Heat-Related Mortality under Two Representative Concentration Pathways (RCPs) Emission Scenarios: Projections for the United States and China

Public health effects associated with rising temperatures resulting from global climate change are expected to increase significantly in this century. Projecting future heat-related mortality is challenging due to considerable uncertainties, and national-level, large-scale impacts under the latest greenhouse gas emission scenarios remain largely unexplored. Here I estimate excess heat-related mortality in the continental United States and in 50 largest metropolitan areas in China in the 2050s under two Representative Concentration Pathways (RCPs) emission scenarios: RCP4.5 and RCP8.5. Using model-simulated future and present climate variables that were dynamically downscaled by regional meteorology models, this study quantifies the potential increase in heat-related mortality during the warm season (May-September) in mid-century relative to the base period of 2000s. The projections are based on an integrated assessment framework that combines high-resolution climate model outputs, location specific temperature-mortality relationships, population projections and baseline mortality rates. Heat mortality risk estimates for both countries are derived from systematic reviews of current literature on temperature-mortality relationships. Potential human adaptation is likely to decrease heat-related mortality in the future. I evaluate future adaptation assumption with a scenario analysis based on empirical evidence of adaptation to heat in both countries. Findings from this study will provide valuable information to support climate policy decision making and heat-related risk management in both countries and globally