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Wildfires in Quebec that forced thousands of people from their homes earlier this summer were made at least two times more likely due to extreme weather conditions fuelled by climate change, new research presented Tuesday finds.

Published by World Weather Attribution, an international collaboration of scientists who study how climate change and extreme weather events interact, the study looked at how climate change made the fire-prone weather that fuelled both the peak intensity of the wildfires and the wildfire season as a whole more likely and extreme.

The Quebec wildfires between May and July made international headlines. Throughout that period, 5.2 million hectares burned and between June 1 and June 25, more land was burned than in the past two decades, said Yan Boulanger, co-author and research scientist at Natural Resources Canada. The fires followed an especially dry spring, and smoke from the fires spread across Canada and to the United States. Its impacts were felt disproportionately by remote communities, especially Indigenous communities, the report noted.

The weather conditions that caused the peak of the wildfires were made 20 per cent more likely by climate change. Climate change also made conditions affecting the season as a whole at least seven times more likely, and 50 per cent more intense, explained Clair Barnes, research associate at the Grantham Institute for Climate Change and the Environment, at a press briefing.

To examine how warm temperatures lead to drier conditions and create conditions for fire to spread, the scientists used the Fire Weather Index (FWI), a tool used by the Canadian government and other countries, which estimates the risk of wildfires based on weather, temperature, humidity, wind speed and precipitation.

The index gave the scientists an understanding of the conditions during the peak of the fires and the overall period studied. To understand the correlation between the FWI measurement and climate change, they cross-referenced climate models, which simulate the Earth's weather patterns over time, to see that the differences in weather, and therefore conditions that lead to wildfires, have increased as global warming has climbed.

While the role climate change has played in wildfires is clear, Barnes explains that few studies have been done that actually measure the effects of climate change on weather that makes fires worse and more prevalent. Wildfires are more complicated to study than other extreme weather events because the conditions that cause them are unique to different areas of the world, she said.

Boulanger said the word “‘unprecedented’ doesn’t do justice to the severity of the wildfires in Canada this year,” which have been the most devastating ever recorded. So far, 14 million hectares have burned and about 200,000 people have been evacuated across all corners of the country.

“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 said.

The weather conditions that caused the peak of the wildfires were made 20 per cent more likely by climate change. Climate change also made conditions affecting the season as a whole at least seven times more likely, and 50 per cent more intense.

The same group found that hundreds of deaths and devastating wildfires in North America in June 2021 were made 150 per cent more likely due to climate change, caused largely by the burning of fossil fuels.

While the way humans interact with the land is also contributing to the severity of wildfires — modern logging practices that fracture the landscape with roads and leave large piles of brush are creating conditions that lead to fire spreading, for example — climate change is playing a huge role. While the fire season specifically in Quebec broke records, that doesn’t mean it’s unusual, said the authors.

Based on today’s climate, Quebec’s wildfires early this summer were a once-in-25-year event, or there is a four per cent chance of a similar event occurring each year. However, as the planet warms, that likelihood rises.

“Increasing temperatures are creating tinderbox-like conditions in forests in Canada and around the world,” said Friederike Otto, co-author and senior lecturer in climate science at the Grantham Institute for Climate Change.

“Until we stop burning fossil fuels, the number of wildfires will continue to increase, burning larger areas for longer periods of time.”

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