“Unmistakably” climate change: Current heat virtually impossible 50 years ago

The current heatwave in Europe is “unmistakably” caused by climate change, research collective World Weather Attribution (WWA) concluded in an analysis in which researchers from the KNMI also participated. According to the researchers, the current temperatures would have been virtually impossible 50 years ago.

The scientists compared the current heatwave to the situation in 1976, when heat records were set in several European countries. They also looked at the first major heatwave of this century in 2003.

Fifty years ago, it was virtually impossible for temperatures in June to rise as high as they are now. During a comparable heatwave back then, it would have been about 3.5 degrees cooler during the day, they calculated by overlaying the current heat intensity onto the climate of 1976. The world was an estimated 1.1 degrees cooler at the time.

Compared to 2003, daytime temperatures like those of today have become ten times more likely. And the sweltering night temperatures keeping many people awake this week are nowadays over 100 times more likely than during “the infamous heatwave” of 23 years ago, according to the scientists.

"The weather pattern itself is not particularly unusual, but the temperatures are," said German climate scientist Friederike Otto in a commentary. Due to climate change, partly caused by the emission of fossil fuels, heatwaves are warmer, last longer, and occur more frequently, the report said. According to the scientists, the El Niño weather phenomenon plays no role in the current extreme temperatures.

In the past week, nearly half of the 854 European cities whose temperatures the researchers monitored reached the highest “heat stress level” ever, or are expected to do so soon. A large proportion of those cities are located in Northern, Western, and Central Europe, including the Netherlands, England, and Germany.

“Many people live, work, and study in places that are not built for the temperatures we are currently facing,” said co-author Caroline Pereira Marghidan, a climate risk expert at the Red Cross and a researcher at the KNMI. “As temperatures continue to rise, we are seeing a growing gap between the pace of climate change and the pace of adaptation.”

On Thursday, United Nations climate chief Simon Stiell also linked the current extreme temperatures in Europe to climate change.