Global warming is making dangerously hot weather more frequent and extreme on every continent. A new study by researchers in Britain takes a unique approach to identifying places most at risk.
When the mercury peaks, communities can suffer for many reasons: because no one checks in with elderly people living alone, because poorer people don’t have air conditioning, because workers don’t have much choice but to toil outside. The new study focuses on one simple reason why societies may be particularly vulnerable to an extreme heat wave: because they’ve never experienced one.
Whether it’s heat, floods or disease epidemics, societies are generally equipped to deal with only the worst disasters they’ve seen in recent memory. Immediately after a disaster, people and policymakers are very aware of the risks and how to respond, said Dann Mitchell, a climate scientist at the University of Bristol in England and author of the study. “And then as the years go by, you kind of forget about it and it doesn’t bother you as much,” he said.
Dr. Mitchell and his colleagues looked at maximum daily temperatures around the world between 1959 and 2021. They found that regions covering 31 percent of the Earth’s surface were so extraordinarily hot that statistically it shouldn’t have happened. These places, the study argues, are now prepared to some degree for future severe hot spells.
But there are still many areas that, simply by chance, have not yet experienced such extreme heat. So maybe they are not that prepared.
According to the study, these are economically developed places such as Germany, the Netherlands, Belgium and Luxembourg, plus the region of China around Beijing. But they also include developing countries such as Afghanistan, Guatemala, Honduras and Papua New Guinea, which probably lack the resources to protect people.
Other areas at risk include far eastern Russia, northwestern Argentina and part of northeastern Australia.
The study was published Tuesday in the journal Nature Communications.
Why this is important
In 2021, a heat wave in the Pacific Northwest shattered local records by staggering margins. Hundreds of people in Washington and Oregon may have died from the heat. Crops shriveled. Wildfire destroyed the village of Lytton, British Columbia.
The new study shows that hot spells beyond the range of statistical plausibility have occurred all over the world in recent decades. This suggests they could happen again anywhere, though not all of them will be as unusual as the recent Pacific Northwest.
Man-made climate change is not helping. As the planet warms, the range of possible temperatures that many places can experience shifts upward. Scorching heat that would once have counted as unusual is increasingly likely.
But the weather has always been very changeable, and the most special events are those that people don’t often experience by definition. Societies should remain “humble” about any climatic extremes that may occur, said Karen A. McKinnon, an assistant professor of statistics and the environment at the University of California, Los Angeles.
“We are often not even prepared for that basic level of variability,” said Dr. McKinnon, who was not involved in the new study.
Understand the bigger picture
The study only looks at maximum temperatures, which are not the only factor that can make heat waves devastating. Humidity is also important, as are sweltering nighttime temperatures, which deprive people of the ability to cool down from oppressive daytime conditions.
In general, relief from heat – in the form of greenery or air-conditioned spaces, for example – is less accessible to the poor than to the rich.
Even in places that have already experienced record-breaking heat waves, many residents are still unable to prepare for future extremes as average conditions remain largely subdued. In research published last year, Dr. McKinnon noted that very high summer temperatures are more common in the Pacific Northwest than would be expected given the region’s generally mild climate.