Canadian wildfires fueled by climate change, study shows

When New York was choking on the smoke from distant eastern Canadian wildfires in early June, it was just the beginning of the huge blazes. 

By August, the fires had spread to Canada's west coast and have now burned nearly twice as much nationally than the previous record set in 1989, according to a new report by the World Weather Attribution (WWA), a climate change research initiative.  

The unprecedented 14 million hectares (34.6 million acres) of burned area — larger than Greece — prompted the WWA to see if and how climate change amplified the massive 2023 Canadian wildfires. It is the latest of more than 50 studies by the researchers seeking to quantify how much human-driven climate change influences extreme weather. 

Focused on the province of Quebec, the report concludes that climate change, caused primarily by burning fossil fuels, helped create dry, "fire-prone" weather about 20-50% more intense than average.   

Unusually low precipitation led to an arid and warm spring in Canada, including in Quebec, which caused snow to melt more rapidly than usual and brought forward the start of the fire season, according to Yan Boulanger, Research Scientist at Natural Resources Canada, and a report author. 

With the world having already warmed around 1.2 degrees Celsius (2.2 degrees Fahrenheit) since the late 1880s, global heating has doubled the chance of the extreme fire event witnessed this year in Canada, according to the study.  

"It's important that we can put a number on the impact of climate change," Boulanger told DW.  

The study also showed that climate change made the long duration of the 2023 wildfires from early June to late August seven times more likely.  

"The word 'unprecedented' doesn't do justice to the severity of the wildfires in Canada this year," Boulanger said. "From a scientific perspective, doubling the previous burned area record is shocking."  

Climate-influenced conditions create a tinderbox 

Factors including rain and snowfall, temperature, wind speed and relative humidity inform the Fire Weather Index (FWI) used by WWA researchers to measure the risk of wildfires. The researchers calculated the FWI value back to 1940, with 2023 having set a new record.    

The very high FWI this year means forests and vegetation are drier and more flammable, perfect tinderbox conditions for wildfires partly sparked by lightning strikes in early June, the report states.

"Climate change is greatly increasing the flammability of the fuel available for wildfires. This means that a single spark, regardless of its source, can rapidly turn into a blazing inferno," Boulanger explained.

"What is striking about this event is just how big it's been across all of Canada," said Clair Barnes, a research associate at the Grantham Institute for Climate Change and the Environment, Imperial College London, and lead author of the report.  

She told DW it was "shocking" that fires that started in the east of the country in June were still burning in the west and far north of Canada in late August.  

Barnes also noted that studying the impact of climate on wildfires is often complicated due to highly variable regional weather conditions. 

"But there was a very clear result in this case," she said. "This kind of fire weather is twice as likely as 100 years ago."

Canadian wildfire carbon emissions doubled 

The 2023 wildfires have produced record carbon emissions, worsening climate change. 

Canada's boreal forests hold around 11% of terrestrial or above-ground carbon, making it the biggest carbon sink of its kind. But by early August, wildfire carbon emissions were double the previous record, according to Europe's Copernicus Atmosphere Monitoring Service (CAMS). 

Researchers have indicated more frequent and intense Canadian wildfires across recent decades have transformed these forests from a store to a source of planet-heating greenhouse gas.   

Meanwhile, the 2023 emissions are set to increase further as fires in the west and north remain out of control.   

Cutting emissions key as wildfires set to worsen 

Experts say that the failure to cut emissions causing global heating in line with internationally agreed climate targets will increase the intensity and breadth of these fires.  

"Until we stop burning fossil fuels, the number of wildfires will continue to increase, burning larger areas for longer periods," said Friederike Otto, a senior lecturer in climate science at the Grantham Institute for Climate Change and the Environment and a co-author of the WWA report.   

"Increasing temperatures are creating tinderbox-like conditions in forests in Canada and around the world," she added.   

But the clarity of the WWA attribution study, which lead author Clair Barnes says is one of "only a handful" to investigate the influence of climate change on fire weather, could also help communities better adapt and build resilience to wildfires raging globally from Greece to Hawaii.    

By helping to understand better the risks of global heating in fire-prone regions, such research can help "reduce the severity of emergencies and disasters on people living in Canada and around the world," said Conrad Sauvé, President and CEO at Canadian Red Cross, who also contributed to the WWA report.  

"We will have to adapt to the fact that these fires are becoming more frequent," said Yan Boulanger.

Edited by: Jennifer Collins