There is very high confidence that climate change is affecting the health of Americans. There is high confidence that climate-related health risks, without additional adaptation and mitigation, will likely increase with additional climate change.
' evidence: "Multiple lines of evidence demonstrate statistically significant associations between temperature, precipitation, and other variables and adverse climate-sensitive health outcomes, indicating sensitivity to weather patterns.{{< tbib '1' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} These lines of evidence also demonstrate that vulnerability varies across sub-populations and geographic areas; populations with higher vulnerability include poor people in high-income regions, minority groups, women, children, the disabled, those living alone, those with poor health status, Indigenous people, older adults, outdoor workers, people displaced because of weather and climate, low-income residents that lack a social network, poorly planned communities, communities disproportionately burdened by poor environmental quality, the disenfranchised, those with less access to healthcare, and those with limited financial resources to rebound from disasters.{{< tbib '108' 'b9638744-8ff8-41bd-a741-27b2fda9face' >}},{{
The chapter evaluated the scientific evidence of the health risks of climate change, focusing primarily on the literature published since the cut off date (approximately fall 2015) of the U.S. Climate and Health Assessment.{{< tbib '1' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} A comprehensive literature search was performed by federal contractors in December 2016 for studies published since January 1, 2014, using PubMed, Scopus, and Web of Science. An Excel file containing 2,477 peer-reviewed studies was provided to the author team for it to consider in this assessment. In addition to the literature review, the authors considered recommended studies submitted in comments by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The focus of the literature was on health risks in the United States, with limited citations from other countries providing insights into risks Americans are or will likely face with climate change. A full description of the search strategy can be found at https://www.niehs.nih.gov/CCHH_Search_Strategy_NCA4_508.pdf. The chapter authors were chosen based on their expertise in the health risks of climate change. Teleconferences were held with interested researchers and practitioners in climate change and health and with authors in other chapters of this Fourth National Climate Assessment (NCA4).
The U.S. Climate and Health Assessment{{< tbib '1' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} did not consider adaptation or mitigation, including economic costs and benefits, so the literature cited includes research from earlier years where additional information was relevant to this assessment.
For NCA4, Air Quality was added as a report chapter. Therefore, while Key Messages in this Health chapter include consideration of threats to human health from worsened air quality, the assessment of these risks and impacts are covered in Chapter 13: Air Quality. Similarly, co-benefits of reducing greenhouse gas emissions are covered in the Air Quality chapter.
" report_identifier: nca4 statement: 'The health and well-being of Americans are already affected by climate change (very high confidence), with the adverse health consequences projected to worsen with additional climate change (likely, high confidence). Climate change affects human health by altering exposures to heat waves, floods, droughts, and other extreme events; vector-, food- and waterborne infectious diseases; changes in the quality and safety of air, food, and water; and stresses to mental health and well-being.
' uncertainties: 'The role of non-climate factors, including socioeconomic conditions, population characteristics, and human behavior, as well as health sector policies and practices, will continue to make it challenging to attribute injuries, illnesses, and deaths to climate change. Inadequate consideration of these factors creates uncertainties in projections of the magnitude and pattern of health risks over coming decades. Certainty is higher in near-term projections where there is greater understanding of future trends.
' uri: /report/nca4/chapter/human-health/finding/key-message-14-1 url: ~ - chapter_identifier: human-health confidence: 'There is high confidence that climate change is disproportionately affecting the health of children, older adults, low-income communities, communities of color, tribal and Indigenous communities, and many other distinct populations. And there is high confidence that some of the most vulnerable populations experience greater barriers to accessing resources, information, and tools to build resilience.
