 10% reduction in PM2.5 could prevent more than 400 deaths per year in a highly populated county and about 1,500 deaths every year in the state of California alone. Working across sectors to incorporate a health promotion approach in the design and development of built environment components could mitigate climate change, promote adaptation, and improve public health.{{< tbib '323' 'd01a3234-774c-4ea8-bbc3-f7fd726699bb' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/northwest/finding/key-message-24-4.yaml identifier: key-message-24-4 ordinal: 4 process: "This assessment focuses on different aspects of the interaction between humans, the natural environment, and climate change, including reliance on natural resources for livelihoods, the less tangible values of nature, the built environment, health, and frontline communities. Therefore, the author team required a depth and breadth of expertise that went beyond climate change science and included social science, economics, health, tribes and Indigenous people, frontline communities, and climate adaptation, as well as expertise in agriculture, forestry, hydrology, coastal and ocean dynamics, and ecology. Prospective authors were nominated by their respective agencies, universities, organizations, or peers. All prospective authors were interviewed with respect to the qualifications, and selected authors committed to remain part of the team for the duration of chapter development.
The chapter was developed through technical discussions of relevant evidence and expert deliberation by the report authors at workshops, weekly teleconferences, and email exchanges. The author team, along with the U.S. Global Change Research Program (USGCRP), also held stakeholder meetings in Portland and Boise to solicit input and receive feedback on the outline and draft content under consideration. A series of breakout groups during the stakeholder meetings provided invaluable feedback that is directly reflected in how the Key Messages were shaped with respect to Northwest values and the intersection between humans, the natural environment, and climate change. The authors also considered inputs and comments submitted by the public, interested stakeholders, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. For additional information on the overall report process, see Appendix 1: Process. The author team also engaged in targeted consultations during multiple exchanges with contributing authors for other chapters, who provided additional expertise on subsets of the Traceable Accounts associated with each Key Message.
The climate change projections and scenarios used in this assessment have been widely examined and presented elsewhere{{< tbib '11' '07aed96a-e0e8-47dd-81d3-cdff5a6e261c' >}},{{
Organizations and volunteers that make up the Northwest’s social safety net are already stretched thin with current demands (very likely, high confidence). Healthcare and social systems will likely be further challenged with the increasing frequency of acute events, or when cascading events occur (very likely, high confidence). In addition to an increased likelihood of hazards and epidemics, disruptions in local economies and food systems are projected to result in more chronic health risks (very likely, medium confidence). The potential health co-benefits of future climate mitigation investments could help to counterbalance these risks (likely, medium confidence).
' uncertainties: 'Preparing and responding to cascading hazards is complex and involves many organizations outside of the medical and public health systems. There is not a common set of metrics or standards for measuring surge capacity and emergency preparedness across the region.
There is uncertainty in whether domestic migration will place further stress on social safety net systems.
' uri: /report/nca4/chapter/northwest/finding/key-message-24-4 url: ~ - chapter_identifier: northwest confidence: 'There is very high confidence that frontline communities are the first to be affected by the impacts of climate change. Due to their enhanced sensitivity to changing conditions, direct reliance on natural resources, place-based limits, and lack of financial and political capital, it is very likely that they will face the biggest climate challenges in the region. However, there is a significant amount of uncertainty in how individuals and individual communities will respond to these changing conditions, and responses will likely differ between states, communities, and even neighborhoods. Thus, it is the complex interaction between the climate exposures and the integrated social-ecological systems as well as the surrounding policy and response environment that will ultimately determine the challenges these communities face.
' evidence: "Multiple lines of research have shown that the impacts of extreme weather events and climate change depend not only on the climate exposures but also on the sensitivity and adaptive capacity of the communities being exposed to those changes.{{< tbib '187' 'b1577125-f789-49e6-9656-c40ed932184a' >}},{{
There are multiple lines of evidence that demonstrate that tribes and Indigenous peoples are particularly vulnerable to climate change. Climate stressors, such as sea level rise, ocean acidification, warmer ocean and stream temperatures, wildfires, or droughts, are projected to disproportionately affect tribal and Indigenous well-being and health,{{< tbib '106' '41bc14ce-5dbf-4eb4-90e2-0689a2bc3565' >}},{{
There is limited research on how climate change is projected to impact farmworkers, yet evidence suggests that occupational health concerns, including heat-related concerns{{< tbib '210' '63fe78ee-2eb9-445b-bbb7-e3f72f3993e0' >}},{{
Particularly relevant to economically disadvantaged urban populations, extensive work has been done evaluating and analyzing social vulnerability{{< tbib '211' '796c4617-7dcd-433e-bb0e-805cdab4c136' >}} and applying that work to the Northwest.{{< tbib '195' 'c6bc7876-ad40-4d51-83e5-49816363385c' >}} There has also been work completed considering both relative social vulnerability and environmental health data (see WSDOH 2018{{< tbib '162' 'f1ca2352-7158-4312-9c4b-3d1189c1ad10' >}}).
Strong evidence through reports and case studies demonstrates that tribes are active in increasing their resilience through climate change vulnerability assessments and adaptation plans (see https://www.indianaffairs.gov/WhoWeAre/BIA/climatechange/Resources/Tribes/index.htm and http://tribalclimateguide.uoregon.edu/adaptation-plans for a list of tribal and Indigenous climate resilience programs, reports, and actions) and through regional networks (for example, Pacific Northwest Tribal Climate Change Network, Affiliated Tribes of Northwest Indians, Northwest Indian Fisheries Commission, Columbia River Inter-Tribal Fish Commission, Point No Point Treaty Council, Upper Snake River Tribes Foundation).
There are also many community organizations across the region focusing on engaging, involving, and empowering frontline communities, including communities of color, immigrants, tribes and Indigenous peoples, and others to design plans and policies that are meaningful (for example, Front and Centered, Got Green, Puget Sound Sage, Coalition of Communities of Color).
" href: https://data.globalchange.gov/report/nca4/chapter/northwest/finding/key-message-24-5.yaml identifier: key-message-24-5 ordinal: 5 process: "This assessment focuses on different aspects of the interaction between humans, the natural environment, and climate change, including reliance on natural resources for livelihoods, the less tangible values of nature, the built environment, health, and frontline communities. Therefore, the author team required a depth and breadth of expertise that went beyond climate change science and included social science, economics, health, tribes and Indigenous people, frontline communities, and climate adaptation, as well as expertise in agriculture, forestry, hydrology, coastal and ocean dynamics, and ecology. Prospective authors were nominated by their respective agencies, universities, organizations, or peers. All prospective authors were interviewed with respect to the qualifications, and selected authors committed to remain part of the team for the duration of chapter development.
The chapter was developed through technical discussions of relevant evidence and expert deliberation by the report authors at workshops, weekly teleconferences, and email exchanges. The author team, along with the U.S. Global Change Research Program (USGCRP), also held stakeholder meetings in Portland and Boise to solicit input and receive feedback on the outline and draft content under consideration. A series of breakout groups during the stakeholder meetings provided invaluable feedback that is directly reflected in how the Key Messages were shaped with respect to Northwest values and the intersection between humans, the natural environment, and climate change. The authors also considered inputs and comments submitted by the public, interested stakeholders, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. For additional information on the overall report process, see Appendix 1: Process. The author team also engaged in targeted consultations during multiple exchanges with contributing authors for other chapters, who provided additional expertise on subsets of the Traceable Accounts associated with each Key Message.
The climate change projections and scenarios used in this assessment have been widely examined and presented elsewhere{{< tbib '11' '07aed96a-e0e8-47dd-81d3-cdff5a6e261c' >}},{{
Communities on the front lines of climate change experience the first, and often the worst, effects. Frontline communities in the Northwest include tribes and Indigenous peoples, those most dependent on natural resources for their livelihoods, and the economically disadvantaged (very high confidence). These communities generally prioritize basic needs, such as shelter, food, and transportation (high confidence); frequently lack economic and political capital; and have fewer resources to prepare for and cope with climate disruptions (very likely, very high confidence). The social and cultural cohesion inherent in many of these communities provides a foundation for building community capacity and increasing resilience (likely, medium confidence).
' uncertainties: "Actual climate change related vulnerabilities will vary by community and neighborhood.{{< tbib '187' 'b1577125-f789-49e6-9656-c40ed932184a' >}},{{
The secondary and tertiary impacts of changing climate conditions are less well understood. For example, climate change may increase the amount and frequency of pesticides used, and the variety of products used to manage crop diseases, pests, and competing weeds.{{< tbib '328' 'c0419502-0517-447b-886f-ece5ec4cda6c' >}} This is likely to increase farmworker exposure to pesticides and ultimately affect their health and well-being. Further, it is unclear how the altered timing of agricultural management of key crops across the United States (for example, the timing of cherry picking) due to increased temperatures and altered growing seasons may influence the demand for farmworker labor, particularly migrant labor, and how this might impact their livelihoods and occupational health.
There is emerging evidence that there are overlaps between environmental justice concerns and climate change impacts on these communities,{{< tbib '233' 'e5aac477-6382-425b-9610-4a288438cd25' >}},{{
No systematic catalogue of the actions and efforts of frontline communities in the region to address their climate-related challenges exists. Thus, at this point, most examples of adaptation and climate preparedness are anecdotal, but these examples suggest an increasing trend to link adaptation efforts that simultaneously address both climate and equity concerns. However, this approach is still used sporadically based on the interests, needs, and resources of the communities.
" uri: /report/nca4/chapter/northwest/finding/key-message-24-5 url: ~ - chapter_identifier: southwest confidence: "The very high confidence in historical droughts derives from the detection and attribution analyses of temperature increases, snow decreases, and soil moisture decreases that have documented hydrologic droughts in California and the Colorado River Basin due to anthropogenic climate change and the conclusions of the Climate Science Special Report (CSSR), Volume I of the Fourth National Climate Assessment.{{< tbib '74' 'a29b612b-8c28-4c93-9c18-19314babce89' >}} The very high confidence in drought projections derives from the multitude of analyses projecting drought in the Southwest under a range of emissions scenarios and the conclusions of the CSSR.{{< tbib '74' 'a29b612b-8c28-4c93-9c18-19314babce89' >}} Only medium confidence is found for flood projections due to lack of consensus in the model projections of precipitation. Increasingly arid conditions and the potential for increased water use by people lead to an assessment of high confidence in the need for new ways to address increasing risks of water scarcity. The actual frequency and duration of water supply disruptions will depend on the preparation of water resource managers with drought and flood plans, the flexibility of water resource managers to implement or change those plans in response to altered circumstances,{{< tbib '481' 'da714e9f-808c-4aae-8d24-aef041988322' >}} the availability of funding to make infrastructure more resilient, and the magnitude and frequency of climate extremes.
" evidence: "Research has found that hotter temperatures can make hydrologic droughts more severe. The unprecedented droughts in the Colorado River Basin and California showed that increased temperatures from climate change intensified the severity of the drought.{{< tbib '13' 'a42c4f5e-f16b-4196-af05-61f117e0491d' >}},{{
The authors examined the scientific literature in their areas of expertise. The team placed the highest weight on scientific articles published in refereed peer-reviewed journals. Other sources included published books, government technical reports, and, for data, government websites. The U.S. Global Change Research Program issued a public call for technical input and provided the authors with the submissions. The University of Arizona Center for Climate Adaptation Science and Solutions organized the Southwest Regional Stakeholder Engagement Workshop on January 28, 2017, with over 70 participants at the main location in Tucson, AZ, and dozens of participants in Albuquerque, NM, Boulder, CO, Davis, CA, Los Angeles, CA, Reno, NV, and Salt Lake City, UT, all connected by video. Participants included scientists and managers. The author team met the following day for their only meeting in person. Subsequently, authors held discussions in regular teleconferences. Many chapter authors met at the all-author meeting March 26–28, 2018, in Bethesda, MD.
' report_identifier: nca4 statement: 'Water for people and nature in the Southwest has declined during droughts, due in part to human-caused climate change (very high confidence). Intensifying droughts (very high confidence) and occasional large floods (medium confidence), combined with critical water demands from a growing population, deteriorating infrastructure, and groundwater depletion, suggest the need for flexible water management techniques that address changing risks over time (high confidence), balancing declining supplies with greater demands.
' uncertainties: "Projecting future streamflow and hydrologic characteristics in a basin contains many uncertainties. These differences arise because of uncertainty in temperature and precipitation projections due to differences among global climate models (GCMs), uncertainty in regional downscaling, uncertainty in hydrological modeling, and differences in emissions, aerosols, and other forcing factors. Another important uncertainty is differences in the hemispheric and regional-scale atmospheric circulation patterns produced by different GCMs, which generate different levels of snow loss in different model simulations. A key uncertainty is the wide range in projections of future precipitation across the Southwest;{{< tbib '105' '9d8a98fa-0338-486a-b902-cd02d43cae87' >}} some projections of higher-than-average precipitation in the northern parts of the Southwest could roughly offset declines in warm-season runoff associated with warming.{{< tbib '105' '9d8a98fa-0338-486a-b902-cd02d43cae87' >}}
Detection is the finding of statistically significant changes different from natural cycles. Attribution is the analysis of the relative contribution of different causes and whether greenhouse gas emissions from human sources outweigh other factors. Attribution of extreme events, such as the recent California drought to climate change, is an area of emerging science. On the one hand, Seager et al. (2015){{< tbib '58' '4ca5a43c-5fbe-4cb0-8a7d-7ee3acafd7c0' >}} concluded that the California drought was primarily driven by natural precipitation variability. Sea surface temperature anomalies helped set up the high-pressure ridge over California that blocked moisture from moving inland. On the other hand, Diffenbaugh et al. (2015),{{< tbib '56' '89e08a41-6091-45fa-a92e-6168a90a8151' >}} Williams et al. (2015),{{< tbib '14' 'ba57f86f-c42f-4bba-83f6-676d6875c176' >}} and Berg and Hall (2017){{< tbib '55' '2d7d840f-37b6-4484-ba59-aa2d537a8c7c' >}} concluded that high temperatures from climate change drove record-setting surface soil moisture deficits that made the drought more severe than it would have been without climate change. Storage of increased precipitation in soils may partially offset increased evaporation, possibly making drought less likely.{{< tbib '480' '4fbaaa13-99d2-43df-93db-2be546f18892' >}}
In addition to the uncertainties in regional climate and hydrology projections and attribution studies, other uncertainties include potential changes in water management strategies and responses to accommodate the new changing baseline. Additionally, external uncertainties can impact water use in the region via legal, economic, and institutional options for augmenting existing supplies, adding underground storage and recovery infrastructure, and fostering further water conservation, changes in unresolved water rights, and changes to local, state, tribal, regional and national policies related to the balance of agricultural, ecosystem, and urban water use.
" uri: /report/nca4/chapter/southwest/finding/key-message-25-1 url: ~ - chapter_identifier: southwest confidence: 'Field evidence provides high confidence that human-caused climate change has increased wildfire, tree death, and species range shifts. Projections consistently indicate that continued climate change under higher emissions could increase the future vulnerability of ecosystems, but that reducing emissions and increasing fire management would reduce the vulnerability, providing high confidence in positive benefits of these actions.
' evidence: "Scientific research in the Southwest has provided many cases of detection and attribution of historical climate change impacts. Detection is the finding of statistically significant changes different from natural cycles. Attribution is the analysis of the relative contribution of different causes and whether greenhouse gas emissions from human sources outweigh other factors. Published field research has detected ecological changes in the Southwest and attributed much of the causes of the changes to climate change. Wildfire across the western United States doubled from 1984 to 2015, compared to what would have burned without climate change, based on analyses of eight fuel aridity metrics calculated from observed data, historical observed temperature, and historical modeled temperature from global climate models.{{< tbib '7' 'de4a77df-03ba-4319-a13f-7fdefbb353a5' >}} The increased heat has intensified droughts in the Southwest,{{< tbib '13' 'a42c4f5e-f16b-4196-af05-61f117e0491d' >}},{{
Cutting emissions through energy conservation and renewable energy can reduce ecological vulnerabilities. Under high emissions, projected climate change could triple burned area in the Sierra Nevada, but under low emissions, fire could increase just slightly.{{< tbib '173' '8dfecf8b-f8a8-4f03-8d68-551b13794a1d' >}} Projections of biome shifts{{< tbib '213' '37982de0-0e01-476f-b522-b8162d709134' >}},{{
The authors examined the scientific literature in their areas of expertise. The team placed the highest weight on scientific articles published in refereed peer-reviewed journals. Other sources included published books, government technical reports, and, for data, government websites. The U.S. Global Change Research Program issued a public call for technical input and provided the authors with the submissions. The University of Arizona Center for Climate Adaptation Science and Solutions organized the Southwest Regional Stakeholder Engagement Workshop on January 28, 2017, with over 70 participants at the main location in Tucson, AZ, and dozens of participants in Albuquerque, NM, Boulder, CO, Davis, CA, Los Angeles, CA, Reno, NV, and Salt Lake City, UT, all connected by video. Participants included scientists and managers. The author team met the following day for their only meeting in person. Subsequently, authors held discussions in regular teleconferences. Many chapter authors met at the all-author meeting March 26–28, 2018, in Bethesda, MD.
