Damian Carrington
More heatwaves even worse than those seen recently in north-west of America forecast in research
Firefighters tackle the Bootleg fire, near Klamath Falls, Oregon on 17 July. Scientists say the world has yet to see the worst impacts possible from global heating. Photograph: US Forest Service/AFP/Getty Images
“Record-shattering” heatwaves, even worse than the one that recently hit north-west America, are set to become much more likely in future, according to research. The study is a stark new warning on the rapidly escalating risks the climate emergency poses to lives.
The shocking temperature extremes suffered in the Pacific north-west and in Australia 2019-2020 were “exactly what we are talking about”, said the scientists. But they said the world had yet to see anything close to the worst impacts possible, even under the global heating that had already happened.
The research found that highly populated regions in North America, Europe and China were where the record-shattering extremes are most likely to occur. One illustrative heatwave produced by the computer models used in the study showed some locations in mid-northern America having temperatures 18C higher than average.
Preparing for such unprecedented extremes was vital, said the scientists, because they could cause thousands of premature deaths, and measures taken to adapt to date had often been based only on previous heat records.
Scientists already know that heatwaves of the kind mostly seen today will become more common as the climate crisis unfolds. But heatwaves are usually analysed by comparing them with the past, which means the vast majority are only marginally hotter than before. This can give a false sense of a gradual rise in record temperatures.
The new computing modelling study instead looked for the first time at the highest margins by which week-long heatwave records could be broken in future.
It found that heatwaves that smash previous records by roughly 5C would become two to seven times more likely in the next three decades and three to 21 times more likely from 2051–2080, unless carbon emissions are immediately slashed. Such extreme heatwaves are all but impossible without global heating.
Soldiers inspect damage after the flooding of the River Ahr, in Rech in the district of Ahrweiler, Germany, on 21 July. Photograph: Friedemann Vogel/EPA
The vulnerability of North America, Europe and China was striking, said Erich Fischer, at ETH Zurich in Switzerland, who led the research. “Here we see the largest jumps in record-shattering events. This is really quite worrying,” he added.
“Many places have by far not seen anything close to what’s possible, even in present-day conditions, because only looking at the past record is really dangerous.”
The study also showed that record-shattering events could come in sharp bursts, rather than gradually becoming more frequent. “That is really concerning,” Fischer said: “Planning for heatwaves that get 0.1C more intense every two or three years would still be very worrying, but it would be much easier to prepare for.”