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

Additional studies explored the impacts of climate change on urban heat islands and their Climate change and health impacts in the United States Environmental Health Perspectives • VOLUME 114 | NUMBER 9 | September 2006 effects on ambient concentrations of ozone. Taha (2001) projected increases in peak ozone concentrations in Los Angeles and Sacramento, California, by linking output from general circulation models to future emissions inventories and the air pollution models used to evaluate air quality compliance. Related research examined the effect on ambient ozone concentrations of measures to reduce urban heat islands. Sailor (2003) , Taha (1997) , and Taha et al. (2000 Taha et al. ( , 2002 found modeling changes in urban albedo and vegetative cover both increased and decreased ozone concentrations, depending on the location and scenarios considered. The divergent results reflect the strong influence in these models of assumptions about a number of factors affecting ozone formation and resulting ambient concentrations, including the direction of prevailing winds, photochemical mixing, and reaction heights following the implementation of albedo and vegetation changes designed to address the urban heat island. These uncertainties highlight some of the difficulties in projecting future pollutant concentrations under different climate change scenarios.