Permafrost thaws as wildfires rage
Soil warming hurts infrastructure in N.W.T. town, Inuvik mayor says
Wildfires are rapidly thawing permafrost and as a result eroding infrastructure in Canada’s northern communities, according to a new study.
Research led by former University of Alberta student Carolyn Gibson found wildfires have caused about 20 per cent of all permafrost thaw — or 2,000 square kilometres — in Western Canada’s boreal peatlands over the last 30 years.
While the thick layer of frozen soil traditionally undergoes a natural cycle of thawing and reforming, an increase in fires and warming temperatures means the recent thaw appears to be irreversible.
“We think (the frozen earth softened by) abrupt thaw is not going to come back,” said Gibson, who conducted the research as part of her master’s degree studies at the U of A. The study was published in the journal Nature Communications.
She explained that permafrost is crucial for carbon retention, which means more carbon is now being released into the water and atmosphere, thus exacerbating the climate change that is already contributing to the spike in wildfires.
“It’s what we call a positive feedback system. These things are all connected to one another; as one gets worse, the other gets worse,” Gibson said.
The thaw has consequences for both the environment and any infrastructure that sits on previously frozen ground.
Permafrost areas are rich in lichen, a major source of food for caribou in the north. When the ground thaws, the animals leave, which in turn hurts northern communities that rely on the ecosystem for subsistence hunting and cultural identity.
Thawing land turns to muskeg, making travel exceptionally difficult, at times leaving pools of shin-high water where there was previously solid ground.
“If you’re going to build infrastructure on these areas, and they’re going to thaw, that infrastructure will inevitably be damaged in some way,” Gibson said.
“Once-sturdy travel routes are now becoming more variable. So an area that once maybe used to take you 20 minutes to get to, can now take upwards of an hour because you’re having to go around these areas that have now become wet because the permafrost is thawing.”
The mayor of Inuvik, a remote northern town of about 3,000 in the Northwest Territories, said he has noticed the effect of thawing permafrost on his town’s infrastructure. Maintenance costs are on the rise.
“We are on a regular basis now having to go in and level and regrade all of the water and sewer lines,” Jim McDonald said.
He added the Inuvik airport has had major problems with sinking on its runway in recent years, which could potentially be attributed to thawing. The phenomenon also seems to be taking a toll on local roads, which are especially expensive to maintain because Inuvik has to bring in people from outside the town for asphalt services.
“It does contribute quite a bit to the road conditions,” McDonald said. “With the movement and the melting ... there’s a lot more of the cracking and dips and that type of thing in the road.”
Gibson’s team used high-resolution satellite imagery to determine the scale of the thawing, comparing areas burned by wildfires to areas that did not. The thawed areas turned from a white blob on the images to lime-green moss, which she said is easy to pick up.