The Weird Cooling Effect of Wildfires

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HArdly two months after the historic season of Canada Forest Fire, the country is already on the right track to one of the most devastating fire seasons ever recorded. The racing flames claimed the lives of two lives and moved more than 20,000 people in Manitoba alone, most of the evacuations belonging to the First Nations of the province. More than 7.8 million acres have burned, exceeding the average zone burned in one year, and forecastists predict that the season will extend for at least three additional months, perhaps more. It is a clear demonstration of the way in which climate change has increased the potential of heels of enormous flames to tear forests and meadows.

However, most of the dominant climate models have failed to incorporate the increase in fire activity rates recorded in the boreal forests of the earth. Instead, these models tend to assume that fire activity and related emissions would remain stable with levels connected at the end of the 2010s. In an article published in the Proceedings of the National Academy of Sciences In early June, a trio of researchers studied what would happen to climatic projections if they directed new models that more precisely represented the gravity of the fire season in boreal forests in recent years and in the future.

What they found seems counter-intuitive: according to new models, smoke from all forest fires could actually alleviate global warming of around 12%. Dargan Frierson, atmospheric scientist and co-author of the recent article, says that he “expected the opposite to happen”.

Warming is more than offset by the net cooling effect that smoke and other aerosols create.

To calculate the impact of the increase in the activity of shots on climate change, Frieurson and his colleagues have taken advantage of the global Fire emissions database, which catalogs the levels of smoke, soot and co₂ Issued by fires during a given year. They then analyzed the relationship between fire activity, fire -related emissions and global temperatures between 1997 and 2023 and connected these variables to existing climate change models.

“Forest fires have an effect on the climate in many ways,” explains Frieurson. These fires release smoke, carbon dioxide, methane and all kinds of other pollutants, including sometimes toxic substances. A large part of this mixture of emissions has a warming effect on the planet, whether by adding more greenhouse gases to the atmosphere or darken the surface of snow and ice, which made it capture more heat and melt more quickly.

But the models that Frieurson and his colleagues have run found that this warming is more than compensated by the net cooling effect that smoke and other aerosols create when they brighten up the clouds and prevent part of the heat from the sun to reach the surface. This even manages to prevent part of the sea ice in the Arctic from melting; Consequently, the ice lasts longer and remains thicker in the summer and fall than it would do otherwise, which leads to even more cooling in winter compared to what most other climatic models suggest.

However, while Frieurson and his team are able to say with a certain confidence that the increase in fire activity could reduce global warming in the world and 38% in the Arctic, Hamish Gordon, atmospheric scientist at Carnegie-Mellon University, says that “precise figures are extremely uncertain”. Gordon does not emphasize this to suggest that there is something wrong with the paper itself. “I like the study,” he says, but the authors must do a lot of hypotheses and there are a lot of uncertainty inherent in climate modeling, especially when you are dealing with aerosols such as forest smoke, which remain one of the most difficult things for climatologists to represent precisely in their models. Aerosols, the tiny particles suspended in the atmosphere, behave in a complex way: a dispersed light, others absorb heat, some both; Throughout their clarification of the clouds by multiplying the water droplets, sometimes even causing spontaneous snowfall.

Frieurson himself says: “The figures should not be taken too seriously at this stage.” The document did not aim to determine the precise and final effect of the increase in forest fires on the world climate. Instead, the researchers wanted to highlight the importance of accurately taking into account these emissions in future climate models, especially since the intergovernmental panel on climate change prepares the reports in its seventh evaluation cycle.

But even if future analyzes reinforce the results of Frieurson and its collaborators and that they conclude that an abundance of smoke can have a pronounced cooling effect on the planet and the Arctic, this does not mean that these fires are somehow mild or benevolent. As a fire ecologist at the University of Nevada Reno, Erin Hanan underlines: “Changes in the fire regime in boreal regions are an ecological and human and human disaster.”

Lead image: Thmphotographs / Shutterstock

• Syris Valentine

  Published on June 25, 2025

  Syris Valentine is an independent essayist and journalist by emphasizing climate and social justice. Apart from his newsletter “Just Progress”, his work appeared in The Atlantic, Scientific American, Grist, And elsewhere.