According to a study released on Monday, more than one-third of worldwide heatwave deaths are directly caused by global warming.
To carry out this rare study of the cause of global warming in the context of public health, 70 international researchers compiled data from 732 sites in 43 countries over the period between 1991 and 2018.
They then used a complex method to calculate from health data, temperature readings, and climate models, the difference between the number of heat-related deaths and the number of deaths that would have been expected without warming.
And according to the results of their calculations published in the journal Nature Climate Change, an average of 37% of heat-related deaths are directly caused by warming results.
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According to the researchers, as a result of this, 100,000 deaths per year will be related to heat and its direct cause will be climate change. This figure may be underestimated because there is a lack of data for some regions of the world, particularly those affected by heat waves, such as Central Africa or South Asia.
In developed countries, the United States, Australia, France, Great Britain or Spain, the number of deaths due to warming varies from 35% to 39%, but in countries such as Mexico, South Africa, Thailand, Vietnam, it averages 40. Rises above%. Or Chile. And it is more than 60% in some countries like Brazil, Peru, Colombia, Philippines, Kuwait or Guatemala.
Negative impact
These results suggest that “climate change is not something that comes from the distant future,” explains Antonio Gasparini, the study’s lead author and professor at the London School of Hygiene and Tropical Medicine. “We can measure negative impacts on health, in addition to previously known environmental and ecological impacts.”
A 2019 study published in the Lancet estimated 300,000 deaths per year associated with heatwave, which scientists warned would continue to increase the effects of climate change, such as in 2003, around 70,000 people died in Europe.
This mortality is not particularly due to the gross increase in summer temperatures (1.5 ° C since 1991 in the areas concerned by the study). The duration of heat waves, an increase in nighttime temperature or humidity levels in comparison to the day plays a particularly important role.
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The technique of coping may also play a role. Thus mortality may decrease with the spread of air conditioning. But it itself consumes energy and therefore contributes to warming …
Studies on the implantation of warming consequences, particularly on extreme weather events, have gained momentum in recent years, but are still quite rare in relation to outcomes on human health, underscores university researcher Dan Mitchell. From Bristol (Great Britain)), in a commentary on the study published by Nature Climate Change. “This change in perspective is necessary for world leaders to understand the risks.”