' evidence: "Multiple lines of evidence demonstrate that low-income communities and some communities of color are experiencing higher rates of exposure to adverse environmental conditions and social conditions that can reduce their resilience to the impacts of climate change.{{< tbib '106' 'c76d7935-9da3-4c4b-9186-86dc658bcc74' >}},{{
Adaptation can increase the climate resilience of populations when the process of developing and implementing policies and measures includes understanding the ethical and human rights dimensions of climate change, meeting human needs in a sustainable and equitable way, and engaging with representatives of the most impacted communities to assess the challenges they face and to define the climate solutions.{{< tbib '124' '7f89e40a-7681-4475-a754-91e81baabd95' >}},{{
The chapter evaluated the scientific evidence of the health risks of climate change, focusing primarily on the literature published since the cut off date (approximately fall 2015) of the U.S. Climate and Health Assessment.{{< tbib '1' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} A comprehensive literature search was performed by federal contractors in December 2016 for studies published since January 1, 2014, using PubMed, Scopus, and Web of Science. An Excel file containing 2,477 peer-reviewed studies was provided to the author team for it to consider in this assessment. In addition to the literature review, the authors considered recommended studies submitted in comments by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The focus of the literature was on health risks in the United States, with limited citations from other countries providing insights into risks Americans are or will likely face with climate change. A full description of the search strategy can be found at https://www.niehs.nih.gov/CCHH_Search_Strategy_NCA4_508.pdf. The chapter authors were chosen based on their expertise in the health risks of climate change. Teleconferences were held with interested researchers and practitioners in climate change and health and with authors in other chapters of this Fourth National Climate Assessment (NCA4).
The U.S. Climate and Health Assessment{{< tbib '1' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} did not consider adaptation or mitigation, including economic costs and benefits, so the literature cited includes research from earlier years where additional information was relevant to this assessment.
For NCA4, Air Quality was added as a report chapter. Therefore, while Key Messages in this Health chapter include consideration of threats to human health from worsened air quality, the assessment of these risks and impacts are covered in Chapter 13: Air Quality. Similarly, co-benefits of reducing greenhouse gas emissions are covered in the Air Quality chapter.
" report_identifier: nca4 statement: 'People and communities are differentially exposed to hazards and disproportionately affected by climate-related health risks (high confidence). Populations experiencing greater health risks include children, older adults, low-income communities, and some communities of color (high confidence).
' uncertainties: "The role of non-climate factors, including socioeconomic conditions, discrimination (racial and ethnic, gender, persons with disabilities), psychosocial stressors, and the continued challenge to measure the cumulative effects of past, present, and future environmental exposures on certain people and communities will continue to make it challenging to attribute injuries, illnesses, and deaths to climate change. While there is no universal framework for building more resilient communities that can address the unique situations across the United States, factors integral to community resilience include the importance of social networks, the value of including community voice in the planning and execution of solutions, and the co-benefits of institutional readiness to address the physical, health, and social needs of impacted communities. These remain hard to quantify.{{< tbib '127' 'cab3885c-a808-40f4-9b4a-79808bbdf202' >}},{{
There is medium confidence that with sufficient human and financial resources, adaptation policies and programs can reduce the current burden of climate-sensitive health outcomes.{{< tbib '110' '289728b3-ae8b-417e-920e-96af1a5e64b3' >}},{{
Health adaptation is taking place from local to national scales.{{< tbib '129' 'a6d2d472-b084-4805-9f08-cc5e1f95f668' >}},{{
The chapter evaluated the scientific evidence of the health risks of climate change, focusing primarily on the literature published since the cut off date (approximately fall 2015) of the U.S. Climate and Health Assessment.{{< tbib '1' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} A comprehensive literature search was performed by federal contractors in December 2016 for studies published since January 1, 2014, using PubMed, Scopus, and Web of Science. An Excel file containing 2,477 peer-reviewed studies was provided to the author team for it to consider in this assessment. In addition to the literature review, the authors considered recommended studies submitted in comments by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The focus of the literature was on health risks in the United States, with limited citations from other countries providing insights into risks Americans are or will likely face with climate change. A full description of the search strategy can be found at https://www.niehs.nih.gov/CCHH_Search_Strategy_NCA4_508.pdf. The chapter authors were chosen based on their expertise in the health risks of climate change. Teleconferences were held with interested researchers and practitioners in climate change and health and with authors in other chapters of this Fourth National Climate Assessment (NCA4).
