Projections of Excessive Mortality Related to Diurnal Temperature Range Under Climate Change Scenarios: A Multi-Country Study

Abstract

Background: Various retrospective studies report that a higher diurnal temperature range (DTR) increases mortality risk. This study projects the impact of DTR on future mortality across 445 communities in 20 countries. Methods: We first estimated the DTR-related mortality risk based on the historical daily time-series of mortality and of weather factors from 1985 to 2015. Next, we projected the excess deaths attributable to the DTR during the current (1985–2015) and future (2020–2099) periods using daily DTR series under four climate-change scenarios. We then calculated the future excess deaths based on two assumptions: warmer temperatures affect or do not affect the DTR-mortality risk. Findings: DTR was associated with excess mortality in our time-series analyses. Under the unmitigated scenario, the future average DTR is projected to increase in most countries (-0·4–1·6 °C), and the increasing pattern was more evident in the United States, south-central Europe, Mexico, and South Africa. The excess deaths currently attributable to DTR were estimated to be 0·2–7·4%. Furthermore, the DTR-related mortality risk increased with an increasing average temperature. Based on the positive interactive effect between DTR and temperature, the DTR-related excess deaths are projected to increase in all countries (1·4–10·3%) in 2090–2099. Interpretation: This study suggests that the DTR-related excess mortality may increase globally under climate change, and this increasing pattern may vary between countries. Our findings can contribute to both international and regional public health interventions to reduce the DTR impacts on health under climate change. Funding Statement: Ho Kim is supported by the Korea Ministry of Environment via the “Climate Change Correspondence Program” (2014001310007). Declaration of Interests: All authors report no financial relationships with commercial interests.