Climate change may increase the frequency and severity of droughts
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Severe, multiyear droughts have become hotter, drier, and longer since the 1980s. These long-lasting droughts, some of which are extreme enough to be classified as “megadroughts” – can be particularly destructive to agriculture and ecosystems.
Rising temperatures associated with climate change have increased the risk of drought because warmer air can hold more moisture, increasing evaporation from the soil. Coupled with changing precipitation patterns that result in less rain, this can increase and extend drought periods, as has been seen recently. the worst megadroughts of the millennium In parts of North and South America.
Dirk Karger At the Swiss Federal Institute for Forest, Snow and Landscape Research and colleagues, they identified more than 13,000 droughts that lasted at least two years between 1980 and 2018 to reveal long-term trends. They found that since the 1980s, the most severe multi-year droughts have become even drier and hotter.
Droughts have also affected a larger part of the world, with the area affected by the 500 most severe droughts each year extending to about 50,000 square kilometers. “That’s a bigger area than Switzerland,” says Karger.
Satellite images of greenery in drought-affected areas also showed that some ecosystems had turned browner, indicating drier conditions were taking their toll. The most significant change was in temperate grasslands, which are more sensitive to changes in water availability, while tropical and boreal forests were less responsive.
The researchers did not conduct a formal analysis to define the extent to which human-caused climate change contributed to the trend, but the patterns are consistent with what researchers expect as temperatures rise, he says. Benjamin Cook at Columbia University in New York, who was not involved in the research.
The work highlights how long-term drought can have serious consequences, such as climate disasters such as devastating wildfires or powerful hurricanes, Cook says. “For both people and ecosystems, it’s the cumulative impact of droughts that really matters.”
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