Projected Changes in Temperature-related Morbidity and Mortality in Southern New England.

BACKGROUND: Climate change is expected to result in more heat-related, but potentially fewer cold-related, emergency department visits and deaths. The net effect of projected changes in temperature on morbidity and mortality remains incompletely understood. We estimated the change in temperature-related morbidity and mortality at two sites in southern New England, United States, through the end of the 21st century.

METHODS: We used distributed lag Poisson regression models to estimate the present-day associations between daily mean temperature and all-cause emergency department visits and deaths in Rhode Island and in Boston, Massachusetts. We estimated the change in temperature-related visits and deaths in 2045-2054 and 2085-2094 (relative to 2001-2010) under two greenhouse gas emissions scenarios (RCP4.5 and RCP8.5) using downscaled projections from an ensemble of over 40 climate models, assuming all other factors remain constant.

RESULTS: We observed U-shaped relationships between temperature and morbidity and mortality in Rhode Island, with minima at 10.9°C and 22.5°C, respectively. We estimated that, if this population were exposed to the future temperatures projected under RCP8.5 for 2085-2094, there would be 5,976 (95% eCI = 1,630, 11,379) more emergency department visits but 218 (95% eCI = -551, 43) fewer deaths annually. Results were similar in Boston and similar but less pronounced in the 2050s and under RCP4.5.

CONCLUSIONS: We estimated that in the absence of further adaptation, if the current southern New England population were exposed to the higher temperatures projected for future decades, temperature-related emergency department visits would increase but temperature-related deaths would not.