North America's Extreme Heatwave "Virtually Impossible" Without Climate Change


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

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Canada set a record temperature of 47.9°C (118°F) on June 28 in the village of Lytton, which later burned down due to rampant wildfires. Image credit: Nelson Antoine/

Make no mistake, the recent heatwave that hit the Pacific Northwest was only made possible thanks to climate change, according to climate scientists. 

A new analysis of the heatwave that baked the US and Canada over the last days of June 2021 has found that these soaring temperatures would be “virtually impossible” to achieve without human-caused climate change.


Their findings suggest that this heatwave would be at least 150 times rarer without human-induced climate change. Furthermore, this heatwave was about 2°C (3.6°F) hotter than it would have been if it had occurred at the beginning of the Industrial Revolution.

“The observed temperatures were so extreme that they lie far outside the range of historically observed temperatures. This makes it hard to quantify with confidence how rare the event was,” the report reads. 

“In the most realistic statistical analysis the event is estimated to be about a 1 in 1,000-year event in today’s climate.”

The findings come from an international team of 27 climate researchers working under the umbrella of the World Weather Attribution network who analyzed the data in just a matter of days. The research has not yet been peer-reviewed, given this very short window of time. 


Multiple cities in Oregon and Washington, as well as the western provinces of Canada, recorded temperatures far above 40ºC (104ºF) towards the end of June. Canada set a record temperature of 47.9°C (118°F) on June 28 in the village of Lytton, which later burned down due to rampant wildfires.

News reports indicate that there was an increase in emergency calls, emergency department visits, and deaths linked to the heatwave. British Columbia reported 486 "sudden and unexpected" deaths between June 25-30, which the coroner's office has stated though it's too early to confirm, are likely "attributable to the extreme weather". The full data on the fatalities caused by the heatwave won’t be available for three to six months in Canada and a year in the US, but early estimates suggest the heat caused “at least several hundreds of extra deaths,” according to the report. 

It was previously claimed no single extreme weather event can be attributed to human-caused climate change, that it's more a general trend. However, this is no longer true, scientists say. Hundreds of peer-reviewed studies have now provided evidence of how climate change is directly responsible for extreme weather events, including one released earlier this week that linked human-caused global warming and an increase in extreme precipitation events. It’s also become increasingly clear that climate change will make heatwaves longer, larger, hotter, and more frequent.

This new analysis also shows how the recent event in the Pacific Northwest would be even more intense if the climate crisis continues unchecked. Currently, global average temperatures are 1.2°C (2.16°F) above pre-industrial levels. If global temperatures creep up to 2°C above pre-industrial levels, which at current emission levels could be reached as early as the 2040s, this heatwave would have been another 1°C hotter. In a world with 2°C of global warming, extreme heatwaves like this would also occur roughly every five to 10 years. 


Buckle up, it’s not going to be a comfortable ride.

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