Is the mild spell experienced by Quebec in the last few days linked to climate change? The question no longer arises, the experts agree. Temperature anomalies – for heat-related events, at least – today are almost all driven by human activity.
Many heat records were recorded across the province for New Year’s Eve. From Gatineau to Fermont, via Baie-James, Val-d’Or, Montreal and Roberval, temperatures peaked on December 30 and 31.
• Read also: Winter heat records broken in Europe and Quebec…but polar cold in the United States and India
You should know that the Quebec winter has always been punctuated by periods of mildness and polar cold, even without the influence of human activity. Given this natural climate variability, how do we know if temperature anomalies are really due to climate change?
It’s (much) warmer
“Rather than asking if the mild spell that we have just experienced in Quebec is attributable to climate change, we should rather say that this mild spell is totally consistent with global warming and that it is part of a major trend that is not going in the right direction,” asserts the general manager of Ouranos, Alain Bourque.
“Without climate change, there would be as many thaws as cold spells, which would give a constant global temperature for the last 150 years,” adds the climatologist.
However, Quebec has only experienced positive temperature anomalies since 1998, according to data from the Ministry of the Environment. The annual average for the past 24 years has therefore always been higher than normal in the 20e century, unlike previous years when the gap varied from plus to minus.
“When we look at the whole planet, we see that heat waves are much more frequent and probable than episodes of extreme cold”, specifies the meteorologist at Environment Canada, Nicolas Gillett.
In fact, Europe was not left out for the New Year. From France to western Russia, the temperature soared to 20 degrees above normal between December 31 and the 2 January.
“More likely or more serious” events
In the early 2000s, a new area of research in climatology emerged: the science of attribution, which explores the influence of humans on weather phenomena such as heat waves, floods, typhoons, droughts and forest fires.
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A satellite dish is used to take children across a flooded area after heavy monsoon rains in Pakistan, August 26, 2022.
Experts find that the vast majority are “more likely or more severe” due to climate change.
A Carbon Brief report published last August analyzed 504 events that have occurred in recent years. Results: 71% of were aggravated by human activity. And of the 152 heat episodes studied, climate change increased the likelihood or severity of 93% of them.
Twelve extreme weather events, such as heat waves in the UK, India and Pakistan, would even have been ‘impossible’ without the climate crisis.
• Read also: Extreme heat: UK issues first-ever red alert
The same goes for the heat dome that hit British Columbia in 2021, recalls meteorologist Nicolas Gillett. “It has been proven that it would have been almost impossible without the influence of human activity,” he says.
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Multiple fires broke out in British Columbia after the heat dome that set new temperature records, at the end of June 2021.
• Read also: Canada’s heat dome ‘almost’ impossible without global warming
“Historically, it was the natural variability of the climate that predominated to explain these events. In 30 years, they will be entirely explained by climate change,” warns Alain Bourque.
And today? “We have exceeded the threshold of detectability, that is to say that people have started to realize for themselves that the climate is no longer the same, and we can clearly attribute all this to human activity”, he argues.