Climate change impacts human health in both direct and indirect ways^{1 ,2} . Extreme heat waves, rising sea level, changes in precipitation resulting in flooding and droughts, and intense hurricanes can directly cause injury, illness, and even death³ . The effects of climate change can also indirectly affect health through alterations to the environment. For example, worsening air pollution levels can have negative impacts on respiratory and cardiovascular conditions⁴ . Changes in temperature and rainfall can alter the survival, distribution, and behavior of insects and other species that can lead to changes in infectious diseases⁵ . Increases in precipitation, storm surge, and sea temperature can lead to more water-related illnesses⁶ . Climate change can also affect food safety, exposing people to contaminated foods that can result in foodborne illnesses⁷ . In addition, climate change can affect mental health and well-being^{8 ,9} .

Exposure to climate-related hazards can include biological, chemical, or physical stressors and can differ in time, locations, populations, and severity. These are referred to as exposure pathways. These threats can occur simultaneously, resulting in compounding health impacts. Climate change threats may also accumulate over time, leading to longer-term changes in resilience and health.

Climate change can affect human health by changing the severity, duration, or frequency of health problems and by creating unprecedented or unanticipated health problems or health threats in places or populations where they have not previously occurred¹⁰ . While everyone is exposed to climate-related health threats, not everyone experiences the same harms. Individuals may experience greater risk from climate-related health effects because: they have greater exposure to climate-related hazards; they are more sensitive to the effects of climate stressors; their own present state of health and wellbeing; or they do not have sufficient capacity or resources to cope or remove themselves from harm¹¹ . An effective public health response to mitigate the risks of climate change is essential to preventing injuries and illnesses and enhancing overall public health preparedness.

NIEHS supports research that can be used to make decisions that can help reduce the threats of climate change. In the 2016 report by the U.S. Global Change Research Program, The Impacts of Climate Change on Human Health: A Scientific Assessment, the Interagency Working Group on Climate Change and Health describes seven different types of health threats that help outline the major research areas. These include the following:

• Foodborne Illness and Nutrition
• Health Impacts of Air Quality
• Health Impacts of Extreme Weather Events
• Mental Health and Well-being
• People Who Are Vulnerable to Climate Change
• Temperature-Related Death and Illness
• Vector-borne Diseases
• Water-related Illnesses

Figure 2: The diagram shows specific examples of how climate change can affect human health, now and in the future. (Graphic courtesy of GlobalChange.gov)

1. Ebi K.L, Balbus JM, Luber G, Bole A, Crimmins A, Glass G, Saha S, Shimamoto MM, Trtanj J, and White-Newsome JL. 2018: Human Health. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, pp. 539–571. doi: 10.7930/NCA4. 2018. CH14. [Full Text Ebi K.L, Balbus JM, Luber G, Bole A, Crimmins A, Glass G, Saha S, Shimamoto MM, Trtanj J, and White-Newsome JL. 2018: Human Health. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, pp. 539–571. doi: 10.7930/NCA4. 2018. CH14.]
2. IPCC, 2022: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press. In Press. [Full Text IPCC, 2022: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press. In Press.]
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4. Mills, Nicholas L., et al. Adverse cardiovascular effects of air pollution. Nature Clinical Practice Cardiovascular Medicine 6.1 (2009): 36-44. [Full Text Mills, Nicholas L., et al. Adverse cardiovascular effects of air pollution. Nature Clinical Practice Cardiovascular Medicine 6.1 (2009): 36-44.]
5. Hunter, Paul R. Climate change and waterborne and vector‐borne disease. Journal of Applied Microbiology 94 (2003): 37-46. [Full Text Hunter, Paul R. Climate change and waterborne and vector‐borne disease. Journal of Applied Microbiology 94 (2003): 37-46.]
6. Rose, Joan B., et al. Climate variability and change in the United States: potential impacts on water-and foodborne diseases caused by microbiologic agents. Environmental Health Perspectives 109.suppl 2 (2001): 211-221. [Full Text Rose, Joan B., et al. Climate variability and change in the United States: potential impacts on water-and foodborne diseases caused by microbiologic agents. Environmental Health Perspectives 109.suppl 2 (2001): 211-221.]
7. Lake, Iain R., et al. A re-evaluation of the impact of temperature and climate change on foodborne illness. Epidemiology & Infection 137.11 (2009): 1538-1547. [Full Text Lake, Iain R., et al. A re-evaluation of the impact of temperature and climate change on foodborne illness. Epidemiology & Infection 137.11 (2009): 1538-1547.]
8. Cissé, G., R. McLeman, H. Adams, P. Aldunce, K. Bowen, D. Campbell-Lendrum, S. Clayton, K.L. Ebi, J. Hess, C. Huang, Q. Liu, G. McGregor, J. Semenza, and M.C. Tirado, 2022: Health, Wellbeing, and the Changing Structure of Communities. In: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press. In Press. [Full Text Cissé, G., R. McLeman, H. Adams, P. Aldunce, K. Bowen, D. Campbell-Lendrum, S. Clayton, K.L. Ebi, J. Hess, C. Huang, Q. Liu, G. McGregor, J. Semenza, and M.C. Tirado, 2022: Health, Wellbeing, and the Changing Structure of Communities. In: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press. In Press.]
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11. Benevolenza MA, DeRigne L. 2019. The impact of climate change and natural disasters on vulnerable populations: A systematic review of literature, Journal of Human Behavior in the Social Environment. 29:2, 266-281. [Abstract Benevolenza MA, DeRigne L. 2019. The impact of climate change and natural disasters on vulnerable populations: A systematic review of literature, Journal of Human Behavior in the Social Environment. 29:2, 266-281.]