A new study is telling us more about the relationship between wildland fire and thawing permafrost in the Northwest Territories, as part of a partnership between the Government of the Northwest Territories (GNWT) and researchers at the University of Alberta.

University of Alberta researchers Carolyn Gibson and David Olefeldt recently published a new study examining the impacts of wildland fire on permafrost in the NWT and northern Alberta, finding that wildland fire is responsible for approximately 25% of permafrost thaw in the last 30 years. The study also found that wildland fire has tripled the rate of abrupt permafrost thaw.

Wildland fire results in an unfrozen soil layer that persists throughout the entire year. These altered conditions last for about 30 years after the fire and begin to recover to pre-fire conditions as post-fire vegetation recovery occurs.

“Wildfire is a very important force on the landscape, and what we see here is that it continues to have impacts long after the burning is done,” Gibson says.

Permafrost is becoming increasingly vulnerable to thawing due to climate change. With fire frequency also increasing under a warming climate, this study emphasizes the need to consider wildland fires when projecting future circumpolar permafrost thaw.

“Historically, permafrost in this region underwent a natural cycle of thawing and reforming; however, given current climate conditions and projections for the future, this fire-induced permafrost thaw appears to be irreversible,” according to Gibson.

The 2014 NWT fire season presented a unique opportunity to address important knowledge gaps across a diverse range of ecological conditions and levels of burn severity in the southern NWT. A joint GNWT-Wilfrid Laurier University workshop was held in 2015 to bring together local and outside practitioners and researchers to prioritize knowledge gaps and envision a research agenda to address those gaps with new research. This article by Gibson and Olefeldt is part of that expansive research program.

Read the study, “Wildfire as a major driver of recent permafrost thaw in boreal peatlands”, published in Nature Communications.