Severe droughts becoming larger, hotter, drier, and longer

Severe, perennial droughts have become hotter, drier, and more extensive since the 1980s. These prolonged droughts, some of which are so extreme that they are classified as ‘megadroughts’, can have particularly devastating effects on agriculture and ecosystems.

Rising temperatures associated with climate change are increasing the risk of drought by making the air warmer, retaining more moisture, and increasing evaporation from the land. Combined with changes in precipitation patterns that lead to reduced rainfall, this could exacerbate droughts and lengthen their duration. This is evidenced by the recent megadrought in parts of North and South America, the worst in 1,000 years.

dark cargar Researchers from the Swiss Federal Institute for Forestry, Snow and Landscape Research identified more than 13,000 droughts lasting at least two years from 1980 to 2018 to uncover long-term trends. They found that the most severe multi-year droughts since the 1980s have become drier and hotter.

Droughts are also affecting wider areas of the planet, with the area affected by the 500 most severe droughts each year expanding by around 50,000 square kilometers each year. “That’s an area larger than Switzerland,” Karger says.

Satellite images showing green areas in drought-affected areas also show some ecosystems turning brown, indicating that dry conditions are having an effect. The most dramatic changes were seen in temperate grasslands, which are more sensitive to changes in water availability, while tropical and boreal forests showed smaller responses.

The researchers have not conducted a formal analysis to define how much anthropogenic climate change is contributing to this trend, but they say the pattern is consistent with the rise in temperatures researchers expect. states. benjamin cook from Columbia University in New York was not involved in the study.

The study highlights that long-term droughts can have consequences as severe as climate disasters such as devastating wildfires or powerful hurricanes, Cook said. “It’s the cumulative effects of drought, both for humans and ecosystems, that really matter.”