' report_identifier: nca4 statement: 'The integrity of Southwest forests and other ecosystems and their ability to provide natural habitat, clean water, and economic livelihoods have declined as a result of recent droughts and wildfire due in part to human-caused climate change (high confidence). Greenhouse gas emissions reductions, fire management, and other actions can help reduce future vulnerabilities of ecosystems and human well-being (high confidence).
' uncertainties: "Because climate model projections often diverge on whether precipitation may increase or decrease, two broad types of fire futures{{< tbib '152' '391560e0-40c1-4f9d-b063-e87d18c87e02' >}} could be 1) dry-fire future—hotter and drier climate, increased fire frequency, fire limited by vegetation, potential biome change of forest to grassland after a fire due to low natural regeneration, and high carbon emissions; or 2) intense-fire future—hotter and wetter climate, more vegetation, increased fire frequency and intensity, fire limited by climate, and higher carbon emissions. These two broad categories each encompass a range of fire conditions. On the ground, gradients of temperature, precipitation, and climate water deficit (difference between precipitation and actual evapotranspiration) generate gradients of fire regimes. Because climate change, vegetation, and ignitions vary across the landscape, potential fire frequency shows high spatial variability. Therefore, future fire types could appear in patches across the landscape, with different fire future types manifesting themselves in adjacent forest patches. Changes in aridity may shift some plant and animal species ranges downslope to favorable combinations of available moisture and suitable temperature, rather than upslope.{{< tbib '484' '9743c446-fef0-44f4-82bd-7f2ff1614205' >}} Plants and animals may respond to changing climate, and have been shown to do so, through range shifts, phenology shifts, biological evolution, or local extirpation. Thus, no single expected response pattern exists.{{< tbib '224' '820ced23-71ae-4607-8353-74e3881db2a1' >}}
" uri: /report/nca4/chapter/southwest/finding/key-message-25-2 url: ~ - chapter_identifier: southwest confidence: 'Field measurements at numerous locations have detected sea level rise, ocean warming, ocean acidification, and ocean hypoxia. Multiple model-based analyses have attributed these changes to human-caused climate change, giving high confidence to these impacts of climate change.
' evidence: "At the Golden Gate Bridge, San Francisco, sea level rose 9 ± 0.4 inches (22 ± 1 cm) from 1854 to 2016,{{< tbib '236' '8e1ab38d-5d31-4a6a-8ad6-e06fe74a4aa1' >}} and at San Diego, 9 ± 0.8 inches (24 ± 2 cm) from 1906 to 2016.{{< tbib '237' '1f19738a-f4ec-4a51-8478-b88163d6dea6' >}} Analyses of these gauges and hundreds around the world show a statistically significant increase in global mean sea level{{< tbib '238' '94a8514e-063e-45ef-b893-11c82b49a597' >}},{{
The authors examined the scientific literature in their areas of expertise. The team placed the highest weight on scientific articles published in refereed peer-reviewed journals. Other sources included published books, government technical reports, and, for data, government websites. The U.S. Global Change Research Program issued a public call for technical input and provided the authors with the submissions. The University of Arizona Center for Climate Adaptation Science and Solutions organized the Southwest Regional Stakeholder Engagement Workshop on January 28, 2017, with over 70 participants at the main location in Tucson, AZ, and dozens of participants in Albuquerque, NM, Boulder, CO, Davis, CA, Los Angeles, CA, Reno, NV, and Salt Lake City, UT, all connected by video. Participants included scientists and managers. The author team met the following day for their only meeting in person. Subsequently, authors held discussions in regular teleconferences. Many chapter authors met at the all-author meeting March 26–28, 2018, in Bethesda, MD.
' report_identifier: nca4 statement: 'Many coastal resources in the Southwest have been affected by sea level rise, ocean warming, and reduced ocean oxygen—all impacts of human-caused climate change (high confidence)—and ocean acidification resulting from human emissions of carbon dioxide (high confidence). Homes and other coastal infrastructure, marine flora and fauna, and people who depend on coastal resources face increased risks under continued climate change (high confidence).
' uncertainties: "Catastrophic rapid loss of Antarctic and Greenland ice sheets could increase sea level more rapidly. Sea level rise at individual locations depends on the form of the seafloor (bathymetry) and other local conditions. Climate change impacts compound overfishing and make fish populations more vulnerable. Potential economic changes in California’s coastal and marine-based economies are subject to many different environmental and socioeconomic factors.
The full complexity of ecological responses to ocean acidification in combination with other stresses in California marine waters is currently unknown. Food supply for marine species,{{< tbib '487' 'cf677518-2ff0-4462-8d41-e48e8655ba18' >}} natural variation in resilience,{{< tbib '488' '04a02114-e2b5-4c87-8c34-5658bc4f3c05' >}},{{
The documented human-caused increase in temperature is a key driver of regional impacts to snow, soil moisture, forests, and wildfire, which affect Indigenous peoples, other frontline communities, and all of civil society. Case study evidence, using Indigenous and Western scientific observations, oral histories, traditional knowledge and wisdom (e.g., Ferguson et al. 2016{{< tbib '493' 'd630a483-2475-4fbb-b942-e5068ac04971' >}}), suggests that climate change is affecting the health, livelihoods, natural and cultural resources, practices, and spiritual well-being of Indigenous communities and peoples in the Southwest (e.g., Redsteer et al. 2011, 2013; Wotkyns 2011; Cozzetto et al. 2013; Gautam et al. 2013; Navajo Nation Department of Fish and Wildlife 2013; Nania and Cozzetto et al. 2014; Sloan and Hostler 2014; Redsteer and Fordham 2017{{< tbib '44' '85923ac2-22e6-4265-9d70-1887132abfce' >}},{{
Abundant evidence and strong agreement among sources exist regarding current impacts of climate change in the region. Impacts of climate change on the food sources, natural resources-based livelihoods, cultural resources and practices, and spiritual health and well-being of Southwest Indigenous peoples are supported, in part, by evidence of regional temperature increases,{{< tbib '23' '29960c69-6168-4fb0-9af0-d50bdd91acd3' >}},{{
Impacts specific to Indigenous peoples include: 1) declining surface soil moisture, higher temperatures, and evaporation converge with oak trees’ decreased resilience,{{< tbib '285' 'd04b2c86-5ca0-42e0-9792-2f319c15cd7e' >}} diminished acorn production, and fire and pest threat to reduce the availability and quality of acorns for tribal food consumption and cultural purposes;{{< tbib '306' 'debdf209-4050-4706-965c-09cff7ec353b' >}} and 2) declining vegetation, higher temperatures, diminished snow, and soil desiccation have caused dust storms and more mobile dunes on some Navajo and Hopi lands, resulting in damaged infrastructure and grazing lands and loss of valued native plant habitat.{{< tbib '44' '85923ac2-22e6-4265-9d70-1887132abfce' >}},{{
Multiple projections of climate and hydrological changes show potential future change and disruption to the ecosystems on which Indigenous peoples depend for their natural resources-based livelihoods, health, cultural practices, and traditions. These include projections of increased temperatures and heat extremes;{{< tbib '24' 'acbb7b12-c119-4c42-8a80-c2555964db4c' >}} longer, more severe, and more frequent drought;{{< tbib '13' 'a42c4f5e-f16b-4196-af05-61f117e0491d' >}},{{
Evidence of specific future disruptions to traditional food sources from forests and oceans mostly relies upon inferences, based on projections of changing seasonality and associated phenological or ecosystem responses{{< tbib '298' '6848eec2-534b-4629-967c-53d8530089a3' >}},{{
Abundant evidence exists of autonomous adaptation strategies, projects, and actions, rooted in traditional environmental knowledge and practices or integration of diverse knowledge systems to inform ecological management to support adaptation and ecosystem resilience.{{< tbib '490' '953476ae-1357-48a5-99d8-1daf963f0a3c' >}},{{
In response to the current and future projected climate changes and ecosystem disruptions, a number of tribes in the Southwest are planning and implementing energy efficient and renewable energy projects.{{< tbib '327' 'fda7d18b-acc5-46fc-9863-3b4ac6a609be' >}},{{
Several tribes in the Southwest are developing climate change adaptation plans to address the current climate-related impacts and prepare for future projected climate changes. The Santa Ynez Band of Chumash Indians, which is working towards an integrated energy and climate action plan, the Yurok Tribe, the Gila River Indian Community, and the Tohono O’odham Nation are among the first tribes in the region to develop climate adaptation and resilience plans, which reflects a nationwide gap or need for further tribal adaptation plan development. Lack of capacity and funds has hindered progress in moving from planning to implementation, which is similar to the situation for U.S. cities.{{< tbib '497' '8a61b1a7-bb52-496d-86f7-21911efcf5f8' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/southwest/finding/key-message-25-4.yaml identifier: key-message-25-4 ordinal: 4 process: 'The authors examined the scientific literature in their areas of expertise. The team placed the highest weight on scientific articles published in refereed peer-reviewed journals. Other sources included published books, government technical reports, and, for data, government websites. The U.S. Global Change Research Program issued a public call for technical input and provided the authors with the submissions. The University of Arizona Center for Climate Adaptation Science and Solutions organized the Southwest Regional Stakeholder Engagement Workshop on January 28, 2017, with over 70 participants at the main location in Tucson, AZ, and dozens of participants in Albuquerque, NM, Boulder, CO, Davis, CA, Los Angeles, CA, Reno, NV, and Salt Lake City, UT, all connected by video. Participants included scientists and managers. The author team met the following day for their only meeting in person. Subsequently, authors held discussions in regular teleconferences. Many chapter authors met at the all-author meeting March 26–28, 2018, in Bethesda, MD.
' report_identifier: nca4 statement: 'Traditional foods, natural resource-based livelihoods, cultural resources, and spiritual well-being of Indigenous peoples in the Southwest are increasingly affected by drought, wildfire, and changing ocean conditions (very likely, high confidence). Because future changes would further disrupt the ecosystems on which Indigenous peoples depend (likely, high confidence), tribes are implementing adaptation measures and emissions reduction actions (very likely, very high confidence).
' uncertainties: "Uncertainties in the climate and hydrologic drivers of regional changes affecting Indigenous peoples in the Southwest include 1) differences in projections from multiple GCMs and associated uncertainties related to regional downscaling methods, 2) the way snow is treated in regional modeling,{{< tbib '498' '64014404-d26e-45c7-9b33-8e2253a9ca04' >}} 3) variability in projections of extreme precipitation, and, in particular, 4) uncertainties in summer and fall precipitation projections for the region.{{< tbib '88' 'e8089a19-413e-4bc5-8c4a-7610399e268c' >}} Additional uncertainties exist in sea level rise projections{{< tbib '242' 'a1aee4ba-d4fc-4f92-a74a-e37189c138b5' >}} and, for the California coast, ocean process model projections of acidification, deoxygenation, and warming coastal zone temperatures.{{< tbib '499' '99e25417-f6c0-49f1-87cd-e9af689f3cff' >}} For the most part, Native lands lack instrumental monitoring for weather and climate, which is a barrier for long-term climate-related planning.{{< tbib '493' 'd630a483-2475-4fbb-b942-e5068ac04971' >}}
Complexities arising from the multiple factors affecting ecosystem processes, including tree mortality and fire, often preclude formal detection and attribution studies. Much evidence and agreement among evidence exist regarding the role of hotter temperatures in fire and tree mortality.{{< tbib '7' 'de4a77df-03ba-4319-a13f-7fdefbb353a5' >}},{{
Other uncertainties relate to estimating future vulnerabilities and impacts, which depend, in part, on adjudication of unresolved water rights and the potential development of local, state, regional, tribal, and national policies that may promote or inhibit the development and deployment of adaptation and mitigation strategies.
" uri: /report/nca4/chapter/southwest/finding/key-message-25-4 url: ~ - chapter_identifier: southwest confidence: "Hydrological drought in California reduced hydroelectric generation{{< tbib '335' '8347d2b2-855d-4765-b7a2-6d2a9e0c99f4' >}} and fossil fuel electricity generation efficiencies. Drought and rising temperatures under climate change can reduce the ability of hydropower and fossil fuel electricity generation to meet growing energy use in the Southwest (very likely, very high confidence). Renewable solar and wind energy offers increased electricity reliability, lower water intensity for energy generation, reduced greenhouse gas emissions, and new economic opportunities (likely, high confidence).
" evidence: "Numerous studies link Southwest hydrologic drought with a decline in renewable hydroelectricity generation in the region. Hydroelectric generation depends on runoff to fill reservoirs to maximize generation capacity.{{< tbib '336' '7db8f4ff-81fb-4d22-949a-076aab55aa86' >}},{{
Similarly, low reservoir levels in Lake Mead—which is formed by damming the Colorado River—driven by reduced Colorado River runoff{{< tbib '13' 'a42c4f5e-f16b-4196-af05-61f117e0491d' >}},{{
Fossil fuel generation efficiency depends on the temperature and availability of the external cooling water. Warming could reduce energy efficiency up to 15% across the Southwest by 2100.{{< tbib '91' '8c12cc4c-3448-4055-b7a2-e03ead1c2572' >}} Higher temperatures also increase electric resistance in transmission lines, causing transmission losses of 7% under higher emissions.{{< tbib '344' '673a11a4-4d3c-4303-af82-29de1ca24bd6' >}} Replacing fossil fuel generation with solar power renewables reduces greenhouse gas emissions and water use per unit of electricity generated.{{< tbib '90' '437ba8f2-66cf-44f5-8bea-173c02458858' >}} This supports the assertion that increasing solar energy generation in the Southwest could meet the energy demand no longer being met by hydropower and fossil fuel as well as the expected increase in energy use in the future.
Solar energy production is also an economic opportunity for the region. The energy potential for renewable energy is estimated to range from one-third to over ten times 2013 generation levels from all sources.{{< tbib '502' '2c0c6750-e017-4590-b7aa-e1756bc7854b' >}} The lower range assumes capacity requirements remain at 2013 levels,{{< tbib '502' '2c0c6750-e017-4590-b7aa-e1756bc7854b' >}} but recent data show an upward trend in Southwest energy use.{{< tbib '89' 'ab3cc54d-c74f-4a6d-8746-efa051c2e97e' >}}
The high potential for solar energy projects in the Southwest and the extent of federally owned land in the Southwest (well over half the total surface area for the six-state region) prompted the Bureau of Land Management (BLM) and the U.S. Department of Energy to conduct a programmatic environmental impact analysis of a new Solar Energy Program to further support utility-scale solar energy development on BLM-administered lands.{{< tbib '502' '2c0c6750-e017-4590-b7aa-e1756bc7854b' >}},{{
Solar and renewable energy jobs are increasing. The solar workforce increased 25% in 2016, while wind employment increased 32%.{{< tbib '505' '92b75533-4ebe-4cad-af48-6789b4627f47' >}} Jobs in low-carbon-emission generation systems, including renewables, nuclear, and advanced low-emission natural gas, comprise 45% of all the jobs in the electric power generation and fuels technologies.{{< tbib '505' '92b75533-4ebe-4cad-af48-6789b4627f47' >}} Growing Southwest energy use, competitive prices for renewables, and the renewable energy potential of the Southwest favor the replacement of fossil-fuel-generated energy by renewable solar and wind energy.
" href: https://data.globalchange.gov/report/nca4/chapter/southwest/finding/key-message-25-5.yaml identifier: key-message-25-5 ordinal: 5 process: 'The authors examined the scientific literature in their areas of expertise. The team placed the highest weight on scientific articles published in refereed peer-reviewed journals. Other sources included published books, government technical reports, and, for data, government websites. The U.S. Global Change Research Program issued a public call for technical input and provided the authors with the submissions. The University of Arizona Center for Climate Adaptation Science and Solutions organized the Southwest Regional Stakeholder Engagement Workshop on January 28, 2017, with over 70 participants at the main location in Tucson, AZ, and dozens of participants in Albuquerque, NM, Boulder, CO, Davis, CA, Los Angeles, CA, Reno, NV, and Salt Lake City, UT, all connected by video. Participants included scientists and managers. The author team met the following day for their only meeting in person. Subsequently, authors held discussions in regular teleconferences. Many chapter authors met at the all-author meeting March 26–28, 2018, in Bethesda, MD.
' report_identifier: nca4 statement: 'The ability of hydropower and fossil fuel electricity generation to meet growing energy use in the Southwest is decreasing as a result of drought and rising temperatures (very likely, very high confidence). Many renewable energy sources offer increased electricity reliability, lower water intensity of energy generation, reduced greenhouse gas emissions, and new economic opportunities (likely, high confidence).
