Forests can be a sink _or_ a source for atmospheric CO2 depending on the ratio of new growth to decay or fire.

So what happens when Canada's boreal forest (the second largest in the world, after the Russo-Scandinavian one) is subject to longer and more intense forest fire seasons in a warming climate? What happens to millennia of stored carbon in the form of hundreds of thousands of square kilometers of peat bogs and permafrost as they respectively warm an dry out or thaw?