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

Current health status and trends in the United States. The HSA (Patz et al. 2000) noted a number of population subgroups that are likely to be more vulnerable to the adverse impacts of a changing climate, including the very young (i.e., < 1 year of age), older adults (i.e., those ≥ 65 years of age), and immunocompromised individuals. These groups are often at the greatest risk for climatesensitive health outcomes because they are more sensitive to vector-, food-, and water-borne diseases, have limited capacity to acclimatize to thermal extremes, and have reduced ability to undertake appropriate behavioral changes when exposed to thermal extremes and extreme weather events. Therefore, we reviewed U.S. population projections and public health sector trends to evaluate the potential future changes in the vulnerability of susceptible groups to the health impacts of climate change. Table 2 summarizes U.S. population estimates for various age groups from 2000 to 2100 (U.S. Census Bureau 2002) . Most notable is the anticipated increase in the size and proportion of the total population accounted for by older adults. By 2100, projections suggest that there will be approximately 100 million more citizens ≥ 65 years of age than in 2000. The combined share of the population that will be composed of the very young and older adults is projected to increase from about 15% to > 25%. The anticipated increase in these age groups suggests, all else equal, that the U.S. population will become increasingly vulnerable to the health impacts of climate change.