From 1991 to 2018, over a third of all heat-related deaths were attributable to human-induced global warming, new research has found.
Led by the London School of Hygiene & Tropical Medicine (LSHTM) and the University of Bern within the Multi-Country Multi-City (MCC) Collaborative Research Network, the study analysed data from 732 locations in 43 countries around the world. The results showed, for the first time, the actual contribution of manmade climate change in increasing mortality risks due to heat.
The research has been published in Nature Climate Change.
Overall, the estimates show that 37% of all heat-related deaths in the recent summer periods were caused by the warming of the planet due to anthropogenic activities. The percentage of heat-related deaths attributed to human-induced climate change was highest in Central and South America (up to 76% in Ecuador or Colombia, for example) and South-East Asia (between 48% to 61%).
Dr Ana M. Vicedo-Cabrera, from the University of Bern and first author of the study, said: “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.”
How global warming impacts health
The effects of global warming impacting health include direct links such as wildfires and extreme weather to changes in the spread of vector-borne diseases, amongst other factors. Scenarios of future climate conditions predict a substantial rise in average temperatures, with extreme events such as heatwaves leading to future increases in the related health burden. However, no research has been conducted into what extent these impacts have already occurred in recent decades until now.
This new study focused on manmade global warming through a ‘detection & attribution’ study that identifies, and attributes observed phenomena to changes in climate and weather. Specifically, the team examined past weather conditions simulated under scenarios with and without anthropogenic emissions. This enabled the researchers to separate the warming and related health impact linked with human activities from natural trends. Heat-related mortality was defined as the number of deaths attributed to heat, occurring at exposures higher than the optimum temperature for human health, which varies across locations.
Action on climate change
Professor Antonio Gasparrini from LSHTM, senior author of the study and coordinator of the MCC Network, said: “This is the largest detection & 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. We must act now.”
The authors acknowledge limitations of the study, including being unable to include locations in all regions of the world due to a lack of empirical data.