The U.S. Climate and Health Assessment{{< tbib '1' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} did not consider adaptation or mitigation, including economic costs and benefits, so the literature cited includes research from earlier years where additional information was relevant to this assessment.
For NCA4, Air Quality was added as a report chapter. Therefore, while Key Messages in this Health chapter include consideration of threats to human health from worsened air quality, the assessment of these risks and impacts are covered in Chapter 13: Air Quality. Similarly, co-benefits of reducing greenhouse gas emissions are covered in the Air Quality chapter.
" report_identifier: nca4 statement: 'Proactive adaptation policies and programs reduce the risks and impacts from climate-sensitive health outcomes and from disruptions in healthcare services (medium confidence). Additional benefits to health arise from explicitly accounting for climate change risks in infrastructure planning and urban design (low confidence).
' uncertainties: "Overall, while there is considerable evidence of the effectiveness of public health programs,{{< tbib '110' '289728b3-ae8b-417e-920e-96af1a5e64b3' >}},{{
There is a high confidence that a reduction in greenhouse gas emissions would benefit the health of Americans. There is medium confidence that reduced greenhouse gas emissions under RCP4.5 compared to RCP8.5 will likely reduce lost labor hours by almost half and avoid thousands of premature deaths and illnesses projected each year from climate impacts on extreme heat, ozone and aeroallergen levels (Ch. 13: Air Quality), and West Nile neuroinvasive disease. There is medium confidence that the economic benefits of greenhouse gas emissions reductions in the health sector could likely be on the order of hundreds of billions of dollars each year by the end of the century. Including avoided or reduced benefits of risks that are difficult to quantify, such as mental health or long-term health consequences, would increase these estimates.
" evidence: "Benefits of mitigation associated with air quality, including co-benefits of reducing greenhouse gas emissions, can be found in Chapter 13: Air Quality. This Key Message is consistent with and inclusive of those findings.
Multiple individual lines of evidence across several health topic areas demonstrate significant benefits of greenhouse gas emission reductions, with health impacts and health-related costs reduced by approximately half under RCP4.5 compared to RCP8.5 by the end of the century, based on comprehensive multisector quantitative analyses of economic impacts projected under consistent scenarios (Ch. 13: Air Quality).{{< tbib '37' '4308e866-5976-4181-8102-24b521ff4033' >}},{{
Heat: Greenhouse gas emission reductions under RCP4.5 could substantially reduce the annual number of heat wave days (for example, by 21 in the Northwest and by 43 in the Southeast by the end of the century);{{< tbib '161' 'a5d430bc-5756-42d1-924f-3dbc927e69c4' >}} the number of high-mortality heat waves;{{< tbib '162' 'f9703346-dc6b-4b3e-aad6-2643c74f5292' >}},{{
Labor productivity: Hsiang et al. (2017){{< tbib '167' 'fad9e8ec-8951-4daa-9a9c-e093ef86af16' >}} and the EPA (2017){{< tbib '157' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}} estimated the number of labor hours from changes in extreme temperatures using dose–response functions for the relationship between temperature and labor from Graff Zivin and Neidell (2014).{{< tbib '169' '8f2308d0-7a25-4c47-82e0-cb9196f1de8b' >}} Under RCP8.5, almost 2 billion labor hours are projected to be lost annually by 2090 from the impacts of extreme heat and cold, costing an estimated $160 billion in lost wages. The Southeast{{< tbib '164' 'bbca6337-718b-4289-b6e7-0a2f6c1cb8f1' >}},{{
Vector-borne disease: Belova et al. (2017){{< tbib '37' '4308e866-5976-4181-8102-24b521ff4033' >}} and the EPA (2017){{< tbib '157' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}} define health impact functions from regional associations between temperatures and the probability of above-average West Nile neuroinvasive disease (WNND) incidence to estimate county-level expected WNND incidence rates for a 1995 reference period (1986–2005) and two future years (2050: 2040–2059 and 2090: 2080–2099) using temperature data from five GCMs. Annual national cases of WNND are projected to more than double by 2050 due to increasing temperatures, resulting in approximately $1 billion per year in hospitalization costs and premature deaths. In 2090, an additional 3,300 annual cases are projected under RCP8.5, with $3.3 billion per year in costs. Greenhouse gas emission reductions under RCP4.5 could avoid approximately half these cases and costs.
