finding 24.3 : key-message-24-3

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).

This finding is from chapter 24 of Impacts, Risks, and Adaptation in the United States: The Fourth National Climate Assessment, Volume II.

Process for developing key messages:

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 elsewhere07aed96a-e0e8-47dd-81d3-cdff5a6e261c,0b30f1ab-e4c4-4837-aa8b-0e19faccdb94,75cf1c0b-cc62-4ca4-96a7-082afdfe2ab1,f03117be-ccfe-4f88-b70a-ffd4351b8190 and are not included in this chapter. Instead, this chapter focuses on the impact of those projections on the natural resources sector that supports livelihoods (agriculture, forestry, fisheries, and outdoor recreation industry), the intangible values provided by the natural environment (wildlife, habitat, tribal cultures and well-being, and outdoor recreation experiences), human support systems (built infrastructure and health), and frontline communities (farmworkers, tribes, and economically disadvantaged urban communities). The literature cited in this chapter is largely specific to the Northwest states: Washington, Oregon, and Idaho. In addition, the authors selected a series of case studies that highlight specific impacts, challenges, adaptation strategies and successes, and collaborations that are bringing communities together to build climate resilience. The most significant case study is the 2015 case study (Box 24.7), which cuts across all five Key Messages and highlights how extreme climate variability that is happening now may become more normal in the future, providing important insights that can help inform and prioritize adaptation efforts.

Description of evidence base:

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.2ca19a87-6e16-41d2-8767-19767e5a74d1,b7b33c40-58c1-4a5d-a6fa-f850a96d0981,40ffbbdf-74f1-4511-b1f1-a2b2a165185e,a2470cdb-4b8f-4ed6-8c5f-38cd301053a2,eb5903e2-ed98-4136-a6e0-e210b8d9942b,9ea687e5-ed84-4936-9f66-f3bd84b95c09,37c7ffec-3a37-4278-942a-a1ede603934d,97acd205-7e76-4b8d-ae0b-3e2909e8d350,f8aed6de-599d-48ce-a347-f627fdb6fe29,a40ab7ff-2034-4de7-a6c5-07c8696d6412,c37fa7a6-d308-4877-b431-e35bc3763277 Several investigations have highlighted the vulnerability of water supply, hydropower, and transportation to such changes.f640a815-8228-433e-9866-de40710be36d,b7b33c40-58c1-4a5d-a6fa-f850a96d0981,bd3dbfa7-8dc4-4442-9cf2-14f583dc4a36,2de42597-d1db-4d2c-92d7-42441d80e2e5,23c5fab3-02cc-47fe-84b9-0f4c4bd334c2,f61fc3c4-faf7-407b-9199-c4c986cfa01b,666d3c9f-58de-4ec3-bc12-1a8158c7fbad

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.3dd8a56b-03bf-40b4-8b09-6d202e75e901,00c8f221-d78e-40bd-a8f3-e28410d1248c,2b150d72-d285-4d4f-a6d3-2921f72ae3b2 Several studies describe the ways that agencies tasked with water, energy, and transportation management are exploring climate change impacts and potential adaptation options.2bd77a92-b832-4ea3-a6c1-ceba4df79c59,00c8f221-d78e-40bd-a8f3-e28410d1248c,c54bb72b-a4af-41f4-9f0a-1464f047610d,aedd0adb-12af-4f73-81a0-15d9bc7eac55,f6780c98-9a1e-43e4-aacb-d4c67c56c51f,edd7aaf2-c29d-4cd3-bfee-da8b1a9d649c,bcf8435d-1174-4b33-9413-46b31f26b1d1,37e24902-baa5-4fc7-b809-d581695349a8,de25fdf8-90e0-4cbe-be19-80400b583b09,86476666-dabb-45c2-ad49-79484041d1a0

New information and remaining 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.

Assessment of confidence based on evidence:

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.e450ba2c-db69-43c8-8af4-e0c8ce7c8f2f,a2135da9-c8b1-486f-9656-59d8a52b1975,b7b33c40-58c1-4a5d-a6fa-f850a96d0981 These changes are anticipated to raise the risk of flooding, landslides, drought, wildfire, and heat waves. There is medium confidence about the role of redundancy in determining vulnerability. Although this link has been exhibited in many case studies, quantitative evidence at the local and regional scale has yet to be developed.

Impacts discussed in this chapter (e.g., WSDOT 2014, ODOT and OHA 2016, Withycomb 2017, US Climate Resilience Toolkit 2017ce288ad6-4610-400a-805b-fc5e59d20c32,25eb3e40-bc31-4ae8-9555-0b57f455eadd,a8924330-5aa1-4d19-a182-2f4bd380ceda,ed2a0cc7-8ff7-4808-8baa-83fb81cc915d), within other chapters (see Ch. 11: Urban; Ch. 12: Transportation; Ch. 17: Complex Systems; Ch. 28: Adaptation), and elsewhereb7b33c40-58c1-4a5d-a6fa-f850a96d0981 highlight the connections among infrastructure systems, or between infrastructure reliability, and access to critical services. In addition, infrastructure systems are faced with a host of non-climate stressors (for example, increased demands from growing population, land-use change). As a result, there is high confidence that adaptation efforts designed to address climate impacts across multiple sectors (e.g., Portland-Multnomah County 2014, 201600c8f221-d78e-40bd-a8f3-e28410d1248c,356dccb7-110f-42fb-a7a8-43dcd364f970), as well as those that will yield social environmental co-benefits, will build resilience.

References :

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