' uncertainties: "Climate model projections of the future diverge on whether precipitation may increase or decrease for much of the region, so hydroelectric power changes may exhibit spatial variation. The amount of runoff is a key factor driving the generation potential for hydroelectric power. A key uncertainty is how much hydroelectricity generation will decline. Some projections of higher-than-average precipitation in the northern parts of the Southwest could roughly offset declines in warm-season runoff associated with warming.{{< tbib '105' '9d8a98fa-0338-486a-b902-cd02d43cae87' >}}
Energy demand in the Southwest is increasing, but the rate of growth is uncertain.{{< tbib '506' '561029d5-4494-43bf-98d2-96ad38606588' >}} Changes in energy market prices cause future uncertainty in the future mix of energy sources for the Southwest.{{< tbib '502' '2c0c6750-e017-4590-b7aa-e1756bc7854b' >}} The low cost of natural gas and the competitive cost of solar and wind renewables make it somewhat certain the proportion of the energy generated from these sources will continue to increase and offset reductions in traditional fossil-fuel-generated energy, reducing overall greenhouse gas emissions.{{< tbib '504' '1f8c0eab-9564-4064-bd8e-b98c135744e9' >}} Renewable energy job growth potential is also uncertain and depends on the factors mentioned above.{{< tbib '505' '92b75533-4ebe-4cad-af48-6789b4627f47' >}}
Additionally, daily to multiyear variation in coastal cloud cover affects solar electricity generation potential along the California coast.{{< tbib '507' 'beba4436-bbd0-43c2-bd04-e6000c5e4a27' >}},{{
Since the availability of affordable food around the world depends upon complex trade and transportation networks, the effects of climate change on Southwest food availability, production, and affordability remain highly complex and thereby uncertain and classified with medium confidence. While the viability of rural livelihoods is vulnerable to water shortages and other climate-related risks, rural livelihoods may be supplemented by other nonagricultural income, such as recreation and hunting. The viability of rural livelihoods is highly complex, and risk is, therefore, classified with medium confidence. Crop impacts related to hotter and drier conditions and reduced winter chill periods, caused by climate change, are classified with medium confidence. Not all crops are directly harmed by warming temperatures, and the simulation impacts of reduced chilling hours can produce a fairly wide range of results depending upon model assumptions. Hotter and drier conditions can directly harm livestock via reduced forage quantity and quality and exposure to higher temperatures, conferring a high confidence classification. Projections of future drought and water scarcity portend increased competition for water from other beneficial uses with medium confidence.
' evidence: "Climate change has altered climate factors fundamental to food production and rural livelihoods in the Southwest. Abundant evidence and good agreement in evidence exist regarding regionally increasing temperatures, reduced soil moisture, and effects on regional snowpack and surface water sources.{{< tbib '13' 'a42c4f5e-f16b-4196-af05-61f117e0491d' >}},{{
Elevated temperatures can be associated with failure of some crops, such as warm-season vegetable crops, and reduced yields and/or quality in others.{{< tbib '374' 'c29be9d3-c558-41ec-979c-f8d0c0b6f0e6' >}} Temperatures in California, Nevada, and Arizona are already at the upper threshold for corn{{< tbib '372' '53efddbf-8a1f-44fb-83e2-167fde08c9aa' >}} and rice.{{< tbib '373' 'a7cfed2a-25b6-4d4f-a9dc-49e1568e2aea' >}} While crops grown in some areas might not be viable under hotter conditions, other crops such as olives, cotton, kiwi, and oranges may replace them.{{< tbib '375' '0a8508df-df59-4080-89a2-52bfeaca47e0' >}} In the Southwest, climate change may cause a northward shift in crop production, potentially displacing existing growers and affecting rural communities.{{< tbib '376' '4442506b-fbba-41ea-9cef-1eac88ce2049' >}} Quality of specialty crops, both nutritive and sensory, declines because of increased temperatures and other changes associated with a changing climate,{{< tbib '393' '3baf471f-751f-4d68-9227-4197fdbb6e5d' >}},{{
High ambient temperatures associated with climate change could decrease production of rangeland vegetation across the Southwest,{{< tbib '384' 'aa6f4075-c70e-43f8-969e-b5625ad25449' >}} reducing available forage for livestock. Ranching enterprises across the region have vastly different characteristics that will influence their adaptive capacities.{{< tbib '390' 'c779538d-b066-4e38-8527-ff3f7552f26e' >}}
Local-scale impacts can vary considerably across the region depending upon surface and groundwater availability. Drought causes altered water management, with heavy reliance on a limited groundwater to sustain regional food production.{{< tbib '130' '7aecf6b3-0b12-40d7-8c61-c1b72cc14289' >}} Despite severe localized impacts, losses in total agricultural revenue are buffered by groundwater reliance to offset surface water shortage.{{< tbib '369' '53ceb8c3-f1b8-4cc1-bb65-3268f4f8bb74' >}} Parts of the Southwest have exhausted sustainable use of groundwater resources. When surface water supplies are reduced, farmers shift to increased groundwater pumping, even when pumping raises production costs{{< tbib '371' 'cf96b502-57a2-4b76-bffc-750e1bf668d6' >}}—declining groundwater tables significantly increase pumping costs and require drilling of deeper wells.{{< tbib '130' '7aecf6b3-0b12-40d7-8c61-c1b72cc14289' >}} Continued climate change may reduce aquifer recharge in the southern part of the region 10%–20%.{{< tbib '370' '2042ab8a-6a82-40a2-99ba-7e67babf8ffc' >}} Climate change is projected to cause longer and more severe drought periods that will intensify the uncertainty associated with Southwest water supply and demand. Water-intensive forage crops and the livestock industry are especially vulnerable to climate-related water shortages.{{< tbib '15' 'bf7e284b-6333-477d-883f-23e002742a6c' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/southwest/finding/key-message-25-6.yaml identifier: key-message-25-6 ordinal: 6 process: 'The authors examined the scientific literature in their areas of expertise. The team placed the highest weight on scientific articles published in refereed peer-reviewed journals. Other sources included published books, government technical reports, and, for data, government websites. The U.S. Global Change Research Program issued a public call for technical input and provided the authors with the submissions. The University of Arizona Center for Climate Adaptation Science and Solutions organized the Southwest Regional Stakeholder Engagement Workshop on January 28, 2017, with over 70 participants at the main location in Tucson, AZ, and dozens of participants in Albuquerque, NM, Boulder, CO, Davis, CA, Los Angeles, CA, Reno, NV, and Salt Lake City, UT, all connected by video. Participants included scientists and managers. The author team met the following day for their only meeting in person. Subsequently, authors held discussions in regular teleconferences. Many chapter authors met at the all-author meeting March 26–28, 2018, in Bethesda, MD.
' report_identifier: nca4 statement: 'Food production in the Southwest is vulnerable to water shortages (medium confidence). Increased drought, heat waves, and reduction of winter chill hours can harm crops (medium confidence) and livestock (high confidence); exacerbate competition for water among agriculture, energy generation, and municipal uses (medium confidence); and increase future food insecurity (medium confidence).
' uncertainties: "The impacts of climate change on food production depend upon microclimatology and local-scale environmental, social, and economic resources. While the scientific community relies upon computer models and generalized information to project likely future conditions, unforeseen consequences of warming temperatures, such as those related to pests, pollinators, and pathogens, may be more detrimental than some of the well-documented projections, such as temperature impacts on reduced yields. The effects of increased precipitation supplying the deep root zone may somewhat offset the increase in temperature, so agricultural drought may be less frequent for trees and other crops dependent on deeper soil moisture.{{< tbib '480' '4fbaaa13-99d2-43df-93db-2be546f18892' >}} Scientists are producing more drought- and heat-tolerant cultivars, which may be suitable to production in the projected warmer and more arid climate of the Southwest.
Since food security relies on complex national and international trade networks, how regional climate change may affect local food security is uncertain. Many adaptation options, such as using alternate breeds, crops, planting and harvest dates, and new (sometimes untested) chemicals, may work in certain situations but not others. Thus, predicting impacts to food production in a hotter/drier land is likely to vary by crop and location, necessitating flexibility and adaptive management. Of paramount uncertainty is the impact of water shortage on regional food production as other uses may outcompete producers for limited supplies.
" uri: /report/nca4/chapter/southwest/finding/key-message-25-6 url: ~ - chapter_identifier: southwest confidence: "Evaluation of confidence levels for the assessment of the type and magnitude of observed or projected public health and clinical impacts was based on the strength of evidence underlying the answers to three primary questions:
What characteristics of the region’s historical climate and weather patterns translate directly (for example, extreme heat) or indirectly (for example, higher temperatures fostering ozone formation or the growth and spread of pathogens and vectors) to exposures associated with observed human health risks that are unique to or overrepresented in the Southwest?
Does recent historical evidence indicate that climate and weather patterns have changed, or do climate models project changes over the 21st century, thereby increasing the risk of human exposures and health impacts evaluated under question 1?
What are the determinants of individual and population vulnerability that increase or decrease the risk of an adverse health outcome or affect adaptive capacity? These include factors that affect a) biological susceptibility, b) physical environment and exposure characteristics, and c) social, behavioral, or economic factors.
To the extent possible, the evaluation recognized and accounted for the complex interconnections among these factors, the fact that their relative importance may differ across geographic and temporal scales, and the combined uncertainties of evidence from multiple disciplines (for example, health sciences, climatology, and social or behavioral sciences) that can vary substantially.
The information revealed by answering those questions, gives high confidence that extreme heat will be the dominant driver of exposures that pose the greatest health risks in the Southwest—including direct effects of heat on individuals and indirect effects of heat on air pollution levels. Due to the uncertainties related to the frequency and intensity of human exposures and related to impacts on essential ecosystem services under projected climate change, the statement “Improving public health systems, community infrastructure, and personal health can reduce serious health risks under future climate change” is made with medium confidence. Nevertheless, clinical and public health policy effectiveness assessments show that such improvements can reduce the burden of disease and health risks associated with environmental exposures.
" evidence: "Strong evidence and good agreement among multiple sources and lines of evidence exist, indicating that the Southwest regional temperature may increase, snowpack may decline, soil moisture may decrease, and drought may be prolonged.{{< tbib '14' 'ba57f86f-c42f-4bba-83f6-676d6875c176' >}},{{
Exposure to hotter temperatures and extreme heat events, partly a manifestation of human-caused climate change, already led to heat-associated deaths and illnesses in heat waves in Arizona and California in the early and mid-2000s.{{< tbib '398' 'b3e00a14-a876-44fa-9c1f-836bd53a7f69' >}},{{
Good agreement exists among models that most of the Southwest may become more arid, due to the effect of increasing temperatures on snow, evaporation, and soil moisture.{{< tbib '58' '4ca5a43c-5fbe-4cb0-8a7d-7ee3acafd7c0' >}},{{
Strong evidence exists of the effects of extreme heat on public health in the region (e.g., Knowlton et al. 2009, Oleson et al. 2015, Wilhelmi et al. 2004{{< tbib '400' '7ca0e947-163a-46f3-9274-cea209b94510' >}},{{
Given the proportion of the U.S. population in the Southwest, a disproportionate number of West Nile virus, plague, hantavirus pulmonary syndrome, and Valley fever cases occur in the region.{{< tbib '158' 'd8bd2def-be9b-47e3-84de-199bcd26c31d' >}},{{
Overall, the Southwest is ill-prepared to absorb the additional patient load that would accompany climate change associated disasters.{{< tbib '448' 'e523f9c0-56f9-44ff-b2d9-7debec2a19d0' >}} The American College of Emergency Physicians assigned an overall emergency care grade of C or C+ to three of the six Southwest states, with the others receiving poorer grades, and four of the six states received an F grade for access to emergency care.{{< tbib '448' 'e523f9c0-56f9-44ff-b2d9-7debec2a19d0' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/southwest/finding/key-message-25-7.yaml identifier: key-message-25-7 ordinal: 7 process: 'The authors examined the scientific literature in their areas of expertise. The team placed the highest weight on scientific articles published in refereed peer-reviewed journals. Other sources included published books, government technical reports, and, for data, government websites. The U.S. Global Change Research Program issued a public call for technical input and provided the authors with the submissions. The University of Arizona Center for Climate Adaptation Science and Solutions organized the Southwest Regional Stakeholder Engagement Workshop on January 28, 2017, with over 70 participants at the main location in Tucson, AZ, and dozens of participants in Albuquerque, NM, Boulder, CO, Davis, CA, Los Angeles, CA, Reno, NV, and Salt Lake City, UT, all connected by video. Participants included scientists and managers. The author team met the following day for their only meeting in person. Subsequently, authors held discussions in regular teleconferences. Many chapter authors met at the all-author meeting March 26–28, 2018, in Bethesda, MD.
' report_identifier: nca4 statement: 'Heat-associated deaths and illnesses, vulnerabilities to chronic disease, and other health risks to people in the Southwest result from increases in extreme heat, poor air quality, and conditions that foster pathogen growth and spread (high confidence). Improving public health systems, community infrastructure, and personal health can reduce serious health risks under future climate change (medium confidence).
' uncertainties: "Uncertainties in the climate and hydrologic drivers of regional changes affecting public health include 1) differences in projections from multiple GCMs and associated uncertainties related to regional downscaling methods, 2) variability in projections of extreme precipitation, 3) uncertainties in summer and fall precipitation projections for the region,{{< tbib '88' 'e8089a19-413e-4bc5-8c4a-7610399e268c' >}} and 4) uncertainties in models that project occurrence and levels of climate-sensitive exposures that are known to impact public health, such as local and regional ozone air pollution, particulate air pollution (for example, increases from wildfire emissions or reductions from advancements in vehicle emissions control technology), or occurrence and exposure to toxins or pathogens.
Studies of non-fatal illnesses using healthcare services data can yield critical insights different from those one can derive from death data. Most studies of heat impacts on health have focused on deaths rather than nonfatal illnesses. This is primarily because hospitalization and emergency department data, compared with death certificate data, are not as available or uniform across locations, and when they are available it can be difficult to access them due to concerns for patient confidentiality. Ongoing enhancements to electronic medical records technology and adoption across the healthcare services sector will potentially address those limitations in the near future and will provide invaluable data resources to identify and adopt prevention strategies that reduce the vulnerability of patients and populations to the adverse effects of climate-sensitive exposures.
More recent work focusing on the more deadly neuroinvasive West Nile virus indicates that regionally, the central and southern parts of the country may experience increasing cost from this vector-borne disease in the future.{{< tbib '178' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}},{{
While improvements to individual health and to clinical and community infrastructure are highly likely to 1) improve physical capacity to adapt to climate effects, 2) diminish the overall impacts on population health, and 3) increase societal capacity to respond quickly to dampen the effects of long-term and emergency responses,{{< tbib '446' '46b92d0e-f9f2-4b12-8b9e-8c27d6a4b9da' >}},{{
There is very high confidence that the arctic sea ice will continue to reduce in size over the next 20–40 years, and it is likely that the Arctic Ocean will be nearly ice-free in late summer by mid-century based on current climate models. There is also high confidence that this melting will have an effect on the northward expansion of North Pacific fish species and associated effects on associated food webs. There is very high confidence that continued melting of the Arctic Ocean ice will have an effect on the habitat and behavior of polar bear and walrus. There is high confidence that Alaska’s ocean waters are becoming increasingly acidic. Given this increase, it is very likely that there will be biological impacts, but it is uncertain which species will be affected and to what extent.
' evidence: "Changes in arctic sea ice and its impacts on marine ecosystems and various biological resources are well documented by 38 years of satellite records{{< tbib '280' '2aa47611-1a24-4796-b0a8-a0ba3092e470' >}} and the scientific literature.{{< tbib '48' '13e01b3b-caf8-4d85-ac0f-5689df47762a' >}},{{
The Alaska regional chapter was developed through public input via workshops and teleconferences and review of relevant literature, primarily post 2012. Formal and informal technical discussions and narrative development were conducted by the chapter lead and contributing authors via email exchanges, teleconferences, webinars, in-person meetings, and public meetings. The authors considered inputs and comments submitted by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The author team also engaged in targeted consultations during multiple exchanges with contributing authors, who provided additional expertise on subsets of the Traceable Account associated with each Key Message.
' report_identifier: nca4 statement: 'Alaska’s marine fish and wildlife habitats, species distributions, and food webs, all of which are important to Alaska’s residents, are increasingly affected by retreating and thinning arctic summer sea ice, increasing temperatures, and ocean acidification. Continued warming will accelerate related ecosystem alterations in ways that are difficult to predict, making adaptation more challenging (very likely, very high confidence).
' uncertainties: 'To date, relatively few of Alaska’s marine species have been studied for their response to ocean acidification, and the assessment of potential impacts is challenging due to each species’ differing habitats, life cycle stages, and response and adaptation mechanisms. It is known that some organisms respond more dramatically to environmental change than others, and warming ocean temperatures may be more significant in the short term than ocean acidification. There is significant uncertainty in the projected increase of shipping through the Arctic and the Bering Strait, since much of this increase will be driven by economic factors and not climate or other environmental change.
