The influence of forest fires on climate: Advancing measurements of fire severity and long-term climate impacts of boreal fires
The climate balance of forest fires: northern fires are not simple climate amplifiers
Northern forests, such as the vast boreal forests of Canada and Alaska, are increasingly experiencing large wildfires due to climate change. These fires affect not only ecosystems and the amount of greenhouse gases in the atmosphere, but also the climate itself. At the same time, it is not yet sufficiently clear whether forest fires mainly contribute to warming or to temporary cooling in the long term.
I investigated how the severity of forest fires can be better measured with satellite images and how these fires affect the climate over decades. I show that the climate impact varies greatly from region to region: fires in Alaska cause warming on average, while fires in many parts of Canada actually have a cooling effect due to longer-lasting snow cover after the fire. However, climate change is reducing this cooling effect, so that future forest fires increasingly contribute to additional warming.
Great variations from area to area
My research shows that the influence of northern forest fires on the climate is much more complex than 'fires cause warming'. I show that the consequences can last for decades and vary greatly from area to area. Fires in Alaska cause additional warming on average, mainly because they emit a relatively large amount of carbon from vegetation and frozen soils. In many parts of Canada, fires are currently having a cooling effect, because the dark burnt ground remains covered longer in winter with a clear snow cover that reflects more sunlight.
However, this cooling effect is decreasing due to climate change: warmer winters mean less and shorter snow cover. As a result, the balance is shifting and northern forest fires will increasingly contribute to further warming of the climate in the future.
Targeted measures
The results of my research help better understand the role of ever-increasing forest fires in a changing climate. This knowledge is important for nature managers, policymakers and climate researchers who have to make decisions about fire prevention, forest management and climate adaptation in northern areas. By knowing the conditions under which fires are likely to have a strong warming effect, for example in areas with high carbon-rich soils and permafrost, measures can be used in a more targeted way.
More information on the thesis.