A double effect of boreal forest fires on climate

Summer and its peak temperatures have, in recent years, increasingly been the scene of devastating fires. The dramatic increase in these fires, particularly in the forests of the Far North, is a symptom of global warming. 

Paradoxically, these fires contribute to significantly reducing global warming. This is revealed in a study conducted by UCLouvain and the University of Washington, published in the prestigious scientific journal PNAS.

Clouds lightened

Specifically, this study shows that if we take into account a future intensification of fires in boreal forests, such as those in Canada and Siberia, based on current trends, global warming could be reduced by 12% globally and 38% in the Arctic by 2060.

As result of a collaboration between Patricia DeRepentigny, a researcher at the Earth and Life Institute at UCLouvain, and scientists at the University of Washington, this research reveals an unexpected role played by forest fires in the Far North: slowing down global warming.

How is this possible? The smoke from these fires contains aerosols that lighten clouds and reflect sunlight, cooling the atmosphere in summer and slowing the melting of Arctic sea ice. 

This occurs despite the warming effects of the fires themselves, due to factors such as soot falling on the ice. 

The increase in boreal forest fires, which has been ignored in current climate models, could therefore alter future projections.

Not a good news

But scientists at UCLouvain and UWashington are cautious about this seemingly good news: this cooling does not offset the many harmful effects of fires, such as risks to health, biodiversity, and carbon released by burned forests. 

And if fires continue to increase, the trend could reverse. So this is not so much “good news” as an essential piece of the climate puzzle. 

The scientific article can be found in PNAS website.

This article was originally written in French by the AREC team of UCLouvain. It is available to be read here.