Residents of a nursing home in Bordeaux, France received water during a heatwave in June. Photo Thibaud Moritz / Agence France-Presse – Getty Images
Western Europeans have experienced more than their fair share of heat waves in recent years, with frequent bouts of scorching and potentially deadly weather almost every summer.
This year, parts of the region also suffered from intense heat before the summer began.
A new study confirms that Western Europe has become what researchers call a access point of heat waves over the past four decades, with events that increased frequency and cumulative intensity (defined as heat exceeding a certain threshold).
A man refreshes himself in a fountain in central Madrid, Spain on Saturday, June 18, 2022. AP Photo / Manu Fernández)
Furthermore, the study found that changes in frequency and intensity are happening more rapidly in Europe than in many other parts of the world, including another hotspot, the western United States.
Global warming has contributed to aggravating heat waves everywhere, for the fundamental reason that they start from a reference temperature higher than ever.
Global average temperatures have risen by about 1.1 degrees Celsius (about 2 degrees Fahrenheit) from the late 19th century, when diffuse emissions of heat-trapping carbon dioxide began.
But the study, released this week in Nature communicationshas found another mechanism, that relating to atmospheric circulationwhich contributed to the acceleration of the heat wave in Western Europe.
Specifically, the researchers found a link between heat waves and the state of the jet stream, the river of fast west-to-east winds in the upper atmosphere in mid-latitudes.
Sometimes the jet stream splits in two.
Heat waves can develop in areas with low winds and high pressure air, known as block peaks, between the northern and southern flanks of the jet stream.
The researchers found that these cases of “double jets“have increased in frequency and last longer, and that these changes explain the changes in heat waves.
Efi Rousi, a senior scientist at the Potsdam Climate Research Institute in Germany and lead author of the study, said it wasn’t clear what was causing the jet stream to split.
The block maxima could develop on their own and cause the jet stream to split, he said, “or it could be the opposite, the jet stream splits for other reasons, and this allows the block to develop.
“We don’t know exactly what the trigger is,” added Rousi.
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Enrico Fontana
Source: Clarin
