Climate Change Affects the Resilience of Boreal Forests

Earlier this week, the Canadian Interagency Forest Fire Centre confirmed that there were 888 active wildfires nationwide and the number of out-of-control wildfires was 586. So far this year, the number of wildfires reached 4,152, devouring about 100,000 square km of land.

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Paul Beckwith, a climate system scientist, warned that the boreal forests in Canada's wildfire region will likely not regrow if the climate there has changed.

"We can't assume that when a forest burns down it will be replaced over time by another forest," he said, explaining that if the annual temperatures have changed and the precipitation in that region has also changed and reduced, the region where the forests used to be will become savanna, mostly grasslands with the odd, isolated trees, or just pure grasslands.

Formerly an assistant professor at the University of Ottawa, Beckwith studies abrupt climate system changes related to oceans, biosphere, air temperatures, the lithosphere and cryosphere.

"We haven't seen fires like this before in Canada for an awful long time. Maybe ever," Beckwith said, adding that wildfires in Canada are exceptional by any measure and this wouldn't be happening without the heat waves and the lack of moisture.

A boreal forest is a wet and cold adapted forest which gets lots of rain and sunlight. But now Canada has warmed at over double the rate than the rest of the planet. Typically the return time of large fires in a boreal forest is about 50 to 100 years and forest fires are a part of the lifecycle of the boreal forests.

If a fire ignites in July or August, it's generally out in the fall, because as the weather gets colder, there's more rainfall. So the fire is there left alone to burn if it's not interfering with infrastructure, towns, roads, and rail, etc. It just burns itself out. But when there are too many at any one time, it really overstretches firefighting resources.

"The problem is that when you get these fires igniting in the remote areas in the spring, do you really want to let them burn all summer? We've got to do firefighting differently in this country, for sure," Beckwith said.

The problem with the forest burning is that the forests are a huge sink of carbon. And when they burn that carbon is released rapidly to the atmosphere-ocean system. And you also lose the carbon sink and the forests no longer exist to absorb all of that carbon.