Global warming today reveals a worrying phenomenon: entire regions are experiencing heatwaves so intense that they defy the predictions of current climate models. These extreme anomalies, detected everywhere except Antarctica, are redefining the boundaries of our understanding of the climate.
Between 2016 and 2023, heat records were broken at an alarming pace. 2023 was the hottest year ever recorded, and 2024 seems poised to follow this trend. However, these average increases mask a more localized reality: regions such as Northwestern Europe or Central Asia are facing heatwaves of extraordinary intensity, killing thousands of people, destroying crops, and triggering devastating wildfires.
Regions where observed heatwaves exceed climate model trends.
- The areas outlined with the darkest red colors are the most extreme.
- The lighter reds and oranges exceed model predictions, but not as dramatically.
- The yellows are approximately aligned with the models, while the greens and blues are below what the models project.
Credit: Adapted from Kornhuber et al., PNAS 2024 A recent study published in
PNAS establishes a global map of climate "hotspots." Among the hardest-hit areas is Western Europe, where repeated heatwaves caused 60,000 deaths in 2022, followed by 47,000 in 2023. These episodes, often twice as intense as average trends, highlight structural inadequacies, such as the lack of air conditioning in historically temperate countries.
In North America, the most notable example remains the June 2021 heatwave in the Northwestern United States and Southwestern Canada. Temperatures, reaching up to 54°F (30°C) above averages, literally burned towns like Lytton in British Columbia to the ground. Researchers attribute these extreme phenomena to unusual oscillations in the jet stream, exacerbated by the accelerated warming of the Arctic.
However, the jet stream does not explain everything. According to the study, combined factors such as smaller atmospheric waves or reduced soil moisture due to rising temperatures also contribute to these anomalies. The convergence of these parameters creates what scientists call "grey swan events": rare, but not entirely unpredictable situations.
These heatwaves, though localized, have global repercussions. The most vulnerable areas, such as central China or southern Africa, are already experiencing irreversible damage to agriculture and infrastructure. In these regions, the capacity to adapt remains low in the face of temperatures regularly exceeding forecasts.
Finally, researchers are calling for increased vigilance. Heatwaves, which already kill more people than any other combined meteorological phenomenon, require official recognition. The idea of naming these heatwaves, as is done for hurricanes, has been proposed to raise public awareness and strengthen preparedness.