Climate change linked to a third of heat-related deaths, study finds

Researchers at the London School of Hygiene & Tropical Medicine (LSHTM) and the University of Bern used data from 732 locations in 43 countries around the world to demonstrate the actual contribution of man-made climate change in increasing mortality risks due to heat.

Overall, the estimates show that 37 per cent of all heat-related deaths in the recent summer periods were attributable to the warming of the planet due to human activities. This percentage of heat-related deaths attributed to human-induced climate change was highest in Central and South America (up to 76 per cent in Ecuador or Colombia, for example) and South-East Asia (between 48 to 61 per cent).

The authors say their findings are further evidence of the need to adopt strong mitigation policies to reduce future warming, and to implement interventions to protect populations from the adverse consequences of heat exposure.

First author of the study Dr Ana M. Vicedo-Cabrera 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.”

The study warns that with future climate conditions predicting a substantial rise in average temperatures, extreme events such as heatwaves could lead to further increases in the number of heat deaths.

The team examined past weather conditions simulated under scenarios with and without manmade emissions. This enabled them 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.

While on average over a third of heat-related deaths are due to human-induced climate change, impact varies substantially across regions.

Climate-related heat casualties range from a few dozen to several hundred deaths each year per city, depending on the local changes in climate in each area and the vulnerability of its population.

Populations living in low and middle-income countries, which were responsible for a minor part of anthropogenic emissions in the past, are those most affected.

In the UK, 35 per cent of heat-related deaths could be attributed to human-induced climate change, which corresponds to approximately 82 deaths in London, 16 deaths in Manchester, 20 in West Midlands or 4 in Bristol and Liverpool every summer season.

“This is the largest detection & attribution study on current health risks of climate change,” said the senior author of the study Professor Antonio Gasparrini from LSHTM.

“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.”