Climate scientists say recent heat waves in Canada were made much more likely by human-caused climate change.
Environment and Climate Change Canada recently analyzed 12 of the hottest Canadian heat waves from July and August.
Dr. Nathan Gillett, a research scientist with the federal agency, said Atlantic Canada saw the country’s most extreme event in August.
“On August the 13th, the temperatures there were made far more likely by human-induced climate change, or in other words, at least 10 times more likely by human-induced climate change,” Gillett told reporters on Wednesday.
Eleven other heat waves analyzed by climate scientists were at least two times more likely due to human-caused climate change, said Gillett.
Environment Canada uses climate models to compare today’s climate to a pre-industrial one and demonstrate how greenhouse gases and other human influences impact the chances of some extreme weather events.
Dubbed the Rapid Extreme Weather Event Attribution system, it showed that the heat waves experienced during July and August would have been rare in a pre-industrial climate.
Scientists only analyzed heat waves when the temperature exceeded the typical hottest day of the year for that region. In some regions, including Ontario, Manitoba and Saskatchewan, the temperatures did not exceed that threshold.
“If we look at the summer as a whole, we see that it was the 11th warmest summer on record. So it wasn’t exceptional, but it was still certainly warmer than average in a record stretching back to 1948,” said Gillett.
Heat impacted everyone differently
Jennifer Smith, the national warning preparedness meteorologist with the agency’s Meteorological Service of Canada, said while heat touched every part of Canada this summer, it did not all happen at once.
“Some regions saw early-season surges. Others faced long, persistent stretches. And in some areas, it was the overnight warmth that made the heat feel most oppressive,” she said.
“In some places, it was the drier-than-normal conditions that allowed temperatures to reach higher-than-normal values.”
That was especially prevalent in the Maritimes, where Smith said much of the heat was packed into a narrow window between early July and August, giving some the sense of a short summer.
Manitoba and northwestern Ontario saw the country’s first heat wave in early May, and the longest heat event was in northern British Columbia and lasted nearly three weeks.
“Heat is one of Canada’s deadliest weather hazards. Even just a few days of extreme heat can put real pressure on health systems, increase wildfire risk, and affect the daily rhythm of life,” Smith added.
“This summer reminded us that it’s not just about daytime highs. The duration of heat events and warm nights made them especially dangerous.”
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