' uri: /report/nca4/chapter/alaska/finding/key-message-26-1 url: ~ - chapter_identifier: alaska confidence: 'There is high confidence that wildfire in Alaska will continue but medium confidence as to its ultimate effect on vegetation and permafrost, which is often dependent on fire fields available (e.g., older forests or new growth shrublands), the fire intensity, and the return rate. There is high confidence that the north coast of Alaska is eroding at high rates. It is likely that coastal erosion is accelerating in response to climate change but medium to low confidence as to the location and rate because of limited studies and datasets documenting this. There is high confidence that river erosion will continue but medium confidence as to when, where, and to what extent this will occur across Alaska because of differences in local climatic and geographic qualities of the area in question. There is high confidence and it is likely that the glaciers in Alaska will continue to diminish, especially those that are tidewater glaciers.
' evidence: "Permafrost
Multiple studies of permafrost in Alaska have shown that the gradual warming of the ground{{< tbib '105' '5a612de8-a07d-48c0-a7ca-c4b705157070' >}} has resulted in the warming and thawing of permafrost over the past 30 years,{{< tbib '79' '7fbfdebd-eb73-40be-88ec-109ad7a226fd' >}},{{
Wildfire
It has been well documented that wildfires are a common occurrence in Alaska, especially the interior boreal areas, although they have also occurred in areas of arctic tundra,{{< tbib '114' '9e7065c6-93b9-4bf7-8883-3547a9199ea6' >}},{{
Coastal and River Erosion
The shoreline along Alaska's northern coast has eroded at some of the fastest rates in the Nation, putting local communities, oil fields, and coastal habitat at risk.{{< tbib '19' 'cf15559b-f1e8-4022-945b-45ab149dc1a8' >}} Unlike the contiguous United States, Alaska is subject to glacial and periglacial processes that make permafrost and sea ice key controlling factors of coastal erosion and flooding. Thermal degradation of permafrost leads to enhanced rates of erosion along permafrost-rich coastal shorelines{{< tbib '19' 'cf15559b-f1e8-4022-945b-45ab149dc1a8' >}} and subsidence of already low-lying regions. Longer sea ice-free seasons, higher ground temperatures, and relative sea level rise are expected to exacerbate flooding and accelerate erosion in many regions, leading to the loss of more shoreline in the future.{{< tbib '19' 'cf15559b-f1e8-4022-945b-45ab149dc1a8' >}}
While erosion and changed river courses are a normal part of landscape evolution, lateral river erosion rates are likely to change over time, but the direction and magnitude of these changes are poorly understood. Major river erosion events are typically tied to high hydrological flows or the melting of permafrost along river and stream banks. Statewide, evidence for changes in maximum gauged streamflows is mixed, with a majority of locations having no significant trend.{{< tbib '289' '41ed988f-4fa6-476d-90c9-ef9e3e8d1806' >}} There is significance for seasonal changes in the timing of peak flows in interior Alaska, though increases in the absolute magnitude are not well evident in existing data.{{< tbib '290' '5e61fa98-c1ff-42e6-aa82-10dad90342d9' >}} Riverine erosion is a serious problem for a significant number of communities.{{< tbib '123' '49a37e8f-eef6-4ee6-9705-fac54c48df30' >}} Significant resources have been expended to slow erosion at some communities, often through the construction of berms and bank stabilization projects. These projects have a mixed record of success and nearly always require ongoing maintenance.
Glacier Change
Airborne altimetry surveys of Alaska glaciers spanning the 1994–2013 interval and covering about 40% of the region’s glacierized area{{< tbib '137' 'df531aa2-4a99-4ce7-9dd9-744729e2161d' >}} yield decadal timescale mass balance estimates for individual glaciers and a regional estimate.{{< tbib '291' '08047702-47b0-4401-ab44-a0f46a16efe5' >}} Several new modeling studies suggest that the measured rates of Alaska ice loss are likely to increase in coming decades,{{< tbib '139' 'c426adb7-b055-4726-80f1-82d7846f46c0' >}},{{
Interdisciplinary research along the Gulf of Alaska is providing new insights into the role of glacier runoff in structuring downstream freshwater and nearshore marine ecosystems.{{< tbib '101' '141ed68e-5810-4735-afee-878ceb6041cc' >}} End-of-century projections from physically based models suggest that anticipated atmospheric warming (2°–4.5°C) will drive volume losses of 32%–58% for Alaska glaciers.{{< tbib '142' '226e7316-1460-4cfe-94a1-4bca27549241' >}} Increases in river chemical ions due to glacial runoff and permafrost melt have also been associated with diminishing glaciers in Alaska.{{< tbib '94' '7c14626a-343f-48a3-9076-1bd656f663c3' >}},{{
The Alaska regional chapter was developed through public input via workshops and teleconferences and review of relevant literature, primarily post 2012. Formal and informal technical discussions and narrative development were conducted by the chapter lead and contributing authors via email exchanges, teleconferences, webinars, in-person meetings, and public meetings. The authors considered inputs and comments submitted by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The author team also engaged in targeted consultations during multiple exchanges with contributing authors, who provided additional expertise on subsets of the Traceable Account associated with each Key Message.
' report_identifier: nca4 statement: 'Alaska residents, communities, and their infrastructure continue to be affected by permafrost thaw, coastal and river erosion, increasing wildfire, and glacier melt. These changes are expected to continue into the future with increasing temperatures, which would directly impact how and where many Alaskans will live (very likely, high confidence).
' uncertainties: 'Some events such as wildfires and coastal storms are dependent on regional and local current weather conditions, and the exact landscape or ecosystem response can be highly variable. Future effects are also dependent on quick response actions and adaptation measures.
' uri: /report/nca4/chapter/alaska/finding/key-message-26-2 url: ~ - chapter_identifier: alaska confidence: 'There is high confidence that there will be a continuation of trends causing higher winter temperatures, increased storm events, increased frequency and extent of wildfires, and increased permafrost thawing with associated erosion. Given these trends, there is very likely to be subsequent human health effects, but the distribution and magnitude of these effects remain uncertain.
' evidence: "The evidence base for climate-related health threats can be divided into three main categories. First are those threats that have strong documentation of both the climate or environmental driver and the health effect. An example is the emergence of gastrointestinal illness due to the northward expansion of the bacteria Vibrio parahaemolyticus among Alaska shellfish. Other threats with a similar level of evidence include increased venomous insect stings.
Second, some health threats are based on a combination of well-documented climate-driven environmental changes and records of anecdotal community observations of health impacts. Examples include the increased risk of injury or death from exposure among winter subsistence-related travelers or respiratory problems from smoke inhalation during wildfires. The community observations of these threats point to a real trend.{{< tbib '10' 'cc3776b7-7ea8-42e9-802d-2ef5e6ac2f40' >}},{{
The third category is those threats that are logical inferences of potential health risks based on documented environmental changes and community-vulnerability assessments. Examples include the well-documented threats from coastal storms to community infrastructure and shorelines and the damage to community water and sanitation systems from permafrost thawing or erosion. The risk of physical harm from major storm or flooding events is obvious, and the loss of a water/sewer system would likewise pose a clear threat to health through waterborne or water-washed infections. However, these threats are based on likely outcomes from existing trends in environmental change. The human health effects are either undocumented or are anticipated in the future. Many of the infectious disease risks and harmful algal blooms (HABs) fall into this category; where range expansion of pathogens or vectors is occurring, health effects are likely to follow.
" href: https://data.globalchange.gov/report/nca4/chapter/alaska/finding/key-message-26-3.yaml identifier: key-message-26-3 ordinal: 3 process: 'The Alaska regional chapter was developed through public input via workshops and teleconferences and review of relevant literature, primarily post 2012. Formal and informal technical discussions and narrative development were conducted by the chapter lead and contributing authors via email exchanges, teleconferences, webinars, in-person meetings, and public meetings. The authors considered inputs and comments submitted by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The author team also engaged in targeted consultations during multiple exchanges with contributing authors, who provided additional expertise on subsets of the Traceable Account associated with each Key Message.
' report_identifier: nca4 statement: 'A warming climate brings a wide range of human health threats to Alaskans, including increased injuries, smoke inhalation, damage to vital water and sanitation systems, decreased food and water security, and new infectious diseases (very likely, high confidence). The threats are greatest for rural residents, especially those who face increased risk of storm damage and flooding, loss of vital food sources, disrupted traditional practices, or relocation. Implementing adaptation strategies would reduce the physical, social, and psychological harm likely to occur under a warming climate (very likely, high confidence).
' uncertainties: 'The greatest uncertainties in the health threats of climate change lie in the geographic distribution, magnitude, duration, and capacity to detect the effects. Many of the impacts of climate changes are most evident in rural Alaska, which is an enormous area and sparsely populated. Thus, sporadic events with geographic variability such as storms or HABs may have a range of human health effects from none to severe, depending on the timing and location of exposure. Likewise, the magnitude and duration of the effects on health are difficult to predict based on variability in the source of risk and human adaptation. The lack of repeated outbreaks of V. parahaemolyticus illnesses from raw shellfish consumption is a good example of how adaptations in aquaculture practices and commercial regulations, along with likely changes in consumer practices, appear to have reduced the magnitude of the health threats, compared with initial outbreak. Finally, we have limited capacity to detect many of the health outcomes associated with climate change. The organized reporting and monitoring of climate-linked health effects by public health are limited to the toxin-mediated illnesses, some of the infectious diseases, mortality events, and unusual clusters of illnesses or injuries. Even among those conditions, underreporting of illnesses is common due to healthcare-seeking behavior, lack of recognition by medical providers due to unfamiliarity or limited diagnostic capacities, or incomplete compliance. For many of the anticipated health effects, such as nonoccupational injuries, mental health issues, and respiratory conditions, there may be documentation in a person’s individual health records, but no systems are in place to collect such information and link these illnesses to climate or environmental events or conditions. Large administrative healthcare databases, such as the Alaska Hospital Discharge Data System or the Alaska Health Information Exchange, could be used for focused investigations or ongoing monitoring. However, these would only be useful for severe illnesses with large geographic or multiyear distributions. These datasets would likely miss health events that do not result in emergency room visits or hospitalizations, that are rare, or that occur in irregular episodes. Data from ambulatory clinic visits, community surveys, or syndrome-based surveillance efforts would be needed to detect and characterize uncommon or less severe health occurrences.
' uri: /report/nca4/chapter/alaska/finding/key-message-26-3 url: ~ - chapter_identifier: alaska confidence: 'There is high confidence that climate change is having far-reaching effects on Alaska’s Indigenous peoples. It is likely that most of these impacts will have negative effects, as they undermine existing behaviors, patterns, infrastructure, and expectations. It is also likely that there will continue to be some benefits and opportunities stemming from climate-related changes. There is medium confidence that the negative impacts can be reduced and the new opportunities maximized with appropriate policy and regulatory action, as not all aspects of change can be addressed in this way, and it is unclear whether such a systematic approach is plausible in light of the way programs and policies are administered in Alaska’s Indigenous communities.
' evidence: "Many studies have examined different aspects of Alaska’s Indigenous communities, including the ways climate change is affecting or can affect subsistence,{{< tbib '15' 'e0b0f2a6-5ac8-4196-8634-6123511e0051' >}},{{
The Alaska regional chapter was developed through public input via workshops and teleconferences and review of relevant literature, primarily post 2012. Formal and informal technical discussions and narrative development were conducted by the chapter lead and contributing authors via email exchanges, teleconferences, webinars, in-person meetings, and public meetings. The authors considered inputs and comments submitted by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The author team also engaged in targeted consultations during multiple exchanges with contributing authors, who provided additional expertise on subsets of the Traceable Account associated with each Key Message.
' report_identifier: nca4 statement: 'The subsistence activities, culture, health, and infrastructure of Alaska’s Indigenous peoples and communities are subject to a variety of impacts, many of which are expected to increase in the future (likely, high confidence). Flexible, community-driven adaptation strategies would lessen these impacts by ensuring that climate risks are considered in the full context of the existing sociocultural systems (likely, medium confidence).
' uncertainties: 'There is little question that climate change is having widespread and far-reaching impacts on Alaska’s Indigenous peoples. It is less clear, however, exactly which peoples and communities are responding to the changes they face. One community may be able to seize a new opportunity or may be able to adjust effectively to at least some forms of change, whereas another community will not be able to do either. More needs to be understood about these differences, the reasons for them, and how adaptability and resilience can be fostered.
It is also unclear how, exactly, the changes will influence one another as they occur in the context of all that is happening in Alaska Native life. For example, climate change may mean hunters have to travel farther to hunt. GPS allows for more reliable navigation, and four-stroke engines provide more confidence when traveling farther offshore. At the same time, rising fuel prices mean it is more expensive to travel far, perhaps limiting the ability of a hunter to take advantage of better navigation and motors. How these competing influences will balance out is difficult to say and requires more attention.
' uri: /report/nca4/chapter/alaska/finding/key-message-26-4 url: ~ - chapter_identifier: alaska confidence: 'There is high confidence and it is very likely that future damage to infrastructure from thawing permafrost and coastal erosion will cost hundreds of millions of dollars annually to repair or replace. There is high confidence and it is likely that timely repair and maintenance of infrastructure can reduce damages and avoid some of the added costs. There is medium confidence and it is very likely that these costs will be offset in part by savings from reduced space heating needs.
' evidence: "Coastal erosion affects a number of coastal communities, with the highest rates on the Arctic coastline.{{< tbib '19' 'cf15559b-f1e8-4022-945b-45ab149dc1a8' >}} Coastal erosion and flooding in some cases will require that entire communities, or portions of communities, relocate to safer terrain. The U.S. Army Corps of Engineers identified erosion threats to 31 communities requiring partial or complete relocation.{{< tbib '123' '49a37e8f-eef6-4ee6-9705-fac54c48df30' >}} Relocation costs for seven vulnerable communities identified in a 2009 U.S. Government Accountability Office (GAO) study ranged from $80 to $200 million per community.{{< tbib '122' '1807de04-16a3-422a-a5bc-d241def97f88' >}}
Melting glaciers will increase the role of seasonal precipitation patterns for hydroelectric power generation. River discharge has been increasing during the winter since the 1960s, but because reservoirs are generally full in fall, investments to increase reservoir heights would be required to take advantage of increased fall precipitation.{{< tbib '145' '09961450-e217-4cf4-b11f-fab19c8ea9ed' >}}
National Weather Service (NWS) daily weather summaries show that heating degree days have already declined by 5% in Sitka, 6% in Fairbanks and Nome, and 8% in Anchorage and Utqiaġvik (formally known as Barrow) as compared to mid-20th century levels. The same NWS data show that increased cooling degree days from warmer summer temperatures provide only a small offset to the beneficial effect of lower heating costs.
" href: https://data.globalchange.gov/report/nca4/chapter/alaska/finding/key-message-26-5.yaml identifier: key-message-26-5 ordinal: 5 process: 'The Alaska regional chapter was developed through public input via workshops and teleconferences and review of relevant literature, primarily post 2012. Formal and informal technical discussions and narrative development were conducted by the chapter lead and contributing authors via email exchanges, teleconferences, webinars, in-person meetings, and public meetings. The authors considered inputs and comments submitted by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The author team also engaged in targeted consultations during multiple exchanges with contributing authors, who provided additional expertise on subsets of the Traceable Account associated with each Key Message.
' report_identifier: nca4 statement: 'Climate warming is causing damage to infrastructure that will be costly to repair or replace, especially in remote Alaska (very likely, high confidence). It is also reducing heating costs throughout the state (likely, medium confidence). These effects are very likely to grow with continued warming (very likely, high confidence). Timely repair and maintenance of infrastructure can reduce the damages and avoid some of these added costs (likely, high confidence).
' uncertainties: 'The extent, rate, and patterns of coastal erosion at locations other than along the north coast, and including deltas and rivers, are poorly known. Change in the patterns and trends of erosion (for example, an increase in the rate associated with warming and climate change), is expected but poorly documented for most locations due to the scarcity of historical data.
Future energy prices are highly uncertain, generating a high level of uncertainty around the dollar value of the savings in space heating costs associated with the projected decline in heating degree days.
Wildfire suppression costs depend on future policy decisions for wildfire management. Property damage from wildfire depends on uncertain future settlement and development patterns.
' uri: /report/nca4/chapter/alaska/finding/key-message-26-5 url: ~ - chapter_identifier: alaska confidence: 'There is high confidence that proactive adaptation can reduce costs, generate social and economic opportunity, and improve livelihood security. It is likely and there is high confidence that proactive adaptation will be affected by external factors, such as global markets that are beyond the control of the organization or institution implementing the adaptations.
