They may not be a skin problem, but frost blisters are flaring up along the Inuvik-Tuktoyaktuk Highway as global warming progresses.
Often appearing further out from the highway, one was recently discovered by the Imaryuk Community Monitoring program and provided scientists at the Aurora Research Institute and the NWT Geological Survey to study the up-shoots of soil, as this phenomenon only happens on the permafrost.
“You can kind of think of permafrost as the frozen foundation for Northern ecosystems. We use it as a foundation for infrastructure as well,” said NWT permafrost science manager Steve Kokelj. “Permafrost keeps water close to the ground surface — it’s one of the reasons there’s so much water around here. IIn an area outside the north, that water would just disappear into groundwater.”
Kokelj said climate change was bringing wetter and warmer autumns to the Beaufort Delta, which was leading to more water flowing along the permafrost as temperatures drop. Along physical barriers to water, such as the ITH or ground that has already frozen for the winter, water from rainfall pools. It slowly seeps downward until it reaches the permafrost. If enough water accumulates on the permafrost, when temperatures drop it freezes and the only direction the pressure can expand is upwards — up to two metres.
Along the ITH, culverts are in place to allow water passage under the road, however the volume of water is sometimes higher than the infrastructure can keep up with.
Sort of like a pingo, Kokelj explained, the ice build up pushes surrounding soil further up, which in itself can damage infrastructure, particularly gravel roads like the ITH. Not like a pingo, however, is how the open frost blister can actually bring liquid water to the surface and the fact they happen year-to-year — and fast.
“In some cases it’s a little blister, and in some cases it can be a big area that just gets heaved up,” said Kokelj. “From an ecological perspective, it can tear up plant roots and so forth — you can see areas of dead vegetation that were affected by the frost blister. When that ice that’s in the frost blister melts the following summer, that tundra starts to fall back and essentially gets churned up, which disturbs the permafrost and can precipitate additional thawing in the future.”
Protected from freezing temperatures by layers of snow, which is in fact a fantastic insulator of heat, water can remain liquid even while surrounded by permafrost and seasonally frozen soil.
If enough ice builds up, it can push the liquid water to the surface, where it quickly encounters temperatures below -20 or colder and freezes, creating a phenomenon called icing, which can be hazardous to motorists, freeze culverts and lead to further blockages of water flow come spring melt.
“Some people find it hard to believe water is actually coming up to the surface of the ground when it’s -30C out,” he said. “But if it veneers the road surface, it’s dangerous. As it takes longer for the active layer to freeze in the winter as the climate warms, the ability for water to keep moving around in the winter time increases as well.
“It takes awhile for the top metre to re-freeze, and if there’s water running across the permafrost it can keep filling lakes. Imagine lakes like a cup, if they get fed with more water they spill over. That water makes it way down a creek system, and creek systems accumulate lots of snow. It takes a lot of energy to turn water into ice, so the water is just warm enough to keep trickling.”
Time is usually of the essence with frost blisters, which can be removed with equipment but get progressively worse the longer they’re left.
Noting research on frost blisters was highly dependant on their work, Kokelj praised Imaryuk for their ongoing presence on the highway that allows for constant monitoring of the area.
“A lot of times frost blisters go unnoticed,” he said. “But here it occurred right next to the road and the Imaryuk Monitors who are driving the road every day were able to pick up on the tundra heaving and also the icing that flowed in the area, so they really got us on to what was going on out there. After the frost blister grew, water started to cover the tundra and form an icing. There was a lot of surface ice. The frost blister itself was completely buried in ice.
“The Imaryuk Monitors watch the road and the surrounding environment, so an early warning on these is helpful. They’re out there every day making these observations. It’s super-valuable.”