The sleeping giant of the North

Margaret Munro
CanWest News Service
05-Oct-2006

MACKENZIE RIVER DELTA, N.W.T. ­ The sun is beating down on an icy bluff, sending chunks of ancient permafrost crashing to the ground.

Rivers of mud stream off the exposed permafrost, cracking and dripping in the 20 C late-summer heat. Enormous ice wedges that have grown metres long over the eons protrude from the top of the bluff like giant fangs.

“Is this cool or what,” says Scott Dallimore of the Geological Survey of Canada as he scrambles out of a helicopter in his hip waders. He heads for the steel grey bluff to take a closer look. But the melted permafrost is like quicksand and stops him in his tracks.

“We first found this exposure two years ago,” says Dallimore. The contorted pattern of the exposed permafrost suggests it may be hundreds of thousands of years old.

“It’s been frozen like this forever.”

But not for long. The bluff, on an island that is one of the anchor sites for the proposed $7-billion Mackenzie Valley pipeline, is melting away at the rate of 10 to 20 metres a year. So are hundreds of other permafrost ridges and cliffs across Canada’s North.

Geoscientist Rob Bowen, working with Dallimore to assess gases escaping from the frozen ground, likens permafrost to a “sleeping giant” that could awaken with potentially catastrophic consequences.

One nightmare scenario suggests that as permafrost warms it might belch out enough methane ­ a greenhouse gas ­ to trigger runaway global warming. There is some evidence such giant burps have occurred in the past.

Permafrost also contains large stores of mercury, a neurotoxin, and massive amounts of soil carbon, which could speed global warming.

But it’s the water melting out of the upper layer of permafrost that’s of immediate concern to engineers and northern planners. The so-called “active” layer ­ the top metres or two of permafrost that melts every summer and then refreezes ­ is becoming more active, playing havoc with the region’s infrastructure. And vulnerable permafrost cliffs and ridges are melting, sending enormous blocks of the frozen ground sliding and toppling into Arctic seas and rivers.

Permafrost covers close to 20 per cent of the planet and almost half of Canada ­ down to a depth of 700 metres in parts of the Western Arctic. There is so much permafrost underground and beneath the Arctic seas that scientists say it’s not going to disappear anytime soon.

“It’s not so much a question of permafrost melting, it a question of it changing,” says Dallimore.

Gases could be liberated even if the “deep” permafrost warms just a few degrees, he says. And there is evidence the frozen ground is warming.

Geographer Christopher Burn of Carleton University runs North America’s longest running permafrost monitoring experiments on the Mackenzie Delta. He inherited the Illisarvik and Garry Island monitoring sites from Ross Mackay, a retired University of B.C. professor widely described as the father of permafrost science.

“Climate change is happening, there is no question in my mind. I see it on the ground and I see it in the ground,” says Burn. As evidence he points to the willow trees, lupines and shrubs that have moved onto his expansive research site, which used to be barren tundra.

But it is the change underground that makes the site so significant. Fifteen metres below ground the temperature has risen 1.5 degrees to -6.5 C since 1970, says Burn, who has a growing collection of thermometers and gauges dangling down drill holes.

“When temperatures are rising 15 metres underground, it’s not variation, it’s a change,” he says.

Burn flies in from Ottawa five times a year to collect data at the “number farm” he shares with reindeer, swans and sandhill cranes. To measure the active layer, he jams a long metal rod known as a “gooser” into the permafrost until it hits frozen ground. Special gauges measure the insulating effect of snowdrifts. He and his students also monitor a pingo, a giant ice blister growing on top of permafrost, and ice wedges, metres long icicles that grow in and deform the upper layer of permafrost.

Burn’s work gives a detailed read on how permafrost on the edge of the Beaufort Sea has behaved since temperatures started to climb here in the 1970s, putting the region on the front line of climate change.

The challenge now is to expand the picture deeper underground and to other Arctic sites.

“The vastness of the region and the challenge of understanding it are out of this world,” says Dallimore. He heads a international group that wants to drill into the deep permafrost to fill significant gaps in knowledge about the gases and microbes found in the icy ground and how they will behave as temperatures climb.

“The concern is that permafrost at depth may change in ways we don’t understand,” says Dallimore, an authority on the methane and concentrated gas hydrates trapped in the frozen ground. “It could release pressure, release gas hydrates.”

Another team of federal and academic researchers wants to set up monitoring sites on Ellesmere Island, North Baffin Island, Eastern Hudson Bay, and the Beaufort coast to better gauge how climate change will impact the erosion and permafrost “block failures” already transforming some coastlines.

“The permafrost is a lot more vulnerable on the coast because it’s being attacked on all sides, by warmer water, winds and waves,” says Nicole Couture, an earth scientist and team member from McGill University.

She’s just back from three weeks on Herschel Island off the north Yukon coast where she and her colleagues were sizing up the massive blocks of permafrost peeling off the island’s 30-metre coastal bluffs. They’re among the most spectacular “block failures” in the world, with chunks of frozen ground up to five metre wide and 40 metres long, toppling off the bluffs and melting into the sea.

The proposed monitoring program would make such research easier by providing financial and technical support for work in remote corners of the north where costs are prohibitive ­ helicopters cost close to $2,000 an hour ­ on-the-ground support is now minimal, and weather can turn on a dime.

Couture and her German colleagues were wrapping up their fieldwork on Herschel when a storm rolled in. It flooded the airstrip where a Twin Otter was scheduled to pick them up. After a frustrating half-day on a balky satellite phone, Couture managed to get a floatplane in and loaded before the clouds closed in. Then, when the scientists finally arrived in Inuvik in the evening, power failures and freezer problems almost thawed hundreds of permafrost samples they had brought back.

The samples should help reveal how much carbon is falling into the sea with the frozen ground, which could be a significant player in the so-called “carbon budget” that drives global warming. It is estimated permafrost holds about one fifth of the carbon stored in the world’s soils.

“What is happening along the coast is, I think, crucial,” says Couture.

The permafrost failures and erosion appear to be accelerating as temperatures climb, wave action increases and sea levels rise. But it is hard to be certain, says Couture, as there is so little historical data available.

It is a common refrain. Dallimore and his team are studying “gas seeps” in permafrost in the Mackenzie Delta that are venting methane into the atmosphere. The researchers say so little is known about the phenomenon, it is impossible to say if the venting is increasing or not.

This summer they used “seep suckers” and sonar devices to sample and measure the escaping gas that makes patches of water in the Mackenzie delta bubble and roll like boiling water.

They also pulled on wet suits and dove down to the murky bottom to check out some of the 14 seeps found within 15 kilometres of their camp site.

“They’re like hot-tub jets,” Bowen says of one set of gas vents that have blown a small crater in the bottom and carved out a cove in the river channel. In winter, the gas keeps spewing out, preventing ice from forming over the seeps even when temperatures drop to -40 C.

The biggest seep found so far releases enough gas to fuel a flare almost five metres tall, or as much greenhouse gas as 7,238 cars, according to Bowen’s calculations.

Huge stores of methane are locked in the permafrost as swamp gas, natural gas and in highly concentrated frozen gas hydrates, says Dallimore. There’s been speculation for years that frozen hydrates might escape as the climate warms, “detonating” an even faster rise in global temperatures. Recent research indicates methane escaping from wetlands, permafrost and gas reservoirs ­ but not hydrates ­ may have played the lead role in warming the climate in the past.

Current understanding of the methane and its movement through permafrost is so minimal, Dallimore doesn’t know where the gas leaving the seeps originates, let alone how much temperature change in the ground it would take to increase the amount of escaping gas.

“There are just so many unknowns,” he says.