Mapping project nearly doubles tally of Canada's Arctic `volcanoes'
Pingos, volcano-shaped cones of ice and sand, are an iconic symbol of the western Arctic, and thanks to a grounded geologist and modern mapping techniques, Canada just got a lot more of them.
About 1,000 more, in fact. Enough to vault the Northwest Territories past neighbouring Alaska as the pingo capital of North America.
“Pingos are a very important part of the landscape, both as a natural feature, but also a cultural feature,” said Stephen Wolfe, a research scientist with the Geological Survey of Canada. “They've been used for navigation and landscape recognition, just like inukshuks. When you travel over the land, you'd see the pingo and know when you were coming home.”
There's even a national historic site — Pingo Canadian Landmark — dedicated to protecting a series of prominent pingos outside Tuktoyaktuk on the shores of the Beaufort Sea.
Pingos are found in areas of permafrost and sandy soil like the area around Tuktoyaktuk on the edge of the Mackenzie River delta. Though they look like mini-volcanoes, and some even have a bowl-shaped crater on top, they are the result of a completely different process. Pingos form when small tundra lakes drain, exposing the lake bottom to the freezing Arctic air. Groundwater in the soil freezes, pushing the earth upwards. The tallest, such as Ibyuk Pingo, the showpiece of Pingo Canadian Landmark, rise as much as 50 metres above the tabletop-flat tundra and measure 300 metres across at the base.
“They're basically just giant ice cubes inside,” Wolfe said.
Many of Canada's pingos were identified and mapped in the 1970s by renowned Arctic researcher J. Ross Mackay of the University of British Columbia. Early researchers used black-and-white air photos to identify the features and plot them on maps by hand.
“The data they had were quite poor. You can be sure that if they identified a pingo, they were correct. But now when we put them on a digital map they can easily be off by a kilometre or more,” Wolfe said. “They might have placed it in the middle of the water or on top of another pingo. With satellite imagery, we can pinpoint it within 50 centimetres on the ground and within 20 centimetres vertically.”
Last year, when Wolfe was unable to travel for his normal field research in the western Arctic because of an injury, and again this year when he was grounded because of the COVID-19 pandemic, he decided to use his downtime to try to map pingos more accurately. He used high-resolution digital imagery of the Arctic — and Google Earth — to scour the Lake Erie-sized area around Tuktoyaktuk where pingos are found.
When he was finished, he'd identified 1,000 new pingos, nearly doubling Canada's pingo count to 2,160. He even identified five new pingos, and possibly a sixth, within the boundaries of Pingo Canadian Landmark, which formally only recognizes eight pingos.
But Wolfe's pingo map isn't just for bragging rights. Pingos are key indicators of climate change and the state of the permafrost that underlies them. About five per cent of the pingos identified in the 1970s have been lost to coastal erosion, and Wolfe has identified about another five per cent that have collapsed because their ice cores melted away.
“This is where you can use the pingos to determine the health of the permafrost,” he said.
“If you see collapsing going on, you can ask, `Is this climate change we're seeing in the western Arctic?'
“Are we in danger of losing all pingos? I'm not going to say we're not. Pingos are a vulnerable feature. It's good that we know how many there are and how many have collapsed.
“How close are we to losing all our pingos? It's hard to speculate, but I wouldn't want to see us warm by four degrees.”
Pingos aren't unique to Canada. They also occur in Russia and along Alaskan coast.
“Alaska has a lot of pingos and a high density,” Wolfe said. “But now that we've added 1,000 more, we might take the prize back again.”