Climate Change and Human Health Impacts in the United States: An Update on the Results of the U.S. National Assessment

Ebi, Kristie L.; Mills, David M.; Smith, Joel B.; Grambsch, Anne

Overall, the first HSA concluded that "multiple levels of uncertainty preclude any definitive statement on the direction of potential future change for each of the health outcomes assessed" (Patz et al. 2000) . The literature published since the HSA supports this conclusion, as well as conclusions specific to each health outcome considered. However, this does not mean that there has been no improvement in our understanding of the potential effects of climate variability and change on population health in the United States. For example, recent studies have refined our understanding of the mortality-heat stress relationship and quantified the impact of urban heat islands on ambient temperatures. Similarly, continued development and expansion of morbidity and mortality data sets and advances in epidemiologic modeling techniques have refined the quantitative exposure-response relationships for a number of other health outcome areas. Climate change is expected to increase morbidity and mortality risks from climatesensitive health determinants and outcomes such as extreme heat events and flooding. A larger and relatively older U.S. population in future years will increase overall vulnerability to health risks, depending on the effectiveness of identifying, implementing, and monitoring appropriate adaptation measures.