Megadroughts Are on the Rise Worldwide
ENVIRONMENT, 27 Jan 2025
Carolyn Gramling | ScienceNews - TRANSCEND Media Service
Prolonged droughts have become longer, more intense and more frequent in the last 30 years. A megadrought in southwestern North America, which affected California’s Nicasio Reservoir, (shown in 2021) topped the list of the 10 most severe events in that period. Justin Sullivan/Getty Images
One of the most extreme megadroughts has helped fuel California’s wildfires.
16 Jan 2025 – Megadroughts are increasing worldwide — and they’re also becoming both hotter and drier.
Over the last 30 years, Earth has experienced an uptick in both frequency and intensity of these punishing, persistent droughts that can last years to decades, researchers report in the Jan. 17 Science. Such lengthy precipitation deficits not only shrink the drinking water supply, but can also lead to massive crop failures, food insecurity, increased tree mortality and increased incidence of wildfire.
The analysis logs the rising global toll of megadroughts from 1980 to 2018. Each year, multiyear droughts affected an additional 5 million hectares of land, physical geographer Liangzhi Chen of the Swiss Federal Institute for Forest, Snow and Landscape Research in Birmensdorf and colleagues found. But the researchers wanted to assess not just the changing scale of the droughts, but also how prolonged droughts impact ecosystems and humans.
Data on precipitation and evapotranspiration — the transfer of water from soil and plants to the atmosphere — allowed the researchers to identify and map megadroughts during that time period, and rank the events by severity. Using satellite data, the team then analyzed changes in regional greenness during the droughts to assess how they affected vegetation.
Nearly every continent on Earth has been subject to megadrought during this period. The worst was southwestern North America’s long-running dry period, which was particularly severe from 2008 to 2014. That drought was the region’s most extreme in 1,200 years and has helped fuel California’s recent bouts with fire, including January’s unusual wintertime wildfires in Los Angeles County.
Globally, grasslands are the ecosystem most affected by megadroughts, the greenness analysis revealed. However, these types of ecosystems appear to be more resilient than other types of vegetation such as tropical and temperate forests, bouncing back relatively soon after a drought ends. And other biomes, such as northern boreal forests, are, despite bouts with dryness, still overall getting greener as the planet warms, as their growing seasons extend.
That may change in the future, the team notes. The growing severity and frequency in Earth’s megadroughts might push even the most resilient ecosystems past their limits.
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Carolyn Gramling is the earth & climate writer. She has bachelor’s degrees in geology and European history and a Ph.D. in marine geochemistry from MIT and the Woods Hole Oceanographic Institution.
Go to Original – sciencenews.org
Tags: California, Climate Change, Drought, Earth, Ecology, Environment, Forest fires, Global warming, Nature, Wild fires
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