Human activity likely triggers extreme heat waves, study says

A new study by the Chinese Academy of Sciences found that greenhouse gases increase the probability of heat waves, making these extreme weather events more frequent and worse.

The study, published Friday in the Advance in Atmospheric Sciences, follows analysis on the 2021 North American heat wave that had a significant impact in British Columbia where 595 people and over one billion marine animals died. Temperatures averaged around 30 C, but the highest temperature recorded was in B.C. at 49.5 C, breaking Canada’s all-time heat record.

Researchers focused on atmospheric circulation patterns, which is how air flows and affects surface air temperatures around the planet.

In their data, they found three atmospheric circulation patterns that occurred simultaneously during the 2021 heat wave. However, co-occurring atmospheric patterns are not new and they have not previously been known to trigger heat waves. Ultimately, the researchers concluded human activity through greenhouse gases likely made the atmospheric circulation patterns worse and provoked a heat wave.

“We found that it is likely that global warming associated with greenhouse gases influences these three atmospheric circulation pattern variabilities, which, in turn, led to a more extreme heatwave event,” Chunzai Wang, lead author of the study said in a news release

While the study included a stark reminder for immediate climate action before these extreme events become more frequent, another extreme heat wave is currently gripping parts of the Northern hemisphere.

Canada, Europe and the U.S. have all experienced high temperatures for the past week as Europe suffers the brunt of the heat wave with temperatures reaching 40.3 C. Wildfires have forced hundreds of people to leave their homes in Greece, while officials in Portugal have reported over 1,000 sudden deaths blamed on the heat wave.

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Francis Zwiers, CEO of the Pacific Climate Impacts Consortium, says climatologists who have been closely following these extreme climate patterns have also found greenhouse gases to be one of the main catalysts for the rise in global temperatures.

“The evidence supports that what's happening is a consequence of rising greenhouse gas concentrations. So we're seeing that happen in Canada and that's raising the risk of extreme warm temperatures everywhere,” Francis Zwiers told CTV News Channel on Saturday.

While extreme heat events are not new, Zwiers says the frequency at which they occur is concerning.

“Between the 1850s and 1900s, an event that we estimated would have happened once every 10 years is now happening once every three or three and a half years,” he said.