It is likely and there is very high confidence that direct engagement and partnership with communities will be a critical element of adaptation success, as this has strong evidence and high consensus in the literature; however, there are a limited number of publications that document this partnership model in Alaska.
' evidence: "Research investigating costs of adapting to projected climate changes in Alaska in the realms of public infrastructure and wildfire suppression indicates cost savings from adaptation.{{< tbib '21' 'b7e764c8-8912-4d18-8dd3-1555ab8da1c2' >}},{{
Adaptation actions to the impacts of climate change in Alaska have been transitioning from awareness and concern to education and actions.{{< tbib '135' 'b8ad073b-11cd-4b02-809d-f992e02566b4' >}},{{
Most research reports on case studies and actions that describe transparent, collaborative, and accessible information though data sharing, building of networks, and long-term partnerships with communities.{{< tbib '252' '46337d79-86c4-4e77-bab9-724c5f44c63f' >}},{{
A number of climate adaptation guidebooks focus on Alaska and Canada, which have related adaptation challenges.{{< tbib '134' 'f3fa0761-8412-46f5-9da4-b9b467bd8521' >}} Universities, governments, and nongovernmental organizations produced these guidebooks for a range of audiences, including rural Alaska Native communities, local governments, and state governments. Key phases in the adaptation planning process that are consistent across the majority of the guidebooks include building partnerships and networks of stakeholders; conducting vulnerability and risk assessments; establishing priorities, options, and an implementation plan and evaluation metrics; implementing the preferred option; and conducting ongoing monitoring and adjustment of activities.{{< tbib '134' 'f3fa0761-8412-46f5-9da4-b9b467bd8521' >}} Guidebooks specific to Alaska Natives and Canadian Inuit and First Nations peoples emphasize the importance of community support and participation in the adaptation planning process.{{< tbib '134' 'f3fa0761-8412-46f5-9da4-b9b467bd8521' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/alaska/finding/key-message-26-6.yaml identifier: key-message-26-6 ordinal: 6 process: 'The Alaska regional chapter was developed through public input via workshops and teleconferences and review of relevant literature, primarily post 2012. Formal and informal technical discussions and narrative development were conducted by the chapter lead and contributing authors via email exchanges, teleconferences, webinars, in-person meetings, and public meetings. The authors considered inputs and comments submitted by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The author team also engaged in targeted consultations during multiple exchanges with contributing authors, who provided additional expertise on subsets of the Traceable Account associated with each Key Message.
' report_identifier: nca4 statement: 'Proactive adaptation in Alaska would reduce both short- and long-term costs associated with climate change, generate social and economic opportunity, and improve livelihood security (likely, high confidence). Direct engagement and partnership with communities is a vital element of adaptation in Alaska (likely, very high confidence).
' uncertainties: "Little research has been conducted to track and evaluate the efficacy of implementation of existing adaptation planning in Alaska or to assess the possibilities for maladaptation. Similarly, the feedbacks and synergies are not well documented between adaptation and changes in physical, natural, and social systems. More research is needed to understand cross-sector and cumulative impacts and how they can best be addressed in an all-inclusive manner.{{< tbib '135' 'b8ad073b-11cd-4b02-809d-f992e02566b4' >}}
" uri: /report/nca4/chapter/alaska/finding/key-message-26-6 url: ~ - chapter_identifier: hawaii-and-pacific-islands confidence: 'There is very high confidence in further increases in temperature in the region, based on the consistent results of global climate models showing continued significant increases in temperature in the Hawai‘i–USAPI region for all plausible emissions scenarios.
There is low confidence regarding projected changes in precipitation patterns, stemming from the divergent results of global models and downscaling approaches and from uncertainties around future emissions. However, for leeward areas of Hawai‘i and the eastern part of the Federated States of Micronesia (FSM), future decreases in precipitation are somewhat more likely, based on greater agreement between downscaling approaches for Hawai‘i and greater agreement among global models for eastern FSM.
There is very high confidence in future increases in sea level, based on widely accepted evidence that warming will increase global sea level, with amplified effects in the low latitudes.
There is medium confidence in the increasing risk of both drought and flood extremes patterns, based on both observed changes (for example, increasing lengths of wet and dry periods) and projected effects of warming on extreme weather globally.
There is medium confidence in possible future catastrophic impacts on food and water security resulting from saltwater contamination in low atolls due to sea level rise; this is based on very high confidence in continuing sea level rise, the known effects of saltwater contamination on water supply and agriculture, and uncertainty regarding the effectiveness of adaptation measures.
' evidence: "Vulnerability of water supplies to climate change: With their isolation and limited land areas, Hawai‘i and the USAPI are vulnerable to the effects of climate change on water supplies.{{< tbib '72' '97ae6e5b-3482-4760-a4f4-9e00ee6337b6' >}},{{
Temperature change: In Hawai‘i, air temperature increased by 0.76°F (0.42°C) over the past 100 years. The year 2015 was the warmest on record at 1.43°F (0.79°C) above the 100-year average. Mean and minimum (nighttime) temperatures both show long-term, statistically significant increasing trends, while the diurnal temperature range (the average difference between daily minimum and maximum temperature) shows a long-term, statistically significant decreasing trend.{{< tbib '59' '7621e6f5-4234-4a44-bb1d-8278429deb2b' >}} Estimates of historical temperature changes in Hawai‘i are based on the relatively few observing stations with long records and represent the best available data. Further temperature increases in the Hawai‘i–USAPI region are highly likely. Northern tropical Pacific (including Micronesia) sea level air temperatures are expected to increase by 2.2°–2.7°F (1.2°–1.5°C) by mid-century and by 2.7°–5.9°F (1.5°–3.3°C) by 2100.{{< tbib '63' '1fca63fb-3033-445e-99ba-1136da451058' >}} Southern tropical Pacific (including American Sāmoa) sea level air temperatures are expected to increase by 1.8°–3.1°F (1.0°–1.7°C) by mid-century and by 2.5°–5.8°F (1.4°–3.2°C) by 2100.{{< tbib '63' '1fca63fb-3033-445e-99ba-1136da451058' >}} Increasing temperatures throughout the Hawai‘i–USAPI region might cause increases in potential evapotranspiration,{{< tbib '226' 'bdbb00c1-6c40-4e03-9120-2df759b580a7' >}} with consequent negative impacts on water supplies.
Precipitation change: While Hawai‘i precipitation has experienced upward and downward changes across a range of timescales, more than 90% of the state had a net downward rainfall trend during 1920–2012.{{< tbib '60' 'e6d1098e-93cc-4285-9d16-6e52c5e302f7' >}} Projections of future precipitation changes in Hawai‘i are still uncertain. Using a dynamical downscaling approach to project climate changes in Hawai‘i for the 20-year period at the end of the this century under a middle-of-the-road scenario (SRES A1B) resulted in increases in mean annual rainfall of up to 30% in the wet windward areas of Hawaiʻi and Maui Islands and decreases of 40% in some of the dry leeward and high-elevation interior areas.{{< tbib '34' 'f60beed2-efd0-40c8-8f94-b81d3e9f1509' >}} Somewhat different results were obtained using an independent statistical downscaling method.{{< tbib '34' 'f60beed2-efd0-40c8-8f94-b81d3e9f1509' >}} For the lower scenario (RCP4.5), mean annual rainfall in Hawai‘i is projected by statistical downscaling to have only small changes in windward areas of Hawai‘i and Maui Islands, to decrease by 10%–20% in windward areas of the other islands, and to decrease by up to 60% in leeward areas for the period 2041–2070. For the same scenario, the late-century (2071–2100) projection is similar to the 2041–2070 projection, except that a larger portion of the leeward areas will experience reductions of 20%–60%. For the higher scenario (RCP8.5), windward areas of Hawai‘i and Maui Islands will see changes between +10% and −10%, and rainfall in leeward areas will decrease by 10% to more than 60% by the 2041–2070 period. By the late-century period (2071–2100), windward areas of Hawai‘i and Maui Islands will see increases of up to 20%, windward areas on other islands will have decreases of 10% to 30%, and leeward areas will have decreases of 10% to more than 60%. The number of climate and water resources monitoring stations has declined across the region,{{< tbib '23' '7350d7b3-6e95-4375-ba23-26756b441fc2' >}},{{
Trends in hydrological extremes in Hawai‘i: Increasing trends in extreme 30-day rainfall and the lengths of consecutive dry-day and consecutive wet-day periods{{< tbib '66' 'f8ccfb79-1bed-462d-9172-c56a71b542b9' >}} indicate that Hawai‘i’s rainfall is becoming more extreme and suggest that both droughts and floods are becoming more frequent in Hawai‘i. With the addition of more years of observed data, and a more detailed spatiotemporal analysis from a grid-box level down to the island level, this contrasts with the earlier findings of a decreasing trend in the number of extreme rainfall events in Hawai‘i.{{< tbib '227' '39d80273-7b1f-4342-8c9d-439e262dea4f' >}}
Saltwater contamination due to sea level rise: Sea level rise exacerbates the existing vulnerability of groundwater lenses on small coral islands to contamination by saltwater intrusion by amplifying the impacts of freshwater lens-shrinking droughts and storm-related overwash events.{{< tbib '69' 'dc90f15e-2420-461e-ba38-f65717485591' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/hawaii-and-pacific-islands/finding/key-message-27-1.yaml identifier: key-message-27-1 ordinal: 1 process: "To frame this chapter, the regional leads wanted to maximize inclusiveness and represent the key sectoral interests of communities and researchers. To select sectors and a full author team, the coordinating lead author and regional chapter lead author distributed an online Google survey from September to October 2016. The survey received 136 responses representing Hawaiʻi and all the U.S.-Affiliated Pacific Islands (USAPI) jurisdictions; respondents identified which of the National Climate Assessment (NCA) sectors they were most interested in learning about with respect to climate change in the Pacific Islands and suggested representative case studies.{{< tbib '223' '884675c9-3e31-483d-b6b9-fd53b99875ae' >}} The five top sectors were picked as the focus of the chapter, and a total of eight lead authors with expertise in those sectors were invited to join the regional team. To solicit additional participation from potential technical contributors across the region, two informational webinars spanning convenient time zones across the Pacific were held; 35 people joined in. The webinars outlined the NCA history and process, as well as past regional reports and ways to participate in this Fourth National Climate Assessment (NCA4).
A critical part of outlining the chapter and gathering literature published since the Third National Climate Assessment (NCA3){{< tbib '224' 'dd5b893d-4462-4bb3-9205-67b532919566' >}} was done by inviting technical experts in the key sectors to participate in a half-day workshop led by each of the lead authors. A larger workshop centered on adaptation best practices was convened with participants from all sectors, as well as regional decision-makers. In all, 75 participants, including some virtual attendees, took part in the sectoral workshops on March 6 and 13, 2017. Finally, to include public concerns and interests, two town hall discussion events on March 6 and April 19, 2017, were held in Honolulu, Hawaiʻi, and Tumon, Guam, respectively. Approximately 100 participants attended the town halls. Throughout the refining of the Key Messages and narrative sections, authors met weekly both via conference calls and in person to discuss the chapter and carefully review evidence and findings. Technical contributors were given multiple opportunities to respond to and edit sections. The process was coordinated by the regional chapter lead and coordinating lead authors, as well as the Pacific Islands sustained assessment specialist.
" report_identifier: nca4 statement: 'Dependable and safe water supplies for Pacific island communities and ecosystems are threatened by rising temperatures (very high confidence), changing rainfall patterns (low confidence), sea level rise (very high confidence), and increased risk of extreme drought and flooding (medium confidence). Islands are already experiencing saltwater contamination due to sea level rise, which is expected to catastrophically impact food and water security, especially on low-lying atolls (medium confidence). Resilience to future threats relies on active monitoring and management of watersheds and freshwater systems.
' uncertainties: "Effects of warming on evapotranspiration: There are uncertainties in how warming will affect cloud cover, solar radiation, humidity, and wind speed. All of these affect potential evapotranspiration and changes in soil moisture, and the effects will differ by region.{{< tbib '228' '44466960-d3a9-4374-b1cf-893bb8a476f0' >}}
Future precipitation changes: Global models differ in their projections of precipitation changes for the Hawai‘i–USAPI region.{{< tbib '63' '1fca63fb-3033-445e-99ba-1136da451058' >}} For Hawai‘i, downscaled projections differ according to the choice of global model time horizon, emissions scenario, and downscaling method.{{< tbib '229' '9171ec97-c44b-48eb-80b3-2756ba8a14a3' >}}
" uri: /report/nca4/chapter/hawaii-and-pacific-islands/finding/key-message-27-1 url: ~ - chapter_identifier: hawaii-and-pacific-islands confidence: 'It is very likely that air and water temperatures will increase and that sea level will rise (very high confidence). Research indicates that global mean sea level rise will exceed previous estimates and that, in the USAPI, sea level rise is likely to be higher than the global mean (likely, high confidence). As a result, it is likely that climate change will affect low-lying and coastal ecosystems in Hawaiʻi and other Pacific islands, with medium confidence in forecasts of the effects on these ecosystems.
There is low confidence as to how rainfall patterns will shift across the main Hawaiian Islands. It is considered likely that changes in rainfall will result in ecologic shifts expected to threaten some species. However, there is low confidence in specific ecologic forecasts because the direction and magnitude of rainfall changes are uncertain, and there is a lack of robust understanding of how species will respond to those changes. It seems as likely as not that the responses of terrestrial biomes and species to climate change will result in additional complexity in the management of rare and threatened species.
' evidence: "Projections of sea level rise have been made at both regional and local scales (see Traceable Account for Key Message 3). Based on these projections, the effects of sea level rise on coastal ecosystems have been evaluated for the Northwest Hawaiian Islands.{{< tbib '18' '8fd88741-58fd-4753-ae35-af3a2ed38915' >}},{{
Forecasts of how climate change will affect rainfall and temperature in the main Hawaiian Islands have been based on both statistical and dynamical downscaling of global climate models (GCMs; see Traceable Account for Key Message 1). Statewide vulnerability models have been developed for nearly all species of native plants{{< tbib '233' 'c0eb08ae-6725-4e68-b99e-1f2cef382c25' >}} and forest birds,{{< tbib '43' 'f483b8cf-8401-40ec-9001-23466261d5fa' >}} showing substantial changes in the available habitat for many species. More detailed modeling within Hawaiʻi Volcanoes National Park has suggested that rare and listed plants being managed in Special Ecological Areas will experience climate changes that make the habitat in these areas unsuitable.{{< tbib '91' '5eac12ba-e664-4eb2-aa66-18d9067566d8' >}}
Effects of climate change on streamflow in Hawaiʻi will largely be driven by changes in rainfall, although geologic conditions affect the discharge of groundwater that provides base flow during dry weather.{{< tbib '234' '381cc925-f22b-46a5-8a36-3e99bbd52635' >}} A regional watershed model from the windward side of Hawaiʻi Island suggested that control of an invasive tree with high water demand would somewhat mitigate decreases in streamflow that might be caused by a drier climate.{{< tbib '44' 'e69ceccd-2c27-48f0-b3fe-46ce1b67f636' >}} Finally, it has been suggested that ocean acidification will decrease the viability of the planktonic larvae of native Hawaiian stream fishes.{{< tbib '99' '0c523a5a-213e-491a-9dcf-0a2c7eb05d77' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/hawaii-and-pacific-islands/finding/key-message-27-2.yaml identifier: key-message-27-2 ordinal: 2 process: "To frame this chapter, the regional leads wanted to maximize inclusiveness and represent the key sectoral interests of communities and researchers. To select sectors and a full author team, the coordinating lead author and regional chapter lead author distributed an online Google survey from September to October 2016. The survey received 136 responses representing Hawaiʻi and all the U.S.-Affiliated Pacific Islands (USAPI) jurisdictions; respondents identified which of the National Climate Assessment (NCA) sectors they were most interested in learning about with respect to climate change in the Pacific Islands and suggested representative case studies.{{< tbib '223' '884675c9-3e31-483d-b6b9-fd53b99875ae' >}} The five top sectors were picked as the focus of the chapter, and a total of eight lead authors with expertise in those sectors were invited to join the regional team. To solicit additional participation from potential technical contributors across the region, two informational webinars spanning convenient time zones across the Pacific were held; 35 people joined in. The webinars outlined the NCA history and process, as well as past regional reports and ways to participate in this Fourth National Climate Assessment (NCA4).
A critical part of outlining the chapter and gathering literature published since the Third National Climate Assessment (NCA3){{< tbib '224' 'dd5b893d-4462-4bb3-9205-67b532919566' >}} was done by inviting technical experts in the key sectors to participate in a half-day workshop led by each of the lead authors. A larger workshop centered on adaptation best practices was convened with participants from all sectors, as well as regional decision-makers. In all, 75 participants, including some virtual attendees, took part in the sectoral workshops on March 6 and 13, 2017. Finally, to include public concerns and interests, two town hall discussion events on March 6 and April 19, 2017, were held in Honolulu, Hawaiʻi, and Tumon, Guam, respectively. Approximately 100 participants attended the town halls. Throughout the refining of the Key Messages and narrative sections, authors met weekly both via conference calls and in person to discuss the chapter and carefully review evidence and findings. Technical contributors were given multiple opportunities to respond to and edit sections. The process was coordinated by the regional chapter lead and coordinating lead authors, as well as the Pacific Islands sustained assessment specialist.
