Arctic sea ice loss puts permafrost at risk of melting: report

News that the cover of Arctic sea ice was at its lowest point in recorded history last summer shocked climate-watchers around the world, but researchers now suspect the effects could ripple across the land as well.

A scientific paper to be published Friday argues that rapid sea ice loss speeds up melting of permafrost, the frozen ground that underlies vast swaths of the Arctic.

That means the ground on which everything from northern highways to megaprojects, such as natural gas pipelines, are built could become unstable.

"When you get these rapid loss events, you can see the temperatures on land increase," Andrew Slater of the University of Colorado said Tuesday. "The rate of warming increases."

Last summer, the Arctic Ocean lost about a million square kilometres of ice cover, an event that left the Northwest Passage open for the first time in history and drew headlines around the world.

Slater's study in the journal Geophysical Research Letters suggests that last summer's dramatic ice loss could be part of a 10-year shrinking cycle. That possibility is supported by other findings that sea ice is headed for another record low this fall.

If Arctic ice is in such a cycle, Arctic lands are sure to follow, says Slater's research. During periods of rapid sea ice thaw, computer models predict the rate of warming will increase 350 per cent.

That means that land along northern coastlines could be warming at the rate of five degrees each decade, with the highest temperatures occurring in the fall.

Nor is the effect limited to the shore. The paper suggests warming will speed up as far as 1,500 kilometres inland.

"Extensive and rapid sea ice loss results in strong and spatially extensive warming of the Arctic land," the paper says.

That rate of warming is likely to have serious consequences for permafrost.

"If you put more energy into permafrost, you're going to start to see some thawing," said Slater.

The most noticeable effects are likely to be seen along the fringes of the permafrost belt, where a degree or two either way can mean the difference between melting and stability.

Underground puddles called taliks can form, trapped between the stable permafrost below and the ground above. The taliks store heat through the winter and are likely to grow over the years, said Slater.

Unstable permafrost already threatens northern infrastructure and is becoming an increasing factor in northern life. In Yellowknife, an insulating liner had to be installed four metres under a 100-metre section of runway with a history of sagging. Highways all over the Western Arctic have struggled with collapsing roadbeds and the season for ice bridges and ice roads crucial to industry for moving supplies has shrunk by a month since the mid-1990s.

The federal government says at least six communities, mostly in the Mackenzie Delta, are highly vulnerable to infrastructure damage from climate change.

All this as energy companies in both Alaska and the Northwest Territories are considering massive pipeline megaprojects to carry millions of cubic feet of natural gas daily over land that could be among the most unstable.

"They should start thinking about those projects in the context of climate change," Slater said. "The study shows that you can get rapid bursts of change.

"You should get thinking about that in your design."

Melting permafrost could also release its stores of carbon dioxide, the main greenhouse gas, although Slater says warming temperatures could also cause more plants to grow in the Arctic, which would absorb carbon dioxide.

"There are a lot of things that can happen in terms of feedback. There are a lot of unknowns."