More than 13,000 droughts spanning years have overwhelmed our planet across nearly four decades. These severe droughts are becoming hotter, longer and more devastating as our planet’s global temperature increases, new research has found.
“We need awareness of these ‘new’ type of droughts, which last for more than one season or year,” said Francesca Pellicciotti, a hydrologist at the Institute of Science and Technology Austria and co-author of the study published Thursday. “Their effects are amplified — up to the point that some of these systems will not recover anymore.”
While there is more evidence that multiyear events are increasing, Pellicciotti said no one had characterized these long-term droughts across the globe and their impacts — until now.
The team analyzed 13,176 multiyear droughts from 1980 to 2018 through two perspectives: a meteorological standpoint, which largely looked at rainfall as well as temperature, and the ecological impact on vegetation, which helped the researchers gauge the severity.
They found that precipitation deficits in the top 100 multiyear droughts increased over the past four decades. The droughts were also getting hotter, in tandem with global average air temperatures also increasing in recent decades. The years with the largest droughts also followed El Niño events.
Measuring the health of vegetation using satellite data, the researchers found that droughts with the most impactful effects occurred in temperate grasslands — with hot spots in Mongolia, the western United States and eastern Australia.
The study’s results “add to the growing consensus that we can expect larger, more frequent and more intense droughts as the planet warms,” said Matt Rodell, a hydrologist at NASA who was not involved in the study.
In a separate study, Rodell and his colleague showed a notable increase in the frequency of both major droughts and extreme wet events after 2015 — all of which have been among Earth’s top 10 warmest years on record.