" report_identifier: nca4 statement: 'Pacific island ecosystems are notable for the high percentage of species found only in the region, and their biodiversity is both an important cultural resource for island people and a source of economic revenue through tourism (very high confidence). Terrestrial habitats and the goods and services they provide are threatened by rising temperatures (very likely, very high confidence), changes in rainfall (likely, medium confidence), increased storminess (likely, medium confidence), and land-use change (very likely, very high confidence). These changes promote the spread of invasive species (likely, low confidence) and reduce the ability of habitats to support protected species and sustain human communities (likely, medium confidence). Some species are expected to become extinct (likely, medium confidence) and others to decline to the point of requiring protection and costly management (likely, high confidence).
' uncertainties: 'The timing and magnitude of sea level rise are somewhat uncertain. There is greater uncertainty on how climate change will affect the complex patterns of precipitation over the high islands of Hawaiʻi. There is also high uncertainty about how plants will respond to changes in their habitats and the extent to which climate change will foster the spread of invasive species.
' uri: /report/nca4/chapter/hawaii-and-pacific-islands/finding/key-message-27-2 url: ~ - chapter_identifier: hawaii-and-pacific-islands confidence: 'There is very high confidence that a continued rise in global temperature will lead to increases in the rate of sea level rise. There is less confidence in the projected amounts of sea level rise during this century, and there is low confidence in the upper bounds of sea level rise by the end of the century. Sea level rise will very likely lead to saltwater intrusion, coastal erosion, and wave flooding. It is very likely this will strain the sustainability of human infrastructure systems, limit freshwater resources, and challenge food availability. If the high-end projections of future sea level rise materialize, it is very likely this will threaten the very existence of Pacific island coastal communities.
' evidence: "Multiple lines of research have shown that changes in melting in Greenland,{{< tbib '110' 'ef6eb8d0-6301-4987-a2ff-9606e1f4177a' >}} the Antarctic,{{< tbib '107' 'ae82c8a3-3033-4103-91e9-926a27d1fa18' >}} and among alpine glaciers,{{< tbib '111' '5d34229c-b521-42f4-aad1-f2ffc600879d' >}} as well as the warming of the ocean,{{< tbib '113' '6bbe13d9-4992-456c-b97d-42947994b6be' >}} have occurred faster than expected. The rate of sea level rise is accelerating,{{< tbib '103' 'd7ed19d6-e5ac-4b44-b686-0a8a16fc431b' >}} and the early signs of impact are widely documented.{{< tbib '9' '7717dd13-7f6b-4b7c-ab84-571d50f7b8da' >}} Relative to the year 2000, global mean sea level (GMSL) is very likely to rise 0.3–0.6 feet (9–18 cm) by 2030, 0.5–1.2 feet (15–38 cm) by 2050, and 1.0–4.3 feet (30–130 cm) by 2100 (very high confidence in lower bounds; medium confidence in upper bounds for 2030 and 2050; low confidence in upper bounds for 2100).{{< tbib '17' 'c66bf5a9-a6d7-4043-ad99-db0ae6ae562c' >}},{{
Changes in precipitation,{{< tbib '235' 'c57f7893-035e-49d9-b31d-83856dab8624' >}} Pacific sea level,{{< tbib '4' '6e320831-727b-482d-982a-45732be3790f' >}} climate variability,{{< tbib '3' 'e5f02380-28e9-4238-994f-09a2efba32ae' >}} and the unsustainable practices of many human communities among Pacific islands{{< tbib '127' 'f22f00d3-1456-4fef-b286-a4af1494bb93' >}} all converge to increase the vulnerability of coastal populations{{< tbib '135' 'e16534d0-638a-4fdc-88fb-426611965c54' >}} as climate change continues in the future.{{< tbib '55' 'a9307aae-3eb6-41f2-9921-ba96fa8ac075' >}} As sea level rises and average atmospheric temperature continues to increase, wave events{{< tbib '37' '1b9a155a-3d54-41ff-a844-1400bb326927' >}} associated with changing weather patterns{{< tbib '140' 'fc838fdf-81d0-488b-a2b5-0781d7bbc9ef' >}} constitute a growing mechanism for delivering{{< tbib '12' 'f4859f1b-a4d7-4e21-a05b-70204fd6df59' >}} damaging saltwater into island aquifer systems,{{< tbib '13' '88dcd306-5ae7-48df-8411-658f9c5d97bc' >}} ecosystems,{{< tbib '129' 'd055c0df-2c85-4ee1-a3c6-8e6c79e425bd' >}} and human infrastructure systems.{{< tbib '17' 'c66bf5a9-a6d7-4043-ad99-db0ae6ae562c' >}}
In Hawaiʻi, studies by the Hawaiʻi Climate Change Mitigation and Adaptation Commission{{< tbib '42' '0244c888-89df-4a3c-a7f1-79af0a0a6f00' >}} reveal that with 3.2 feet of sea level rise, over 25,800 acres of land in the state would be rendered unusable. Some of that land would erode into the ocean, some would become submerged by inches or feet of standing water, and some areas would be dry most of the year but repeatedly washed over by seasonal high waves. Statewide, about 34% of that potentially lost land is designated for urban use, 25% is designated for agricultural use, and 40% is designated for conservation. The loss of urban land is expected to increase pressure on the development of inland areas, including those designated as agricultural and conservation lands. Across the state, over 6,500 structures located near the shoreline would be compromised or lost with 3.2 feet of sea level rise. Some of these vulnerable structures include houses and apartment buildings, and their loss would result in over 20,000 displaced residents in need of new homes. The value of projected flooded structures, combined with the land value of the 25,800 acres projected to be flooded, amounts to over $19 billion across the state (in 2013 dollars; $19.6 billion in 2015 dollars). However, this figure does not encompass the full loss potential in the state, as monetary losses that would occur from the chronic flooding of roads, utilities, and other public infrastructure were not analyzed in this report and are expected to amount to as much as an order of magnitude greater than the potential economic losses from land and structures. For example, over 38 miles of major roads would be chronically flooded across the state with 3.2 feet of sea level rise. Utilities, such as water, wastewater, and electrical systems, often run parallel and underneath roadways, making lost road mileage a good indication of the extent of lost utilities. This chronic flooding of infrastructure would have significant impacts on local communities as well as reverberating effects around each island.
The loss of valuable natural and cultural resources across all islands would cost the state dearly, due to their intrinsic value. Beaches that provide for recreation, wildlife habitat, and cultural tradition would erode, from iconic sites such as Sunset Beach on O‘ahu to neighborhood beach access points rarely visited by anyone except local residents. Some beaches would be lost entirely if their landward migration is blocked by roads, structures, shoreline armoring, or geology. The flooding of the more than 2,000 on-site sewage disposal systems with 3.2 feet of sea level rise would result in diminished water quality in streams and at beaches and shoreline recreation areas. The loss of and harm to native species and entire ecosystems would have implications for Hawaiian cultural traditions and practices, which are closely tied to the natural environment. Further, nearly 550 cultural sites in the state would be flooded, and many Hawaiian Home Lands communities would be impacted by flooding. In some cases, inland migration or careful relocation of these natural and cultural resources is expected to be possible. In other cases, the resources are inextricably bound to place and would be permanently altered by flooding.{{< tbib '42' '0244c888-89df-4a3c-a7f1-79af0a0a6f00' >}}
Marra and Kruk (2017){{< tbib '142' 'a4512dba-212b-4139-b4bd-7dcdc5632f03' >}} describe climate trends for the USAPI. Globally and locally, observations of GHG concentrations, surface air temperatures, sea level, sea surface temperature, and ocean acidification show rising trends at an increasing rate. Trends in measures of rainfall, surface winds, and tropical cyclones are not as readily apparent. Patterns of climate variability characterize these measures and tend to mask long-term trends. A lack of high-quality, long-term observational records, particularly with respect to in situ stations, contributes to difficulties in discerning trends. To maintain and enhance our ability to assess environmental change, attention needs to be given to robust and sustained monitoring.
There are consistent subregional changes in the number of days with high winds. The global frequency of tropical cyclones (TCs) appears to be showing a slow downward trend since the early 1970s. In the Pacific region, long-term TC trends in frequency and intensity are relatively flat, with the record punctuated by as many active as inactive years.{{< tbib '142' 'a4512dba-212b-4139-b4bd-7dcdc5632f03' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/hawaii-and-pacific-islands/finding/key-message-27-3.yaml identifier: key-message-27-3 ordinal: 3 process: "To frame this chapter, the regional leads wanted to maximize inclusiveness and represent the key sectoral interests of communities and researchers. To select sectors and a full author team, the coordinating lead author and regional chapter lead author distributed an online Google survey from September to October 2016. The survey received 136 responses representing Hawaiʻi and all the U.S.-Affiliated Pacific Islands (USAPI) jurisdictions; respondents identified which of the National Climate Assessment (NCA) sectors they were most interested in learning about with respect to climate change in the Pacific Islands and suggested representative case studies.{{< tbib '223' '884675c9-3e31-483d-b6b9-fd53b99875ae' >}} The five top sectors were picked as the focus of the chapter, and a total of eight lead authors with expertise in those sectors were invited to join the regional team. To solicit additional participation from potential technical contributors across the region, two informational webinars spanning convenient time zones across the Pacific were held; 35 people joined in. The webinars outlined the NCA history and process, as well as past regional reports and ways to participate in this Fourth National Climate Assessment (NCA4).
A critical part of outlining the chapter and gathering literature published since the Third National Climate Assessment (NCA3){{< tbib '224' 'dd5b893d-4462-4bb3-9205-67b532919566' >}} was done by inviting technical experts in the key sectors to participate in a half-day workshop led by each of the lead authors. A larger workshop centered on adaptation best practices was convened with participants from all sectors, as well as regional decision-makers. In all, 75 participants, including some virtual attendees, took part in the sectoral workshops on March 6 and 13, 2017. Finally, to include public concerns and interests, two town hall discussion events on March 6 and April 19, 2017, were held in Honolulu, Hawaiʻi, and Tumon, Guam, respectively. Approximately 100 participants attended the town halls. Throughout the refining of the Key Messages and narrative sections, authors met weekly both via conference calls and in person to discuss the chapter and carefully review evidence and findings. Technical contributors were given multiple opportunities to respond to and edit sections. The process was coordinated by the regional chapter lead and coordinating lead authors, as well as the Pacific Islands sustained assessment specialist.
" report_identifier: nca4 statement: 'The majority of Pacific island communities are confined to a narrow band of land within a few feet of sea level. Sea level rise is now beginning to threaten critical assets such as ecosystems, cultural sites and practices, economics, housing and energy, transportation, and other forms of infrastructure (very likely, very high confidence). By 2100, increases of 1–4 feet in global sea level are very likely, with even higher levels than the global average in the U.S.-Affiliated Pacific Islands (very likely, high confidence). This would threaten the food and freshwater supply of Pacific island populations and jeopardize their continued sustainability and resilience (likely, high confidence). As sea level rise is projected to accelerate strongly after mid-century, adaptation strategies that are implemented sooner can better prepare communities and infrastructure for the most severe impacts.
' uncertainties: 'Major uncertainties lie in understanding and projecting the future melting behavior of the Antarctic and Greenland ice sheets. To date, new observations attest to melting occurring at higher than expected rates. If this continues to be the case, it is plausible for future sea level rise to exceed even worst-case scenarios. Secondary feedbacks to warming, such as changes in the global thermohaline circulation; shifts in major weather elements, such as the intertropical convergence zone and the polar jet stream; and unexpected modes of heat distribution across the hemispheres risk complex responses in the climate system that are not well understood. Pacific climate variability is a governing element that amplifies many aspects of climate change, such as drought, sea level, storminess, and ocean warming. A number of mechanisms through which climate change might alter Pacific variability have been proposed on the basis of physical modeling, but our understanding of the variability remains low, and confidence in projected changes is also low. For instance, in any given Pacific region, our understanding of future TC occurrence, intensity, and frequency is low. Future physical responses to climate change that have not yet been described are possible. These uncertainties greatly limit our ability to identify the chronology of changes to expect in the future.
' uri: /report/nca4/chapter/hawaii-and-pacific-islands/finding/key-message-27-3 url: ~ - chapter_identifier: hawaii-and-pacific-islands confidence: 'There is high confidence that fisheries and the livelihoods they support are threatened by warmer ocean temperatures and ocean acidification. Widespread and multiyear coral reef bleaching and mortality are already occurring. It is likely, based on modeled SST projections, that by mid-century, bleaching will occur annually with associated mortality.
There is medium confidence in the projection of annual bleaching by mid-century, as it does not take into account any adaptation in corals.
There is high confidence that bleaching and rising seawater acidity will result in loss of reef structure, leading to lower fisheries yields and loss of coastal protection. This is deemed very likely because significant coral mortality has recently been observed in western Hawaiian coral reefs that suffered from the 2015 bleaching event. Further, the positive relationship between fish density and coral reef cover is well established. The magnitude of this impact depends on the extent that coral species exhibit adaptive or resilience capacity.
There is medium confidence that declines in oceanic fishery productivity of up to 15% and 50% are likely by mid-century and 2100, respectively. These declines are considered likely because we have seen related linkages between climate variability such as ENSO and the Pacific Decadal Oscillation and fisheries yields that provide an analog in some ways to global warming impacts. The uncertainty lies in our limited understanding of the linkages and feedbacks in the very complex oceanic food web. As temperate habitats warm, they will likely gain some tropical species, while the tropical habitats will likely only lose species.
' evidence: "The Key Message was developed based on input from an expert working group convened at the outset of this section development and supported by extensive literature.
Ocean warming: NCA3 documented historical increases in sea surface temperature (SST), and current levels in much of the region have now exceeded the upper range of background natural variation.{{< tbib '32' '081bdbe7-f95f-4708-b18c-e7bc797effa7' >}},{{
Ocean acidification: Atmospheric carbon dioxide levels recorded at Mauna Loa, Hawaiʻi, have recently exceeded 400 parts per million, and oceanic pH levels measured off Oʻahu have steadily declined from an annual average of about 8.11 to 8.07 over the past 25 years (data from Hawaiʻi Ocean Time Series, SOEST, University of Hawaiʻi) and are projected to decrease to 7.8 by 2100.{{< tbib '123' 'fa5d3ea3-a0ad-4418-b516-20c748528b2f' >}} As pH declines, it lowers the saturation level of aragonite (the form of calcium carbonate used by corals and many other marine organisms), reducing coral and shell growth.{{< tbib '125' '7ab1d9e1-75a1-48c5-8d85-02258496f919' >}} By the end of the century, aragonite saturation is projected to decline from a current level of 3.9 to 2.4, representing extremely marginal conditions for coral reef growth.{{< tbib '32' '081bdbe7-f95f-4708-b18c-e7bc797effa7' >}},{{
Bleaching events: These continue to occur—most recently over successive years—with widespread impacts.{{< tbib '45' 'be538e70-7c97-4680-a580-7ee398361090' >}},{{
Mortality: During the 2014–2015 bleaching events, coral mortality in western Hawaiʻi was estimated at 50%{{< tbib '45' 'be538e70-7c97-4680-a580-7ee398361090' >}} and over 90% at the pristine equatorial Jarvis Atoll.{{< tbib '156' '71443a23-b42f-4435-93ac-78d32df5bd30' >}}
Coral reef ecosystem impacts: Coral reef cover around the Pacific Islands region is projected to decline from the current average level of about 40% to 15%–30% by 2035 and 10%–20% by 2050.{{< tbib '123' 'fa5d3ea3-a0ad-4418-b516-20c748528b2f' >}} The loss of coral reef habitat is projected to reduce fish abundance and fisheries yields by 20%.{{< tbib '123' 'fa5d3ea3-a0ad-4418-b516-20c748528b2f' >}} Loss of coral reefs will result in increased coastal erosion.{{< tbib '23' '7350d7b3-6e95-4375-ba23-26756b441fc2' >}},{{
Insular fisheries: Insular fishes, including both coral reef fishes and more mobile, coastal pelagics (species such as mahi mahi and wahoo), are impacted both from declines in carrying capacity and loss from migration in response to temperature change. Taken together, declines in maximum catch potential exceeding 50% from late 20th century levels under the higher scenario are projected by 2100 for the exclusive economic zones of most islands in the central and western Pacific.{{< tbib '163' 'faaa3555-cab7-44a6-a71e-dc269d1b67ce' >}}
Oceanic fisheries: A number of studies have projected that ocean warming will result in lower primary productivity due to increased vertical stratification and loss of biodiversity as organisms move poleward.{{< tbib '129' 'd055c0df-2c85-4ee1-a3c6-8e6c79e425bd' >}},{{
To frame this chapter, the regional leads wanted to maximize inclusiveness and represent the key sectoral interests of communities and researchers. To select sectors and a full author team, the coordinating lead author and regional chapter lead author distributed an online Google survey from September to October 2016. The survey received 136 responses representing Hawaiʻi and all the U.S.-Affiliated Pacific Islands (USAPI) jurisdictions; respondents identified which of the National Climate Assessment (NCA) sectors they were most interested in learning about with respect to climate change in the Pacific Islands and suggested representative case studies.{{< tbib '223' '884675c9-3e31-483d-b6b9-fd53b99875ae' >}} The five top sectors were picked as the focus of the chapter, and a total of eight lead authors with expertise in those sectors were invited to join the regional team. To solicit additional participation from potential technical contributors across the region, two informational webinars spanning convenient time zones across the Pacific were held; 35 people joined in. The webinars outlined the NCA history and process, as well as past regional reports and ways to participate in this Fourth National Climate Assessment (NCA4).
