What’s new in this study
Global warming is making dangerously hot weather more common and extreme across continents. A new study by British researchers takes a unique approach to identifying where the risk is greatest.
When mercury levels spike, communities can suffer for a number of reasons: because no one checks on elderly people living alone, because poor people don’t have air conditioning, because workers have no choice but to toil outdoors. The new study focuses on one simple reason why societies may be especially vulnerable to extreme heat waves: because they haven’t experienced them before.
Whether it’s heat, floods, or disease epidemics, societies are often only coping with the worst disasters they’ve experienced in recent memory. Dann Mitchell, a climate scientist at the University of Bristol in the United Kingdom and one of the authors of the study, said that in the aftermath of a disaster, people and policymakers are very aware of the risks and how to respond. “And then, as the years go by, you kind of forget and it doesn’t bother you so much,” he said.
Dr. Mitchell and his colleagues looked at the maximum daily temperatures around the world between 1959 and 2021. They found that an area covering 31 percent of the Earth’s land surface experienced such unusually high temperatures that it statistically shouldn’t have happened. The research suggests that these places are now somewhat prepared for the intense heat ahead.
But there are still many areas that have not experienced such extreme heat, purely by chance. So they may not be ready.
According to the study, these areas include economically developed regions such as Germany, the Netherlands, Belgium, and Luxembourg, as well as areas around Beijing in China. But they also include developing countries such as Afghanistan, Guatemala, Honduras and Papua New Guinea, which are more likely to lack the resources to keep their people safe.
Other particularly dangerous areas include the Russian Far East, northwestern Argentina and parts of northeastern Australia.
The study was published Tuesday in the journal Nature Communications.
why is this important
In 2021, a heat wave in the Pacific Northwest smashed local records by astonishing magnitude. Hundreds of people may have died from the heat in Washington and Oregon. The crops withered. Wildfire devastates the village of Lytton, British Columbia.
New research shows that over the past few decades, periods of higher temperatures than are statistically plausible have occurred around the world. That suggests they could happen again anywhere, though not all of them are as unexpected as the most recent one in the Pacific Northwest.
Human-caused climate change won’t help. As the planet warms, the range of temperatures that many places may experience is shifting upwards. Scorching weather once seen as unusual is becoming more likely.
But the weather is always highly variable, and the most idiosyncratic events are those that, by definition, people experience infrequently. Karen A. McKinnon, an assistant professor of statistics and the environment at UCLA, said society should be “humble” about all possible climate extremes.
“We’re often not even prepared for this baseline level of variability,” said Dr. McKinnon, who was not involved in the new study.
understand the big picture
The study only focused on maximum temperatures, which aren’t the only thing that makes heat waves destructive. Humidity is also important, as is muggy temperatures at night, which removes the opportunity for people to cool off from muggy daytime conditions.
In general, it is more difficult for the poor to obtain heat protection—for example, in the form of green or air-conditioned spaces—than the rich.
Even in places that have already experienced record-breaking heat waves, many residents may still be unprepared for future extremes as average conditions remain largely mild. In research published last year, Dr McKinnon showed that in the Pacific Northwest, high summer temperatures occur more frequently than might be expected given the region’s generally mild climate.