Emory researchers are part of a sweeping new study that finds that more than one in three heat-related deaths can be attributed to human-made climate change.

Rollins School of Public Health assistant professor Noah Scovronick, PhD, is second author on the paper which published this week in Nature Climate Change.  

Using empirical heat-related data from 732 cities in 43 countries around the world between 1991–2018, the researchers found that 37 percent of heat-related deaths can be directly attributed to anthropogenic (or human-induced) climate change and that increased mortality is evident on every continent.

The international study was coordinated by the University of Bern and the London School of Hygiene & Tropical Medicine and was conducted by 70 researchers.

Scenarios of future climate conditions predict a substantial rise in average temperatures and extreme events such as heatwaves and have theorized about its toll on the health of people. However, so far, no study has evaluated if and to what extent these effects have already been experienced in recent decades. This study, which identified and attributed observed phenomena to changes in climate and weather, now provides evidence on this topic.

The researchers examined past weather conditions projected under scenarios with and without emissions, enabling them to separate global warming and related health impact that are linked with human activity from natural trends.

The impact varies substantially across locations. The number of climate-related heat casualties ranges from a few dozen to several hundred deaths each year, depending on local changes in climate and the vulnerability of its populations. Interestingly, people living in low and middle-income countries, which have played a minor part in anthropogenic emissions, are those most affected, with the proportion of human-induced heat-related mortality higher in Central and South America and Southeast Asia.

In the United States, the study found that 34.7 percent of all heat-related summer deaths were attributable to anthropogenic climate change. In Atlanta, 24.3 percent of summer deaths could be attributed to anthropogenic climate change; on average, around 19 people died in the city each year due to human-induced climate change. 

“This study shows us that the impacts of climate change are already upon us and are being felt all over the world,” says Scovronick. “The southeastern United States is no exception. This work provides another reminder of the need to reduce emissions of greenhouse gases and to implement policies to protect the people most at risk.”