Perhaps most strikingly is the increase in mortality and morbidity associated with heat. However, no research has been conducted into what extent these impacts have already occurred in recent decades until now.
‘Recent estimate suggests that one in three heat-related deaths occur due to Global warming with Central and South America and South-East Asia being the most affected regions. However, the study requires further analysis in all world regions including large parts of Africa and South Asia that lacks empirical data.’
Heat-related mortality is defined as the number of deaths attributed to heat, occurring at exposures higher than the optimum temperature for human health, which varies across locations.
Global Warming and Heat-related Mortality
The study team utilized data from 732 locations in 43 countries around the world through a ‘detection & attribution’ study that identifies and attributes observed phenomena to changes in climate and weather. This shows the actual contribution of man-made climate change for the first time in increasing mortality risks due to heat.
It was estimated that overall, 37% of all heat-related deaths in the recent summer periods were attributable to the warming of the planet due to anthropogenic activities and this 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%).
The number of deaths reported from human-induced climate change was as follows:
136 additional deaths per year in Santiago de Chile, which is a total of 44.3% of total heat-related deaths in the city. Others included 189 in Athens (26.1%), 172 in Rome (32%), 156 in Tokyo (35.6%), 177 in Madrid (31.9%), 146 in Bangkok (53.4%), 82 in London (33.6%), 141 in New York (44.2%), and 137 in Ho Chi Minh City (48.5%).
In the UK, 35% 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.
These findings further mandate the need to adopt strong mitigation policies to reduce future warming, and implement interventions to protect populations from the adverse consequences of heat exposure.
Effects of Anthropogenic Emission
“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,” says Dr. Ana M. Vicedo-Cabrera, from the University of Bern and first author of the study.
Depending on the local changes in climate in each area, the vulnerability of its population to heat-related deaths varies. Interestingly, 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.
“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,” says Professor Antonio Gasparrini from LSHTM, senior author of the study and coordinator of the MCC Network.
However, the study requires further analysis in all world regions including large parts of Africa and South Asia that lacks empirical data.