A Comparative Assessment of Changes in Heat-Related Mortality Risk Under the RCP2.6 and RCP8.5 Scenarios Based on the CORDEX-CORE Ensembles

Abstract

This study assesses the future heat-related mortality risk under varying levels of warming specified by the RCP2.6 and RCP8.5 scenarios using dynamically downscaled ensemble projections across six different domains. The excess mortality risk due to heat is estimated by the empirical relationship between daily maximum temperature (Tmax) and mortality. The changes in heat-related mortality based on three empirical formulas derived from different countries’ data are compared to examine the sensitivity of change patterns to the empirical formula. The ensemble projections reveal a drastic increase in heat-related mortality risk under the RCP8.5 scenario. However, a significant reduction is expected by limiting greenhouse gas emissions to the RCP2.6 level. While mitigation’s possible benefit is clearly exemplified by comparing the mortality risk derived from RCP2.6 and RCP8.5 projections, this study also provides valuable insights into regional hotspots by comparing the results from multi-domains. Regardless of the emission scenario (RCP2.6 vs. RCP8.5) and empirical formulas that represent the relationship between temperature and mortality, the most vulnerable regions to heat-related mortality risk are identified in the low-latitude near the equator where the adaptation capacities to avoid serious consequences are found to be poor. The higher risk of heat-related mortality in the future is largely attributable to a significant increase in frequency exceeding the optimum temperature where the mortality risk is minimum during the historical period.