The heat waves simultaneously broiling the southwest United States and southern Europe would have been “virtually impossible” if not for climate change, according to a group of scientists who study the probability of extreme weather events.
A third heat wave, in China, could have been expected about once every 250 years if global warming weren’t a factor.
“The role of climate change is absolutely overwhelming” in producing all three extremes, said Friederike Otto, a climate scientist at Imperial College London, who contributed to the new research, which was published Tuesday by the World Weather Attribution group.
The group is a loose consortium of climate scientists who study extreme weather and publish rapid findings about climate change’s role in major events. Their research methods are published and peer-reviewed, but this specific, rapid analysis has not yet undergone a typical academic review process. Previous analyses by this group have held up to scrutiny after their initial release and were ultimately published in major academic journals.
Global warming has increased the likelihood of extreme temperatures so significantly that heat waves as powerful as the ones setting records in places like Phoenix, Catalonia and in China’s Xinjiang region this July could be expected once every 15 years in the U.S., once every 10 in southern Europe and once every five in China, the research found.
“This is not a surprise. This is absolutely not a surprise in terms of the temperatures, the weather events that we are seeing,” Otto said at a news conference. “In the past, these events would have been extremely rare.”