The climate-driven wildfires currently razing Canada’s northern forests and darkening skies across the continent may have an unexpected effect: according to a new study, the fires may reduce global warming and sea ice melt in the Arctic.
The rising impact of blazes in Canada and Siberia’s boreal regions over the next 35 years will slow warming by 12 per cent globally and 38 per cent in the Arctic, according to recent climate modelling research at the University of Washington (UW). But the study’s authors warn that while the study may sound positive, it’s just one part of a trend that overall spells major trouble for northern ecosystems.
Boreal forest fires affect the climate as smoke particles scatter sunlight back into the atmosphere. These particles, or aerosols, also attract water droplets in clouds making them more reflective — reducing warming trends during the summer in northern areas, said lead author Edward Blanchard-Wrigglesworth, a UW research associate professor of atmospheric and climate science.
This effect outweighs other factors like the heat the fires themselves release, or the warming that occurs when black soot falls on white ice or snow, absorbing rather than reflecting sunlight, he said. It also outweighs the planet-heating effect of the carbon dioxide released by the fires.
Previous climate models haven’t accounted for the increasing scale of wildfire events in boreal forests over the last decade in Canada and Siberia, said co-author Dargan Frierson, a UW associate professor of atmospheric and climate science.
The team used the Community Earth System Model (CESM) in the study but hope other climate models and scientists will incorporate the new approach to improve accuracy and understanding of boreal fires impacts, Frierson said.
Though boreal fires occur in summer, the study found warming was slowed year-round from in the Arctic to as far south as Northern California. This relative cooling results in thicker Arctic ice that lasts into the following winter and making the season colder.
The reducing warming in northern regions also has the effect of pushing tropical rains further south.
Additionally, conventional modelling predicts nearly a complete loss of summer sea ice by 2060. However, the study suggests that approximately 2 million square kilometres of summer ice, an area slightly larger than Mexico, will still be present by that time.
However, while the findings show wildfires mitigate global warming it doesn’t significantly change the overall trajectory of the climate crisis, the authors said.
“It’s an oversimplification to call the study a good news story because large boreal fires still have severely negative impacts on human health and on forest biodiversity,” Blanchard-Wrigglesworth said.
“The most significant takeaway of the study is that how boreal forest fires evolve in the next few decades matters for climate, especially in northern regions, and that we need to better understand the process.”
If the intensity of boreal fires drops naturally, or due widespread fire suppression, the climate cooling effect would likely fade within a few years, Blanchard-Wrigglesworth said.
“We need to do more research to address this question,” he said.
Warming in other regions like the tropics or southern hemisphere where some of the most severe climate change impacts are expected won’t be significantly buffered by boreal fires, he added.
“The primary cause of climate change is the burning of fossil fuels, which remains the primary driver in our new simulations and still drives significant warming,” Blanchard-Wrigglesworth said.
Frierson agreed, saying the study results don’t reduce the need to slash carbon pollution as fast as possible.
The cooling effects of boreal wildfires only slow the runaway truck of climate change, Frierson said, noting wildfires carry huge costs for people and wildlife that aren’t captured in the study.
The scale of boreal wildfires like those Canada experienced in 2023, when more than 15 million hectares were razed and 200 communities had to be evacuated, bordered on “apocalyptic,” Frierson said.
Smoke from Canadian wildfires this season is already reaching Europe, prompting air quality alerts in the US, and displaced thousands of people in Alberta, Saskatchewan and Manitoba.
“These [boreal fire] impacts that lead to less warming actually happen due to pretty catastrophic situations,” Frierson said.
“We need to take even more rapid action on climate, because that’s the only way to get rid of both the fires and much more significant warming.”
