Over the last three decades, human-induced global warming has caused more than one-third of all heat-related deaths. The finding, published in Nature Climate Change, looked at deaths between 1991 and 2018 from 43 countries around the world. On average 37 percent of all deaths in which heat played a role are attributable to the effects of the climate crisis.
There is huge variation in terms of macro-regions and specific localities, with many places having much higher rates. The highest percentages where heat-related deaths were attributed to climate change were South America and Southeast Asia. In Ecuador and Colombia, for example, it was up to 76 percent. There Is also huge variation in major cities. Santiago de Chile and New York City experienced similar percentages, experiencing an additional 136 and 144 heat-related deaths per year.
Global warming affects human health in multiple ways. Making people more susceptible to getting ill and dying due to heat is just one of them. To differentiate the heat-related deaths due to climate change from other factors, the team looked at scenarios for weather conditions in which there has not been any anthropogenic global warming as well as how greenhouse emissions impacted the actual climate. Armed with that, the team was able to distinguish the extra impact that climate change has brought.
"We expect the proportion of heat-related deaths to continue to grow if we don't do something about climate change or adapt. So far, the average global temperature has only increased by about 1°C, which is a fraction of what we could face if emissions continue to grow unchecked," lead author Dr Ana M. Vicedo-Cabrera from the University of Bern said in a statement.
The study's findings suggest that the climate crisis is already affecting humanity more than realized, or acknowledged, and more ambition is required by global governments to mitigate global warming. Better public health measures also need to be put in place to minimize the increased risks that people are experiencing due to the anthropogenic climate crisis.
The study provides some important insights but the researchers acknowledge its limitation as it only included a small number of countries and had limited data on large areas of Africa and South Asia where the impact of the climate crisis has already been devastating in many other ways.
"This is the largest detection and attribution study on current health risks of climate change. The message is clear: climate change will not just have devastating impacts in the future, but every continent is already experiencing the dire consequences of human activities on our planet," senior author Professor Antonio Gasparrini from the London School of Hygiene & Tropical Medicine, said. "We must act now."