Malaria, dengue fever, encephalitis, Lyme disease… Up to 58% of the contagious or allergic diseases affecting humanity have at some point been exacerbated by climatic hazards related to greenhouse gas (GHG) emissions. That’s 218 of the 375 known human diseases linked to pathogens. Conversely, 16% of these illnesses were sometimes alleviated. These are the main conclusions of an American study published on August 8th in the journal Nature Climate Change.
The authors, coordinated by Erik Franklin, a geographer from the University of Hawaii, examined the impact of nine climate changes related to greenhouse gases on human diseases caused by pathogens: atmospheric warming, but also drought, heat waves, wildfires, extreme rainfall and floods, warming oceans, increased storms and rising sea levels, and also analyzed another consequence of these emissions, the change in terrestrial vegetation cover.
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“This bibliographical analysis seems pretty serious to me,” says virologist Yannick Simonin von Inserm at the University of Montpellier. The 58% rate needs to be put into perspective, but it has the merit of giving an order of magnitude and drawing attention to the importance of climate change for the increase in human pathogen-related diseases, whether those diseases are emerging or older. »
The Hawaiian team first searched the Google Scholar database for all published studies that presented specific examples of pathogenic diseases affected by one or the other of these climate risks. Overall, the researchers checked more than 77,000 titles. They kept 830 of them who reported an explicit climatic risk (heat waves, flooding, etc.) for a specific disease (malaria, dengue fever, etc.) in a region and/or over a period of time.
More and more zoonoses
Results: 58% of known human pathogenic diseases (ie 218 out of 375) have been affected by at least one of these climate changes at some point. Of these, 160 diseases were aggravated by warming, 122 by excessive rainfall, 121 by flooding, 81 by drought, 71 by storms, 61 by land cover changes, 43 by ocean warming, 21 by fires, 20 by heat waves, and 10 by sea level rises.
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