A critical part of outlining the chapter and gathering literature published since the Third National Climate Assessment (NCA3){{< tbib '224' 'dd5b893d-4462-4bb3-9205-67b532919566' >}} was done by inviting technical experts in the key sectors to participate in a half-day workshop led by each of the lead authors. A larger workshop centered on adaptation best practices was convened with participants from all sectors, as well as regional decision-makers. In all, 75 participants, including some virtual attendees, took part in the sectoral workshops on March 6 and 13, 2017. Finally, to include public concerns and interests, two town hall discussion events on March 6 and April 19, 2017, were held in Honolulu, Hawaiʻi, and Tumon, Guam, respectively. Approximately 100 participants attended the town halls. Throughout the refining of the Key Messages and narrative sections, authors met weekly both via conference calls and in person to discuss the chapter and carefully review evidence and findings. Technical contributors were given multiple opportunities to respond to and edit sections. The process was coordinated by the regional chapter lead and coordinating lead authors, as well as the Pacific Islands sustained assessment specialist.
" report_identifier: nca4 statement: 'Fisheries, coral reefs, and the livelihoods they support are threatened by higher ocean temperatures and ocean acidification (very likely, high confidence).Widespread coral reef bleaching and mortality have been occurring more frequently, and by mid-century these events are projected to occur annually, especially if current trends in emissions continue (likely, medium confidence). Bleaching and acidification will result in loss of reef structure, leading to lower fisheries yields, and loss of coastal protection and habitat (very likely, very high confidence). Declines in oceanic fishery productivity of up to 15% and 50% of current levels are projected by mid-century and 2100, respectively, under the higher scenario (RCP8.5; likely, medium confidence).
' uncertainties: "A major uncertainty for coral reefs is whether they can evolve rapidly enough to keep up with the changing temperature and pH.{{< tbib '164' '06b7a4b5-9c7e-42de-8dee-c54d443a2af3' >}},{{
There is high confidence that climate change is having far-reaching effects on the land security, livelihood security, habitat security, and cultural food security of Indigenous peoples of the Pacific.
It is likely that most of these impacts will have negative effects on the cultural heritage of the Pacific island communities.
There is high confidence that traditional knowledge together with science will support the adaptive capacity of Pacific island communities to survive on their islands.
' evidence: "The research supporting this Key Message examines the impacts of climate change on the lands, territories, and resources of the Pacific region and its Indigenous communities.
It is foundational to highlight the interconnectedness and important familial relationship Indigenous peoples have with their lands, territories, and resources. Native Hawaiian attorneys and professors Sproat and Akutagawa discuss the health impacts and threats that climate change poses for Indigenous communities and their relationship with ancestral resources. Sproat states that “any such loss will result in the loss of culture.”{{< tbib '177' '9c017401-c8d2-4d9f-9d69-4a7bb247594b' >}} Further support is found in a community health assessment done by Akutagawa and others that states, “In traditional Hawaiian conceptions of health, personal harmony and well-being are deemed to stem from one’s relationship with the land, sea, and spiritual world”.{{< tbib '176' '85e07f9f-b899-4b21-8028-3a9c2d85d792' >}}
Governments and their support institutions are also sharing outcomes of projects they’ve initiated over the years that document not only the successes but also the challenges, observations, and lessons learned.{{< tbib '149' '567b51b3-07f8-4e75-81d5-76b394218947' >}},{{
In writing this Key Message, the authors considered the body of research focusing on the impacts of climate change on Pacific communities such as sea level rise,{{< tbib '104' 'b36fdfcb-d735-4cad-a0df-806725e7d8f4' >}},{{
There is very strong evidence that traditional knowledge is key to the resilience and adaptive capacity of Indigenous peoples of the Pacific.{{< tbib '21' '5db43854-3226-408c-a5ef-aa7898146f1f' >}},{{
To frame this chapter, the regional leads wanted to maximize inclusiveness and represent the key sectoral interests of communities and researchers. To select sectors and a full author team, the coordinating lead author and regional chapter lead author distributed an online Google survey from September to October 2016. The survey received 136 responses representing Hawaiʻi and all the U.S.-Affiliated Pacific Islands (USAPI) jurisdictions; respondents identified which of the National Climate Assessment (NCA) sectors they were most interested in learning about with respect to climate change in the Pacific Islands and suggested representative case studies.{{< tbib '223' '884675c9-3e31-483d-b6b9-fd53b99875ae' >}} The five top sectors were picked as the focus of the chapter, and a total of eight lead authors with expertise in those sectors were invited to join the regional team. To solicit additional participation from potential technical contributors across the region, two informational webinars spanning convenient time zones across the Pacific were held; 35 people joined in. The webinars outlined the NCA history and process, as well as past regional reports and ways to participate in this Fourth National Climate Assessment (NCA4).
A critical part of outlining the chapter and gathering literature published since the Third National Climate Assessment (NCA3){{< tbib '224' 'dd5b893d-4462-4bb3-9205-67b532919566' >}} was done by inviting technical experts in the key sectors to participate in a half-day workshop led by each of the lead authors. A larger workshop centered on adaptation best practices was convened with participants from all sectors, as well as regional decision-makers. In all, 75 participants, including some virtual attendees, took part in the sectoral workshops on March 6 and 13, 2017. Finally, to include public concerns and interests, two town hall discussion events on March 6 and April 19, 2017, were held in Honolulu, Hawaiʻi, and Tumon, Guam, respectively. Approximately 100 participants attended the town halls. Throughout the refining of the Key Messages and narrative sections, authors met weekly both via conference call and in person to discuss the chapter and carefully review evidence and findings. Technical contributors were given multiple opportunities to respond to and edit sections. The process was coordinated by the regional chapter lead and coordinating lead authors, as well as the Pacific Islands sustained assessment specialist.
" report_identifier: nca4 statement: 'Indigenous peoples of the Pacific are threatened by rising sea levels, diminishing future freshwater availability, and shifting ecosystem services. These changes imperil communities’ health, well-being, and modern livelihoods, as well as their familial relationships with lands, territories, and resources (likely, high confidence). Built on observations of climatic changes over time, the transmission and protection of traditional knowledge and practices, especially via the central role played by Indigenous women, are intergenerational, place-based, localized, and vital for ongoing adaptation and survival.
' uncertainties: 'There is no doubt that Indigenous communities of the Pacific are being impacted by climate change. However, the rate and degree of the impacts on the spiritual, relational, and ancestral connectedness varies from community to community and on the type of practice being impacted. This variable is difficult to document and express in certain circumstances. Additionally, the degree of the impact varies according to the livelihoods of the community and the specific climatic and socioeconomic and political circumstances of the island in question.
' uri: /report/nca4/chapter/hawaii-and-pacific-islands/finding/key-message-27-5 url: ~ - chapter_identifier: hawaii-and-pacific-islands confidence: 'There is medium confidence that climate change will yield compounding economic, environmental, social, and cultural costs. There is greater evidence of these compounding costs resulting from extreme events that are exacerbated by climate change.
There is high confidence that food and water insecurity will result in severe disruptions to livelihoods, including the displacement and relocation of island communities.
It is likely that the absence of interventions will result in the costly and lengthy rebuilding of communities and livelihoods and more displacement and relocation. Events have played out repeatedly across the region and have resulted in damage, disruptions, and displacements.
' evidence: "For Atlantic and eastern North Pacific hurricanes and western North Pacific typhoons, increases are projected in precipitation rates and intensity. The frequency of the most intense of these storms is projected to increase in the western North Pacific and in the eastern North Pacific (see also Key Message 3).{{< tbib '246' '52ce1b63-1b04-4728-9f1b-daee39af665e' >}} Studies indicate that Hawaiʻi will see an increased frequency of tropical cyclones (TCs) due to storm tracks shifting northward in the central North Pacific.{{< tbib '40' '9082a92d-e1be-4346-8657-7b172a8f91bc' >}},{{
The Climate Science Special Report (CSSR) summarizes extensive evidence that is documented in the climate science literature and is similar to statements made in NCA3 and international{{< tbib '106' 'f03117be-ccfe-4f88-b70a-ffd4351b8190' >}} assessments.{{< tbib '33' '75cf1c0b-cc62-4ca4-96a7-082afdfe2ab1' >}} More recent downscaling studies have further supported these assessments,{{< tbib '248' '4f1e7aa1-0c36-4220-ac77-7d55bcb33061' >}} though pointing out that the changes (future increased intensity and TC precipitation rates) will not necessarily occur in all basins.{{< tbib '246' '52ce1b63-1b04-4728-9f1b-daee39af665e' >}}
Damage from TCs is significant. Tropical Cyclone Evan struck Sāmoa in December 2012 and caused damage and losses of approximately $210 million dollars (dollar year not reported), representing 30% of its annual gross domestic product (GDP). Tropical Cyclone Pam struck Vanuatu, Tuvalu, and Kiribati in 2015; in Vanuatu, it killed 11 people and caused approximately $450 million (dollar year not reported) in damages and losses, equal to 64% of GDP.{{< tbib '196' '08f6548b-e879-45a6-97df-3790e804e73e' >}}
In the CSSR, future relative sea level rise as shown for the 3.3-feet (1 m) Interagency scenario in 2100 indicates that, because they are far from all glaciers and ice sheets, relative sea level rise in Hawai‘i and other Pacific islands due to any source of melting land ice is amplified by the static-equilibrium effects. Static-equilibrium effects on sea level are produced by the gravitational, elastic, and rotational effects of mass redistribution resulting from ice loss.{{< tbib '105' '3bae2310-7572-47e2-99a4-9e4276764934' >}}
Sea level rise across Hawaiʻi is projected to rise another 1–3 feet by the end of this century. Sea level rise has caused an increase in high tide floods associated with nuisance-level impacts. High tide floods are events in which water levels exceed the local threshold (set by the National Oceanic and Atmospheric Administration’s National Weather Service) for minor impacts. These events can damage infrastructure, cause road closures, and overwhelm storm drains. Along the Hawaiian coastline, the number of tidal flood days (all days exceeding the nuisance-level threshold) has also increased, with the greatest number occurring in 2002–2003. Continued sea level rise will present major challenges to Hawaiʻi’s coastline through coastal inundation and erosion. Seventy percent of Hawaiʻi’s beaches have already been eroded over the past century, with more than 13 miles of beach completely lost. Sea level rise will also affect Hawai‘i’s coastal storm water and wastewater management systems and is expected to cause extensive economic impacts through ecosystem damage and losses in property, tourism, and agriculture.{{< tbib '247' '2eff8dd3-b0da-474d-b7be-ba223baa8396' >}}
In the Pacific Islands region, population, urban centers, and critical infrastructure are concentrated along the coasts. This results in significant damages during inundation events. In December 2008, wind waves generated by extratropical cyclones, exacerbated by sea level rise, caused a series of inundation events in five Pacific island nations.{{< tbib '9' '7717dd13-7f6b-4b7c-ab84-571d50f7b8da' >}} An area of approximately 3,000 km in diameter was affected, impacting approximately 100,000 people. Across the islands, major infrastructure damage and crop destruction resulted, costing millions of dollars and impacting livelihoods, food security, and freshwater resources.
The increases in the frequency and intensity of climate change hazards, including cyclones, wind, rainfall, and flooding, pose an immediate danger to the Pacific Islands region. A decrease in the return times of extreme events, which will reduce the ability of systems to recover, will likely cause long-term declines in welfare.{{< tbib '181' 'dd36c0e3-b849-46c9-8685-dd76a465223a' >}} For small islands states, the damage costs of sea level rise are large in relation to the size of their economies.{{< tbib '194' '2e8e659c-1150-4516-b2c2-fd3176f9c641' >}},{{
The social science research on climate and conflict suggests a possible association between climate variability and change and conflict. Consensus or conclusive evidence of a causal link remains elusive. Hsiang et al. (2013){{< tbib '249' '6013994a-8717-4a99-935a-8a13800fcdc5' >}} find strong causal evidence linking climatic events to human conflict across a range of spatial scales and time periods and across all major regions of the world. They further demonstrate that the magnitude of climate influence is substantial.{{< tbib '249' '6013994a-8717-4a99-935a-8a13800fcdc5' >}} Specifically, large deviations from average precipitation and mild temperatures systematically increase the risk of many types of conflict (intergroup to interpersonal), often substantially. Hsiang and Burke (2014){{< tbib '250' 'e3a15302-b1ec-4bfe-9ac3-3a2cf23d3303' >}} describe their detailed meta-analysis, examining 50 rigorous quantitative studies, and find consistent support for a causal association between climatological changes and various conflict outcomes.{{< tbib '250' 'e3a15302-b1ec-4bfe-9ac3-3a2cf23d3303' >}} They note, however, that multiple mechanisms can explain this association and that the literature is currently unable to decisively exclude any proposed pathway between climatic change and human conflict.{{< tbib '249' '6013994a-8717-4a99-935a-8a13800fcdc5' >}}
Evidence of the impact of climate on livelihoods is also well established. Barnett and Adger (2003, 2007){{< tbib '191' '0dc9b00c-1fc7-43ee-bcb6-4c8e783e88f1' >}},{{
To frame this chapter, the regional leads wanted to maximize inclusiveness and represent the key sectoral interests of communities and researchers. To select sectors and a full author team, the coordinating lead author and regional chapter lead author distributed an online Google survey from September to October 2016. The survey received 136 responses representing Hawaiʻi and all the U.S.-Affiliated Pacific Islands (USAPI) jurisdictions; respondents identified which of the National Climate Assessment (NCA) sectors they were most interested in learning about with respect to climate change in the Pacific Islands and suggested representative case studies.{{< tbib '223' '884675c9-3e31-483d-b6b9-fd53b99875ae' >}} The five top sectors were picked as the focus of the chapter, and a total of eight lead authors with expertise in those sectors were invited to join the regional team. To solicit additional participation from potential technical contributors across the region, two informational webinars spanning convenient time zones across the Pacific were held; 35 people joined in. The webinars outlined the NCA history and process, as well as past regional reports and ways to participate in this Fourth National Climate Assessment (NCA4).
A critical part of outlining the chapter and gathering literature published since the Third National Climate Assessment (NCA3){{< tbib '224' 'dd5b893d-4462-4bb3-9205-67b532919566' >}} was done by inviting technical experts in the key sectors to participate in a half-day workshop led by each of the lead authors. A larger workshop centered on adaptation best practices was convened with participants from all sectors, as well as regional decision-makers. In all, 75 participants, including some virtual attendees, took part in the sectoral workshops on March 6 and 13, 2017. Finally, to include public concerns and interests, two town hall discussion events on March 6 and April 19, 2017, were held in Honolulu, Hawaiʻi, and Tumon, Guam, respectively. Approximately 100 participants attended the town halls. Throughout the refining of the Key Messages and narrative sections, authors met weekly both via conference call and in person to discuss the chapter and carefully review evidence and findings. Technical contributors were given multiple opportunities to respond to and edit sections. The process was coordinated by the regional chapter lead and coordinating lead authors, as well as the Pacific Islands sustained assessment specialist.
" report_identifier: nca4 statement: 'Climate change impacts in the Pacific Islands are expected to amplify existing risks and lead to compounding economic, environmental, social, and cultural costs (likely, medium confidence). In some locations, climate change impacts on ecological and social systems are projected to result in severe disruptions to livelihoods (likely, high confidence) that increase the risk of human conflict or compel the need for migration. Early interventions, already occurring in some places across the region, can prevent costly and lengthy rebuilding of communities and livelihoods and minimize displacement and relocation (likely, high confidence).
