Human activities are fueling more extreme heatwaves

According to climate experts, the current heatwave in the UK is just a taste of things to come. They predict that 40-degree Celsius days will be the norm by 2050. 

In a new study from the Chinese Academy of Sciences, experts report that human-caused emissions are at least partially to blame for last year’s temperature spike in the US and Canada that killed 1,500 people. 

“An extraordinary and unprecedented heatwave swept western North America in late June of 2021, resulting in hundreds of deaths and a massive die-off of sea creatures off the coast as well as horrific wildfires,” said study co-author Chunzai Wang.

Moreover, this link may explain the current heatwave in the UK. Greenhouse gas emissions and atmospheric patterns seem to be the primary culprits. 

“In this paper, we studied the physical processes of internal variability, such as atmospheric circulation patterns, and external forcing, such as anthropogenic greenhouse gases,” said Wang. 

Using computer models, the researchers found three circulation patterns that coincided during the 2021 heatwave: the North Pacific, the Arctic-Pacific Canada, and the North America pattern.

“The North Pacific pattern and the Arctic-Pacific Canada pattern co-occurred with the development and mature phases of the heatwave, whereas the North America pattern coincided with the decaying and eastward movements of the heatwave,” Wang said. “This suggests the heatwave originated from the North Pacific and the Arctic, while the North America pattern ushered the heatwave out.”

Although air patterns often co-occur without triggering intense heatwaves, the experts found human greenhouse emissions played a significant role in causing last year’s heatwaves.

Based on model simulations, the researchers are confident that the number of severe heatwaves will increase by more than 30 percent, and greenhouse gases will cause nearly two-thirds of that increase. 

“From the CMIP6 models, 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,” explained Wang. 

“If appropriate measures are not taken, the occurrence probability of extreme heatwaves will increase and further impact the ecological balance, as well as sustainable social and economic development.”

The study is published in the journal Advances in Atmospheric Sciences,

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By Erin Moody , Earth.com Staff Writer