Heat waves that spark damaging droughts are happening more frequently, study finds

WASHINGTON (AP) — Heat waves that bring sudden, devastating drought are spreading across the world at an accelerating pace, underscoring how extremes fueled by climate change can dangerously pile on top of each other, a new study finds.

Researchers in South Korea and Australia studied extreme weather – a combination of heat and drought – and found that it increased as the world warmed. But what increases particularly quickly is the most damaging type when heat arrives first and triggers drought. In the 1980s, this type of extreme only covered about 2.5% of the land surface each year. In 2023, the latest year the researchers studied, that figure rose to 16.7%, with a 10-year average of 7.9%.

The average likely increased even more with record global heat in 2024 and a nearly as hot 2025, according to the study authors.

In their study published Friday in Science Advances, the scientists say the acceleration of change is even more concerning than the raw numbers. In the first two decades or so since 1980, the spread of extreme temperatures increased, but the rate over the past 22 years is eight times higher than the previous rate, the study found.

Events where drought occurs first, followed by extreme heat, remain more frequent and are also increasing. But researchers focused on the growing number of cases where heat struck first. Indeed, when heat hits first, droughts are stronger than when they occur first or are not accompanied by high heat, said co-author Sang-Wook Yeh, a climate scientist at Hanyang University in South Korea.

They also lead to “flash droughts,” which are more damaging than ordinary droughts because they occur suddenly, leaving people and farmers unable to prepare, said lead author Yong-Jun Kim, a climatologist in Hanyang.

Flash droughts – when hot air gets thirstier, it sucks up more water from the ground – have increased in a warming world, previous studies have found.

“The study illustrates a key point about climate change: the most damaging impacts often come from compound extremes. When heatwaves, droughts and wildfire risks occur together – as we saw in events like the 2010 Russian heatwave or the Australian bushfires in 2019-2020 – impacts can intensify quickly,” said Andrew Weaver, a climate scientist at the University of Victoria in British Columbia, Canada. “This study shows that warming not only makes heat waves more likely, but it changes the way heat and drought interact, amplifying the risks we face.”

Weaver wasn’t part of the study, but he lives in the Pacific Northwest, where the 2021 heat dome and drought was what Kim called a prime example of what they see increasing rapidly. Others include 2022 heat and drought around China’s Yangtze River and 2023-24 record heat and drought in the Amazon, Kim said.

“The 2021 Pacific Northwest heat dome illustrates how quickly these compound extremes can escalate: temperatures near 50°C (122 degrees Fahrenheit) in Lytton, British Columbia, were followed by rapid drying and extreme wildfire conditions that destroyed the community,” Weaver, a former Canadian lawmaker, said in an email.

The study found that the largest increases in heat-related droughts occurred in South America, western Canada, Alaska and the western United States, as well as parts of central and eastern Africa.

Kim and Yeh said they noticed a “change point” around the year 2000, when everything accelerated between hot and then drought situations.

Jennifer Francis, a climate scientist at the Woodwell Climate Research Center who was not involved in the study, said this point of change “eerily coincided with the onset of rapid Arctic warming, the loss of sea ice, and the decline of spring snow cover on the continents of the Northern Hemisphere.”

In addition to long-term warming causing more compound extremes, Kim said he saw an acceleration in how heat passed from land to air and back just before that 2000 change point. He and Yeh hypothesized that Earth might have crossed a “tipping point” where the change would be irreversible.

Several aspects of Earth’s climate and ecological systems changed in the late 1990s, possibly triggered by a major El Nino event in 1997-98, said Gerald Meehl, a climatologist at the National Center for Atmospheric Research who was not involved in the study. But he added that it’s hard to say whether these are permanent changes.

Some computer models predict another major El Nino – a natural warming of parts of the Pacific that would distort the global climate – is brewing later this year.

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