' uncertainties: "A key uncertainty remains the lack of a supporting, detectable anthropogenic signal in the historical data to add further confidence to some regional projections. As such, confidence in the projections is based on agreement among different modeling studies. Additional uncertainty stems from uncertainty in both the projected pattern and magnitude of future sea surface temperatures.{{< tbib '33' '75cf1c0b-cc62-4ca4-96a7-082afdfe2ab1' >}},{{
One study projects an increase in tropical cyclone frequency (TCF) of occurrence around the Hawaiian Islands but stipulates that TCF around the Hawaiian Islands is still very low in a warmed climate, so that a quantitative evaluation of the future change involves significant uncertainties.{{< tbib '40' '9082a92d-e1be-4346-8657-7b172a8f91bc' >}}
Uncertainties in reconstructed global mean sea level (GMSL) change relate to the sparsity of tide gauge records, particularly before the middle of the twentieth century, and to the use of a variety of statistical approaches to estimate GMSL change from these sparse records. Uncertainties in reconstructed GMSL change before the 20th century also relate to the lack of geological proxies (preserved physical characteristics of the past environment that can stand in for direct measurement) for sea level change, the interpretation of these proxies, and the dating of these proxies. Uncertainty in attribution relates to the reconstruction of past changes and the magnitude of natural variability in the climate.
Since NCA3, multiple approaches have been used to generate probabilistic projections of GMSL rise. These approaches are in general agreement. However, emerging results indicate that marine portions of the Antarctic ice sheet are more unstable than previously thought. The rate of ice sheet mass changes remains challenging to project.
In sea level rise projections, Antarctic contributions are amplified along U.S. coastlines, while Greenland contributions are dampened; regional sea level is projected to be higher than if driven by a more extreme Greenland contribution and a somewhat less extreme Antarctic contribution.{{< tbib '17' 'c66bf5a9-a6d7-4043-ad99-db0ae6ae562c' >}}
The degree to which climate variability and change impact conflict, and related causal pathways, remains uncertain. This is compounded by the fact that different types of conflict—social, political, civil, or violent—are conflated.{{< tbib '209' '657d9028-d5b7-4e0c-980e-dd71138c8bd7' >}},{{
Gemenne et al. (2014){{< tbib '208' '32ad430a-4769-4e16-8ece-c28d123504b0' >}} also note that the relationship between climate change and security comes from observation of past patterns and that present and projected climate change have no historical precedent. In effect, understanding past crises and adaptation strategies will no longer be able to help us understand future crises in a time of significant climate change.
The degree to which climate variability and change affect migration decisions made today also remains uncertain. This is in part due to the diverse scenarios that comprise climate migration, which themselves result from multiple drivers of migration.{{< tbib '251' 'b3626f1d-9cfa-469a-b52d-dce3c6a0dff0' >}} Burrows and Kinney (2016){{< tbib '251' 'b3626f1d-9cfa-469a-b52d-dce3c6a0dff0' >}} detail examples of climate extremes leading to migration conflicts since 2000, yet they note that there are surprisingly few case studies on recent climate extremes that lead to migration and conflict specifically, despite an increasing body of literature on the theory.
While researchers disagree as to the degree to which climate change drives conflict and migration and the causal pathways that connect them, there is agreement that further research is needed. Buhaug (2015){{< tbib '252' '9d9049c5-28b9-4029-a6b7-a18838dcdc69' >}} and Gemenne et al. (2014){{< tbib '208' '32ad430a-4769-4e16-8ece-c28d123504b0' >}} argue for research to develop a more refined theoretical understanding of possible indirect and conditional causal connections between climate change and, specifically, violent conflict.{{< tbib '252' '9d9049c5-28b9-4029-a6b7-a18838dcdc69' >}} Hsiang and Burke (2014){{< tbib '250' 'e3a15302-b1ec-4bfe-9ac3-3a2cf23d3303' >}} would like additional research that reduces the number of competing hypotheses that attempt to explain the overwhelming evidence that climatic variables are one of many important causal factors in human conflict.{{< tbib '250' 'e3a15302-b1ec-4bfe-9ac3-3a2cf23d3303' >}} Burrows and Kinney (2016){{< tbib '251' 'b3626f1d-9cfa-469a-b52d-dce3c6a0dff0' >}} explore the potential pathways linking climate change, migration, and increased risk of conflict and argue that future research should focus on other pathways by which climate variability and change are related to conflict, in addition to the climate–migration–conflict pathway. Kallis and Zografos (2014){{< tbib '209' '657d9028-d5b7-4e0c-980e-dd71138c8bd7' >}} seek greater understanding of the potential harm of certain climate change adaptation measures that have the potential to result in maladaptation by spurring conflict.
" uri: /report/nca4/chapter/hawaii-and-pacific-islands/finding/key-message-27-6 url: ~ - chapter_identifier: near-term-adaptation-needs-and-increased-resiliency confidence: 'There is high confidence that the amount of adaptation activity, in particular implementation activity, is increasing. There is less agreement and evidence regarding the consequences of this activity.
' evidence: "There exists extensive documentation in the gray literature of specific adaptation planning and implementation activities underway by local, state, regional, and federal agencies and jurisdictions. The literature also contains reports that attempt to provide an overview of these activities, such as the recent set of case studies in Vogel et. al. (2017).{{< tbib '14' '3c3cc09b-c2d7-4c52-bf8f-c064efa78e93' >}} Websites, such as those of the Georgetown Climate Center (http://www.georgetownclimate.org), provide summaries and examples of adaptation activities in the United States. The sectoral and regional chapters in this National Climate Assessment also provide numerous examples of adaptation planning and implementation activities. The literature also offers work that aims to provide surveys of large numbers of adaptation activity, such as Moser et. al. (2018){{< tbib '121' 'b47b4130-ce3f-4e3e-914d-443a5652abbb' >}} and Stults and Woodruff (2016).{{< tbib '164' '44dd3160-74d0-4173-8ca4-b503fcd93615' >}}
" href: https://data.globalchange.gov/report/nca4/chapter/near-term-adaptation-needs-and-increased-resiliency/finding/key-message-28-1.yaml identifier: key-message-28-1 ordinal: 1 process: 'The scope for this chapter was determined by the Fourth National Climate Assessment (NCA4) Federal Steering Committee, which is made up of representatives from the U.S. Global Change Research Program member agencies. The scope was also informed by research needs identified in the Third National Climate Assessment (NCA3). Authors for this NCA4 chapter were selected to represent a range of public- and private-sector perspectives and experiences relevant to adaptation planning and implementation.
This chapter was developed through technical discussions of relevant evidence and expert deliberation by chapter authors during teleconferences, e-mail exchanges, and a day-long in-person meeting. These discussions were informed by a comprehensive literature review of the evidence base for the current state of adaptation in the United States. The author team obtained input from outside experts in several important areas to supplement its expertise.
' report_identifier: nca4 statement: 'Adaptation planning and implementation activities are occurring across the United States in the public, private, and nonprofit sectors. Since the Third National Climate Assessment, implementation has increased but is not yet commonplace. (High Confidence)
' uncertainties: "While the amount of adaptation-related activity is clearly increasing, the lack of clear standards and the diverse lexicon used in different sectors make it difficult to systematically compare different adaptation activities at the level of outcomes across sectors and regions of the country. In addition, publicly available adaptation plans may never actually result in implementation. It is thus difficult to provide a quantitative assessment of the increase in adaptation activity other than just counting plans and initiatives. Given the reliance on small-sample surveys, judgments about the distribution of adaptation actions across categories have potentially large errors that are difficult to estimate. In addition, it is difficult to assess the contribution of these activities to concrete outcomes such as risk reduction or current and future improvements to well-being, security, and environmental protection.{{< tbib '130' 'dbb9cf98-a2e1-4392-b1f9-38d00259ecdf' >}} There also exists little gap analysis that compares any given set of adaptation activities with what might be appropriate according to some normative standard or what might be reasonably achieved. Thus, while adaptation activities are clearly increasing in the United States, scant evidence exists for judging their consequences.
" uri: /report/nca4/chapter/near-term-adaptation-needs-and-increased-resiliency/finding/key-message-28-1 url: ~ - chapter_identifier: near-term-adaptation-needs-and-increased-resiliency confidence: "There is high confidence that most organizations’ planning is currently based on extensions from the record of local climate conditions.{{< tbib '169' '60233f20-d45f-4086-ada7-00dbd47712c3' >}}
" evidence: "The assumption that the historical record of events and variability will be the same in the future is called the stationarity assumption{{< tbib '27' 'c52f2539-9c5e-4ead-b8b7-f1884c5d662e' >}} and has guided planning for climate and weather events in most places for most of recorded history. The evidence is strong that the stationarity assumption is no longer valid for all impacts and variability in all locations, because climate change is altering both the events and their variability.{{< tbib '3' '666daffe-2c3b-4e2d-9157-16b989860618' >}},{{
The scope for this chapter was determined by the Fourth National Climate Assessment (NCA4) Federal Steering Committee, which is made up of representatives from the U.S. Global Change Research Program member agencies. The scope was also informed by research needs identified in the Third National Climate Assessment (NCA3). Authors for this NCA4 chapter were selected to represent a range of public- and private-sector perspectives and experiences relevant to adaptation planning and implementation.
This chapter was developed through technical discussions of relevant evidence and expert deliberation by chapter authors during teleconferences, e-mail exchanges, and a day-long in-person meeting. These discussions were informed by a comprehensive literature review of the evidence base for the current state of adaptation in the United States. The author team obtained input from outside experts in several important areas to supplement its expertise.
' report_identifier: nca4 statement: 'Successful adaptation has been hindered by the assumption that climate conditions are and will be similar to those in the past. Incorporating information on current and future climate conditions into design guidelines, standards, policies, and practices would reduce risk and adverse impacts. (High Confidence)
' uncertainties: "While significant uncertainties can exist in estimating the extent to which current variability differs from historic observations in any particular location, there is robust evidence that such differences do occur in many locations (see Ch. 18: Northeast; Ch. 19: Southeast; Ch. 20: U.S. Caribbean; Ch. 21: Midwest; Ch. 22: N. Great Plains; Ch. 23: S. Great Plains; Ch. 24: Northwest; Ch. 25: Southwest; Ch. 26: Alaska; and Ch. 27: Hawaiʻi & Pacific Islands).{{< tbib '5' '29960c69-6168-4fb0-9af0-d50bdd91acd3' >}},{{
Significant agreement and strong evidence provide high confidence that adaptation is a form of iterative risk management and that this is an appropriate framework for understanding, addressing, and communicating climate-related risks.{{< tbib '33' '7f8b90be-c5d1-43b5-8b7f-a485ef08c7ec' >}}
" evidence: "Evidence from a large body of literature and observations of experience support the judgment that iterative risk management is a useful framework (e.g., National Research Council 2009, America's Climate Choices 2010, Kunreuther et al. 2012{{< tbib '142' '7ab8b14a-38c7-4128-b0e3-fe1ab65edac0' >}},{{
The scope for this chapter was determined by the Fourth National Climate Assessment (NCA4) Federal Steering Committee, which is made up of representatives from the U.S. Global Change Research Program member agencies. The scope was also informed by research needs identified in the Third National Climate Assessment (NCA3). Authors for this NCA4 chapter were selected to represent a range of public- and private-sector perspectives and experiences relevant to adaptation planning and implementation.
This chapter was developed through technical discussions of relevant evidence and expert deliberation by chapter authors during teleconferences, e-mail exchanges, and a day-long in-person meeting. These discussions were informed by a comprehensive literature review of the evidence base for the current state of adaptation in the United States. The author team obtained input from outside experts in several important areas to supplement its expertise.
' report_identifier: nca4 statement: 'Adaptation entails a continuing risk management process; it does not have an end point. With this approach, individuals and organizations of all types assess risks and vulnerabilities from climate and other drivers of change (such as economic, environmental, and societal), take actions to reduce those risks, and learn over time. (High Confidence)
' uncertainties: 'The literature and practice of climate change are undergoing a process of maturation and convergence. The process began with many organizations and sectors developing their own approaches and terminology in response to climate risks, meaning that a wide variety of approaches still exist in the field. We believe that the field will progress and converge on the most effective approaches, including iterative risk management. But this convergence is still in process, and the outcome remains uncertain.
' uri: /report/nca4/chapter/near-term-adaptation-needs-and-increased-resiliency/finding/key-message-28-3 url: ~ - chapter_identifier: near-term-adaptation-needs-and-increased-resiliency confidence: 'There is suggestive evidence that provides medium confidence that many proactive adaptation actions offer significant benefits that exceed their costs. However, because of a small sample size and insufficient evaluation, it is in general hard to know the extent to which this is true in any particular case. There is strong agreement that evaluating adaptation involves consideration of a wide range of measures of social well-being.
' evidence: "Both limited field applications and literature reviews highlight adaptation co-benefits, including those associated with equity considerations.{{< tbib '83' '971185c1-a31f-4c15-8454-57f273b4ed33' >}} Near-term benefits are assessed from observations of adaptation results, as well as from comparisons to similar situations without such responses; longer-term benefits are generally assessed from projections.
" href: https://data.globalchange.gov/report/nca4/chapter/near-term-adaptation-needs-and-increased-resiliency/finding/key-message-28-4.yaml identifier: key-message-28-4 ordinal: 4 process: 'The scope for this chapter was determined by the Fourth National Climate Assessment (NCA4) Federal Steering Committee, which is made up of representatives from the U.S. Global Change Research Program member agencies. The scope was also informed by research needs identified in the Third National Climate Assessment (NCA3). Authors for this NCA4 chapter were selected to represent a range of public- and private-sector perspectives and experiences relevant to adaptation planning and implementation.
This chapter was developed through technical discussions of relevant evidence and expert deliberation by chapter authors during teleconferences, e-mail exchanges, and a day-long in-person meeting. These discussions were informed by a comprehensive literature review of the evidence base for the current state of adaptation in the United States. The author team obtained input from outside experts in several important areas to supplement its expertise.
' report_identifier: nca4 statement: 'Proactive adaptation initiatives—including changes to policies, business operations, capital investments, and other steps—yield benefits in excess of their costs in the near term, as well as over the long term (medium confidence). Evaluating adaptation strategies involves consideration of equity, justice, cultural heritage, the environment, health, and national security (high confidence).
' uncertainties: 'Benefits are based on understanding the relevant systems so that one can compare similar cases and construct counterfactuals. Such understanding is excellent for many engineered systems (for example, how a storm drain performs under various rainfall scenarios) but is less robust for many biological systems. Benefit–cost ratios can have large uncertainties associated with estimates of costs, the projection of benefits, and the economic valuation of benefits. In addition, because expected differences in benefit–cost ratios are sufficiently large and the number of current examples is sufficiently low, there are large uncertainties in applying results from one case to another.
' uri: /report/nca4/chapter/near-term-adaptation-needs-and-increased-resiliency/finding/key-message-28-4 url: ~ - chapter_identifier: near-term-adaptation-needs-and-increased-resiliency confidence: 'There is significant agreement that provides high confidence, in at least some cases, that both 1) mainstreaming climate information into existing risk management and 2) creating enabling environments and institutions to improve adaptation capacity, implementation, and evaluation reduce risk, produce co-benefits across communities and sectors, and help secure economic investments into the future.
' evidence: "There is significant agreement, but only case study evidence, that effective adaptation can be realized by mainstreaming.{{< tbib '100' '40cd1072-ac17-4dfa-ba98-a554bf1a0458' >}},{{
The scope for this chapter was determined by the Fourth National Climate Assessment (NCA4) Federal Steering Committee, which is made up of representatives from the U.S. Global Change Research Program member agencies. The scope was also informed by research needs identified in the Third National Climate Assessment (NCA3). Authors for this NCA4 chapter were selected to represent a range of public- and private-sector perspectives and experiences relevant to adaptation planning and implementation.
This chapter was developed through technical discussions of relevant evidence and expert deliberation by chapter authors during teleconferences, e-mail exchanges, and a day-long in-person meeting. These discussions were informed by a comprehensive literature review of the evidence base for the current state of adaptation in the United States. The author team obtained input from outside experts in several important areas to supplement its expertise.
' report_identifier: nca4 statement: 'Integrating climate considerations into existing organizational and sectoral policies and practices provides adaptation benefits. Further reduction of the risks from climate change can be achieved by new approaches that create conditions for altering regulatory and policy environments, cultural and community resources, economic and financial systems, technology applications, and ecosystems. (High Confidence)
' uncertainties: 'It is not well understood how community acceptance of needed adaptations develops. This presents both a barrier to the implementation of adaptation measures and an opportunity for additional research into ways to close this gap in understanding. Additionally, a need exists to clarify the co-benefits of addressing multiple threats and opportunities. Effective adaptation also depends on networks of collaboration among researchers and practitioners and the long-term support of monitoring networks. The sustainability of both types of networks is a major uncertainty. Their effectiveness is both an uncertainty and major research need.
' uri: /report/nca4/chapter/near-term-adaptation-needs-and-increased-resiliency/finding/key-message-28-5 url: ~