Climate change boosts wildfires in Canada – 08/22/2023 – Environment

Months of hot, dry weather created the conditions for this year’s record spate of wildfires in Canada, prompting scientists to point the finger at climate change.

An extensive study, published this Tuesday (22), now supports this assertion, by demonstrating that fire seasons of this intensity are at least seven times more likely to occur as a result of the burning of fossil fuels.

The study, carried out by the academic collaboration group World Weather Attribution, also found that over the course of the year, conditions conducive to the occurrence of fires were 50 times more intense due to global warming.

“As we continue to warm the planet, these types of events will become more and more frequent and more intense,” Clair Barnes, an environmental statistician at Imperial College London and lead author of the study, told AFP.

Canada is suffering from the most devastating wildfire wave on record, resulting from record high temperatures, low humidity and early melting snow. Some 15.3 million hectares were burned, an area larger than Greece and more than double the previous record set in 1989.

About 200,000 people were evacuated, at least four died, and smoke from the burning forests resulted in the spread of dangerous air pollution across much of Canada and the southern United States, leading to spikes in calls for emergency services and even the closing of schools.

By the end of July, forest fires had directly emitted more than a billion tons of carbon dioxide (CO_two) in the atmosphere, as well as methane and nitrous oxide, which had an additional equivalent combined greenhouse effect of 110 million tons of CO_twoaccording to a recent survey.

In the current study, the scientists analyzed the province of Quebec, in eastern Canada, looking at zones with similar climate and vegetation. The region recorded an exceptionally high number of fires in May and June, when temperature records were broken by 0.8°C.

Because wildfires are so complex and not driven solely by weather, scientists focused on fire-friendly conditions using a metric called the Fire Weather Index (FWI).

The index combines temperature, wind speed, humidity and precipitation. The research team compiled this data from January through July to produce a measure of the severity of meteorological fire risk for the entire season.

While the fires in Quebec were unprecedented, analyzes of recent climate records have indicated that the seasonal conditions that cause fires are no longer exceptional, occurring once every 25 years. This means that they now have a 4% risk of occurring each year.

To understand the contribution of human-caused global warming, the researchers used computer model simulations to compare the climate as it is today, after about 1.2°C of global warming since the late 1800s, to the climate of the past.

This analysis demonstrated that climate change has made seasons of this severity at least seven times more likely to occur compared to the pre-industrial era. Barnes reinforced, however, that this is a timid estimate, since scientists prefer to be conservative due to statistical uncertainty.

Indigenous communities, the hardest hit

Yan Boulanger, an ecologist at the Canadian Forest Service and second author of the study, told AFP that the cumulative impact of circumstances favorable to the fire was decisive. “These fires got so big because these fire-prone weather conditions lasted too long.”

The team also identified the length of days these fire-prone weather conditions peaked, and found that these peak conditions were more than twice as likely to occur than in the past due to climate change.

If the world continues to burn fossil fuels at high rates, the probability and intensity of the occurrence of weather conditions prone to severe fires will only increase, reinforces the study.

The fires put the forestry sector at risk, warns Boulanger, who wonders whether efforts to regenerate vegetation will be able to keep up with the losses.

The communities most affected by the fire are remote and have relatively limited resources: 75% of the evacuees in July were indigenous peoples.

“This increasing severity of extreme events and the probability of extreme events occurring will not stop until we reach zero emissions and stop emitting additional greenhouse gases into the atmosphere,” Barnes said, adding that “it’s not too late” to press the political leaders to change course.

The World Weather Attribution is an international collaborative group that has conducted over 50 studies on extreme weather events to date, with results subsequently reviewed by peers in specialist publications.