Yukon ice offers cold comfort to climate fears

The oldest-known ice on the continent has been discovered near Dawson City, producing evidence that climate change may not melt the icy corners of…

The oldest-known ice on the continent has been discovered near Dawson City, producing evidence that climate change may not melt the icy corners of the world as quickly as some feared.

The chunk of ancient ice, dated to be about 750,000 years old, is testament, in the words of one scientist, to the “stubborn” character of permafrost — the frozen dirt that covers one quarter of the land in the northern hemisphere.

The speed that permafrost melts is of great concern because the frozen mud contains vast stores of carbon. If the world’s permafrost melted in coming decades, as some climate change models hold, that carbon may be released into the atmosphere as greenhouse gases, and exacerbate global warming.

But the ancient Yukon ice chunk suggests otherwise.

It appears to have survived two sweltering periods of the Earth’s history, through temperatures warmer than today.

“This isn’t saying we don’t need to worry about global warming,” said Duane Froese, an assistant professor from the University of Alberta and the lead researcher behind the discovery.

“This is just saying that the deep part of that equation, the deep permafrost, which has huge, huge stores of carbon, is probably stable, if we use the past response to climate as an idea as to what will happen in the future.”

It was previously believed all the patches of permafrost had melted in interior Alaska and Yukon during a warm patch about 120,000 years ago, said Froese.

The ice wedge indicates that is not the case.

On top of this, the ice would have also weathered another warm period, about 400,000 years ago.

The ice was found near Dominion Creek, about 30 kilometres southeast of Dawson City, during the summer of 2000. It forms a wedge within a crack in the permafrost, and is several metres beneath the surface.

The discovery would never had been made at all, said Froese, if not for placer mining activity in the area, which had eroded the side of a valley to expose the ice.

Ice is hard to date, so the significance of the discovery was not, at first, obvious. The clue that led to the ice’s age was a coating of volcanic ash atop the permafrost and ice. The ash must have fallen after the ice had formed, and it could be dated.

The discovery was finally made public prior to the publication of an article by Froese and his colleagues in the journal Science on Friday.

Some critics have suggested we should not read too much into Dawson’s ancient ice chunk. They say there is little reason to believe the rest of the world’s permafrost will behave in the same way. It may be an anomaly.

Exactly so, said Froese. The lesson to take away from his discovery is that permafrost is influenced by a whole range of factors other than temperature, he said. Cover offered by vegetation and soil, for example, may be “almost as important” as temperature.

Well-protected permafrost may survive further warming, but that “doesn’t mean we’re out of the woods for shallow permafrost,” said Froese.

Melting permafrost has already caused roads to buckle and buildings to sink into the tundra in parts of the world such as northern Quebec. But don’t expect permafrost to melt en masse, or in as dramatic a fashion as the enormous Arctic ice shelves shearing into the ocean, said Froese.

“Permafrost is different from that. Permafrost has resilience.”

Just Posted

Chief Medical Officer of Health Dr. Brendan Hanley announced 29 new COVID-19 cases on June 19 and community transmission among unvaccinated individuals. (Yukon News file)
Yukon logs record-high 29 new COVID-19 cases

F.H. Collins prom attendees and some Porter Creek Grade 9 students are instructed to self-isolate as community transmission sweeps through unvaccinated populations

Crystal Schick/ Yukon News A former residential school in the Kaska Dena community of Lower Post will be demolished on June 21. Crystal Schick/ Yukon News
Lower Post residential school demolition postponed

On June 21, the old residential school in Lower Post will be demolished and new ground on a multi-cultural centre will be broken

Willow Brewster, a paramedic helping in the COVID-19 drive-thru testing centre, holds a swab used for the COVID-19 test moments before using it on Nov. 24. The Yukon government is reopening the drive-thru option on June 18. (Crystal Schick/Yukon News)
Drive-up COVID-19 testing opening June 18 in Whitehorse

The drive-up testing will be open from 6:30 p.m. to 9:30 p.m. everyday and increase testing capacity by 33 spots

A draft plan has been released by the Dawson Regional Use Planning commission on June 15. Julien Gignac/Yukon News
Draft plan released by the Dawson Regional Land Use Planning Commission

Dawson Regional Land Use Commission releases draft plan, Government of Yukon withdraws additional lands from mineral staking in the planning region

Yukonomist Keith Halliday
Yukonomist: Let them live in trailers

“I found Rome a city of bricks and left it a city… Continue reading

Whitehorse City Hall (Yukon News file)
City news, briefly

A look at decisions made by Whitehorse city council at its June 14 meeting

Murray Arsenault sits in the drivers seat of his 1975 Bricklin SV1 in Whitehorse on June 16. (Stephanie Waddell/Yukon News)
Bringing the 1975 Bricklin north

Murray Arsenault remembers his dad’s Bricklin, while now driving his own

A presumptive COVID case was found at Seabridge Gold’s 3 Aces project. (file photo)
Presumptive COVID-19 case reported at mine in southeast Yukon

A rapid antigen rest found a presumptive COVID case on an incoming individual arriving at the 3Aces project

Jonathan Antoine/Cabin Radio
Flooding in Fort Simpson on May 8.
Fort Simpson asked for military help. Two people showed up.

FORT SIMPSON—Residents of a flooded Northwest Territories village expected a helping hand… Continue reading

A woman was rescued from the Pioneer Ridge Trail in Alaska on June 16. (Photo courtesy/AllTrails)
Alaska hiker chased off trail by bears flags down help

ANCHORAGE (AP)—An Alaska hiker who reported needing help following bear encounters on… Continue reading

Two participants cross the finish line at the City of Whitehorse Kids Triathlon on June 12 with Mayor Dan Curtis on hand to present medals. (Stephanie Waddell/Yukon News)
2021 Kids’ Triathlon draws 76 young athletes

Youth ages five to 14 swim, run and bike their way to finish line

NDP MP Mumilaaq Qaqqaq rises in the House of Commons, in Ottawa on May 13, 2021. THE CANADIAN PRESS/Adrian Wyld
‘Unacceptable’ that Inuk MP felt unsafe in House of Commons, Miller says

OTTAWA—It’s a “sad reflection” on Canada that an Inuk MP feels she’s… Continue reading

Lily Witten performs her Canadian Nationals beam routine on June 14. John Tonin/Yukon News
Three Yukon gymnasts break 20-year Nationals absence

Bianca Berko-Malvasio, Maude Molgat and Lily Witten competed at the Canadian Nationals – the first time in 20 years the Yukon’s been represented at the meet

Most Read