Climate change can increase the frequency and severity of droughts
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Grave droughts that have persisted for years have become warmer, drier and larger since the 1980s. These lasting droughts – some of which are extreme enough to be classified as “megadroughs– can be particularly devastating for agriculture and ecosystems.
The rise in temperatures related to climate change has increased the risk of drought because the warmer air can contain more humidity, stimulating the evaporation of the earth. Combined with the evolution of the precipitation patterns which lead to less rain, this can exacerbate and lengthen the periods of drought – as evidenced by the recent Worse-millennium megadroughs In certain parts of North and South America.
Dirk Karger At the Swiss Federal Institute for Forest Research, Snow and Landscape and its colleagues identified more than 13,000 droughts which lasted at least two years between 1980 and 2018 to reveal long -term trends. They have found that, since the 1980s, the most serious multi -year droughts have become even drier and warmer.
The droughts also affected a larger part of the globe, the area affected by the 500 most serious drought events in progress during a given year increased by approximately 50,000 square kilometers per year. “It is a larger area than Switzerland,” says Karger.
Satellite greenery images in areas affected by drought also showed that certain ecosystems have become brighter, indicating that dry conditions had an effect. The most spectacular change was in temperate meadows, which are more sensitive to changes in water availability, while tropical and boreal forests have shown a smaller response.
The researchers did not do formal analysis to define the amount of climate change of human origin which contributed to the trend, but the models are consistent with what the researchers expect to do with the increase in temperatures, says Benjamin Cook At Columbia University in New York, which was not involved in research.
The work highlights the long -term drought which can have consequences as serious as climatic disasters such as destructive forest fires or powerful hurricanes, explains Cook. “For people and ecosystems, the cumulative impact of droughts is really what matters.”