Water quality: Chapra et al. (2017){{< tbib '165' '28077cd1-c29f-48ae-a068-2cdcef880807' >}} and the EPA (2017){{< tbib '157' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}} evaluate the biophysical impacts of climate change on the occurrence of cyanobacterial harmful algal blooms in the contiguous United States using models that project rainfall runoff, water demand, water resources systems, water quality, and algal growth. In 2090, warming under RCP8.5 is projected to increase the length of time that recreational waters have concentrations of harmful algal blooms (cyanobacteria) above the recommended public health threshold by one month annually; greenhouse gas emissions under RCP4.5 could reduce this by two weeks.
Food safety and nutrition: There is limited evidence quantifying specific health outcomes or economic impacts of reduced food safety and nutrition.
" href: https://data.globalchange.gov/report/nca4/chapter/human-health/finding/key-message-14-4.yaml identifier: key-message-14-4 ordinal: 4 process: "The chapter evaluated the scientific evidence of the health risks of climate change, focusing primarily on the literature published since the cut off date (approximately fall 2015) of the U.S. Climate and Health Assessment.{{< tbib '1' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} A comprehensive literature search was performed by federal contractors in December 2016 for studies published since January 1, 2014, using PubMed, Scopus, and Web of Science. An Excel file containing 2,477 peer-reviewed studies was provided to the author team for it to consider in this assessment. In addition to the literature review, the authors considered recommended studies submitted in comments by the public, the National Academies of Sciences, Engineering, and Medicine, and federal agencies. The focus of the literature was on health risks in the United States, with limited citations from other countries providing insights into risks Americans are or will likely face with climate change. A full description of the search strategy can be found at https://www.niehs.nih.gov/CCHH_Search_Strategy_NCA4_508.pdf. The chapter authors were chosen based on their expertise in the health risks of climate change. Teleconferences were held with interested researchers and practitioners in climate change and health and with authors in other chapters of this Fourth National Climate Assessment (NCA4).
The U.S. Climate and Health Assessment{{< tbib '1' 'f1e633d5-070a-4a7d-935b-a2281a0c9cb6' >}} did not consider adaptation or mitigation, including economic costs and benefits, so the literature cited includes research from earlier years where additional information was relevant to this assessment.
For NCA4, Air Quality was added as a report chapter. Therefore, while Key Messages in this Health chapter include consideration of threats to human health from worsened air quality, the assessment of these risks and impacts are covered in Chapter 13: Air Quality. Similarly, co-benefits of reducing greenhouse gas emissions are covered in the Air Quality chapter.
" report_identifier: nca4 statement: 'Reducing greenhouse gas emissions would benefit the health of Americans in the near and long term (high confidence). By the end of this century, thousands of American lives could be saved and hundreds of billions of dollars in health-related economic benefits gained each year under a pathway of lower greenhouse gas emissions (likely, medium confidence).
' uncertainties: 'While projections consistently indicate that changes in climate are expected to have negative health consequences, quantifying specific health outcomes (for example, number of cases, number of premature deaths) remains challenging, as noted in Key Message 1. Economic estimates only partially capture and monetize impacts across each health topic area, which means that damage costs are likely to be an undervaluation of the actual health impacts that would occur under any given scenario. Economic estimates in this chapter do not include costs to the healthcare system.
' uri: /report/nca4/chapter/human-health/finding/key-message-14-4 url: ~