Extreme weather events in which a heat wave triggers a sudden, severe drought have been spreading across the globe at an accelerating pace, according to a study published Friday in the journal Science Advances. Researchers from South Korea and Australia found that by 2023, these heat-first drought extremes covered as much as 16.7% of Earth’s land in a given year — up from roughly 2.5% in the 1980s.
The findings highlight how climate-driven extremes can compound each other, with heat waves not merely co-occurring with drought but actively triggering faster and more severe dry conditions — a dynamic that leaves farmers and communities with little time to prepare.
What the study found
The research examined what scientists call compound extreme weather — cases in which heat and drought occur together. Researchers paid particular attention to sequences in which heat strikes first, because that order produces stronger droughts than when drought precedes heat or occurs without it, said co-author Sang-Wook Yeh, a climate scientist at Hanyang University in South Korea.
Lead author Yong-Jun Kim, also a Hanyang climate scientist, said that onset speed is what makes heat-triggered drought especially damaging. When air warms, it draws more moisture from soil at a rapid pace, producing what scientists call “flash droughts” — dry spells that arrive too quickly for people and farmers to prepare.
The 10-year average for land covered by heat-first drought extremes reached 7.9% by the end of the study period, with a single-year peak of 16.7% in 2023. The rate of increase over the final 22 years studied was eight times higher than in the two preceding decades, the authors said.
A change point around 2000
Kim and Yeh said they identified a change point around the year 2000 after which the spread of heat-then-drought events accelerated sharply. They speculated that Earth may have crossed a “tipping point” at which the shift is irreversible, though they acknowledged difficulty in determining whether the changes are permanent.
Jennifer Francis, a climate scientist at the Woodwell Climate Research Center who was not part of the study, said the change point was “eerily coincident with the onset of rapid Arctic warming, sea-ice loss, and decline in spring snow cover on Northern Hemisphere continents.”
Gerald Meehl, a climate scientist at the National Center for Atmospheric Research who also was not part of the study, said several aspects of Earth’s climate changed in the late 1990s, with a possible trigger being the major El Niño event of 1997–98. He added that it is hard to tell whether those changes are permanent.
Where the increases are largest
The study found the biggest increases in heat-triggered droughts in South America, western Canada, Alaska, the western United States, and parts of central and eastern Africa.
Andrew Weaver, a climate scientist at the University of Victoria in British Columbia and a former Canadian legislator, said the 2021 Pacific Northwest heat dome illustrated how quickly these compound extremes can escalate. Weaver, who was not part of the study, wrote in an email: “Temperatures near 50°C (122 degrees Fahrenheit) in Lytton (British Columbia) were followed by rapid drying and extreme wildfire conditions that destroyed the community.”
Kim cited additional examples: the 2022 heat and drought around China’s Yangtze River and the 2023–24 record heat and drought in the Amazon. Weaver said similar compound dynamics appeared in the Russian heat wave of 2010 and the Australian bushfires of 2019–20.
“What this study shows is that warming doesn’t just make heat waves more likely — it changes how heat and drought interact, amplifying the risks we face,” Weaver said.
Outlook
The study covered events through 2023. The authors said the 10-year average for heat-first drought coverage has likely climbed since then, given 2024’s record global heat and a 2025 that was nearly as warm. Some computer models, they noted, forecast another major El Niño developing later this year, which could push that average higher still.