December 8, 2022

The 2021 western North American heatwave was among the most extreme events ever recorded

Heat warnings in western US and Canada as wildfires burn


The western United States and Canada are in the grips of another dangerous heatwave – Copyright AFP/File STR

The 2021 heatwave that scorched western North America last June was among the most extreme ever recorded globally, new modeling and analysis by researchers at universities in the United Kingdom shows.

The research, led by the University of Bristol, was published Wednesday in the journal Science Advances, and shows heatwaves are projected to get hotter in the future as climate change worsens.

In looking at the June 2021 heatwave in Western North America, the researchers used a novel assessment of heat extremes, meaning they investigated how extreme the event was in the global context, as well as looking at the events based on how far outside their natural variability the events were.

The researchers found five other heat waves that were more extreme since 1960, however, they were actually underreported. The western North America heatwave last summer was record-breaking with an all-time Canadian high of 49.6 °C (121.28°F) in Lytton, British Columbia, on June 29, an increase of 4.6 °C from the previous peak.

B.C.’s coroner attributed nearly 600 deaths to the heat from mid-June to August, with 526 deaths in just one week between June 25 and July 1.

https://www.youtube.com/watch?v=HulxxPkk6DQ

The paper shows that extremes are getting hotter as temperatures rise with climate change, said Vikki Thompson, senior research associate at the School of Geographical Sciences and Cabot Institute for the Environment at the University of Bristol, reports Global News.

CTV News Canada is reporting that the study projects that by around 2080, heatwaves like the one last summer could have a one-in-six chance of happening every year in western North America as the effects of human-caused climate change worsen.

Thompson said in an interview Wednesday: “We do also include the lower emissions scenarios in our extra data so people can see if policies do change, where we could be instead.”

“And that’s a much better picture, it would still be a one-in-1,000-year event by the end of the century, if emissions were reduced.”

To better understand the heatwave in a global context, the researchers examined 230 regions around the world, including B.C. and Alberta. They then compared the single hottest day in each region all year with the average over the hottest three months annually over the previous decade, Thompson said.

A combination of high atmospheric pressure and drought conditions in much of western North America helped drive the heatwave, the study says. Additionally, to gain further insight into future heatwaves, the researchers used Earth systems modeling that projected events of similar intensity in the same area.