The report says that without climate change, a heat wave is “nearly impossible”
New data shows that the recent heat wave in the Pacific Northwest-which has overwhelmed communities in Canada and the United States-is at least 150 times more likely to occur due to climate change.
A team of 27 researchers from the World Weather Attribution Initiative, including scientists from universities and meteorological institutions in North America and Europe, studied observations and computer simulations to compare today’s climate with past climates.
They concluded that without human influence, a record-breaking heat wave would be “almost impossible”.
Lytton, BC, a small village in Fraser Canyon, went bankrupt Record the hottest temperature It was recorded in Canada for three consecutive days during the heat wave and finally reached 49.6 C. This is higher than 45 C, recorded in Saskatchewan in 1937.
Faron Anslow, a climatologist at Victoria Pacific University, said: “When we look at temperature records over time, the hottest temperature of the year is steadily rising, but then this event happened. It just broke the record, the Climate Impact Alliance and the co-author of the report, which was released on Wednesday.
“Literally, the data points are drawn in a certain way, and we have to circle them to get people’s attention because the eyes don’t expect them to be there,” Anslow told CBC News.
“What we have seen is unprecedented,” said co-author Frederick Otto, a climate scientist at Oxford University, in a statement. “You shouldn’t break the record of four or five degrees Celsius.”
The report has not been peer-reviewed, but the scientists plan to submit it to the journal in the near future.
Although climate change makes such extreme heat waves more likely, scientists say it is still very unusual.
They estimate that such events in today’s climate—about 1.2 degrees Celsius higher than before the industrial revolution—should occur every 1,000 years.
But if the temperature rises by 2 degrees Celsius, this may happen in 2050, and researchers say that heat waves like this may happen at least once or twice every ten years.
The team offered two possible explanations for how a heat wave of this scale occurred.
First, they said that the pre-existing drought and the abnormal atmospheric conditions that caused the “hot dome”, coupled with climate change, have caused very high temperatures. If there is no climate change, the peak temperature will drop by about 2 degrees Celsius.
The second explanation is that the Earth’s climate has exceeded a threshold, that is, a relatively small temperature change of 1.2 degrees Celsius will cause the extreme temperature to rise faster than the model predicts.
Anslow said that it is difficult to pinpoint the cause. The record high was set a full month before the usually hottest time of the year.
“This means that if this incident happened later, it might be a little hotter,” Anslow said. “Moreover, this incident happened shortly after the longest day of the year […] You only have these extra hours and minutes to let the sun’s energy drop and bake the landscape. “
Last year, a heat wave in Siberia triggered wildfires and melted permafrost with temperatures as high as 38 degrees Celsius. The World Weather Attribution Initiative published a report stating that climate change has increased the likelihood of this event by at least 600 times.
Stewart Cohen, a retired climatologist who was not involved in the report, warned that it came out “soon” and should be considered a “quick exercise.”
But, he said, its results support what other scientists have quickly learned—Canada’s strategy for coping with high temperatures is worth looking at again.
“This is just another piece of evidence that shows the urgency of reassessing how we manage extreme events,” Cohen said.