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Thursday, February 22, 2018. 12:30PM. Heat, humidity, and infant mortality in the developing world. Dean Spears, University of Texas, Austin. Sponsored by Climate Futures Initiative. More information here.

Among the potential harms of a warmer Earth are its health impacts, as temperatures in some regions advance beyond the human body’s ability to effectively regulate heat, leading to stroke or death. In this paper, we provide the first econometric evidence on the infant and child mortality effects of extreme heat and humidity in the developing world. We diverge from the prior economics literature in utilizing a humidity-indexed measure of temperature, “wet bulb temperature,” which more closely aligns with the physics of evaporative cooling via sweating than the more familiar “dry bulb” temperature. We show: (i) that exposure to a day of mean temperatures above 85◦F wet bulb—equal to about 100◦F at 50% humidity—leads to an additional one death per thousand births, an effect that is two orders of magnitude larger than prior estimates arising from studies of adults in the developed world; (ii) that accounting for humidity in this context is of first order importance; and (iii) that these effects are not due to “harvesting” (the speeding up of child deaths that would have occurred in any case), implying significant net life years are lost. Our findings represent an important social cost of climate change that has been overlooked in the types of integrated assessment models used to calculate policy parameters like the optimal carbon tax.