newsminer.com

BARROW –– Eugene Brower got out of his pickup truck, walked past a boat made of wood and seal skins, and opened the door to a small wooden shack. He lifted a rectangular cover in the floor and started to climb down into the ice cellar his father dug more than 50 years before.

“Ooh! It smells,” he said.

It was late September, a week before the start of the fall whaling season, and unseasonably warm. Brower swung his arm around and knocked off giant ice crystals that had formed on the dirt walls.

“Never used to have that,” he said. “And it looks smaller.”

Ice cellars are dug into the frozen ground, and the temperature in them typically stays well below freezing year-round. But strange things are happening now with ice cellars — people tell stories of taking the lids off them and seeing them filled with water.

It happened to North Slope Borough Mayor Edward Itta last summer at his family’s fish camp. They had dressed a caribou on the way in and set out fish nets when they got there. Itta’s children opened the lid to the ice cellar and saw nothing but water.

“You can’t do much gathering out there when your natural freezer quits operating,” Itta said later.

In January or July, if you’re in Alaska, there’s a good chance the ground beneath you is frozen solid. There’s a very good chance if you’re in Barrow or anywhere north of the Brooks Range and a pretty good chance if you’re between the Brooks Range and the Alaska Range.

By definition, permafrost is any ground that’s been frozen for at least two years. It can be dry soil or nearly all ice, and it can start an inch below the surface or many yards below. It can go down a few feet or a few thousand.

Permafrost affects how water flows through soils, and it largely determines what trees can grow in a given area. It also poses unique challenges for builders, especially in places where a high ice content causes the ground to change dramatically when the permafrost thaws.

Now, as temperatures warm across Alaska, the temperature of the frozen ground is warming, too. In some places, it’s warmed to its own tipping point of 32 degrees Fahrenheit, at which point it stops being permafrost and starts being water and soil.

“It’s already affecting ecosystems and infrastructure,” says Vladimir Romanovsky, a University of Alaska Fairbanks professor who has studied permafrost in Alaska for the last 16 years. And if projections of rising temperatures prove true, the permafrost is likely to warm and thaw much more in the future.

According to one estimate, fixing all the roads, sewer systems, and public buildings affected by thawing permafrost in the next few decades could cost billions.

The science of frozen ground

Romanovsky monitors permafrost as far away as Mongolia, Greenland and even Antarctica, but he also has a site at UAF that he can see from the window of his office at the International Arctic Research Center.

Romanovsky went there one day last November with two other researchers and an undergraduate student. He wore blue coveralls and winter boots and spoke Russian with two of the others as they worked.

Taking the temperature of the ground is fairly straightforward, Romanovsky explained. You drill a hole, feed a narrow pipe into it, and fill the pipe with a variation of anti-freeze. Then it’s “drop and measure, drop and measure, drop and measure.”

Romanovsky removed the cap from a metal pipe and inserted an electronic thermometer attached to a long tape measure. He let out a meter of tape, checked his watch, and waited.

“With warming in climate, permafrost is warming as well, of course,” he said. “Eventually it will cross threshold and start to thaw.”

According to Romanovsky, most of the permafrost in Interior Alaska is already near that threshold. It’s 30 or 31 degrees.

In general, permafrost exists in places where the annual average temperature is below freezing. But other factors also play a role. Mosses and plant matter help maintain permafrost by insulating the ground from warm air in the summer, and snowcover can actually degrade it by insulating the ground from cold air in the winter.

The mean annual air temperature in Fairbanks is 27 or 28 degrees — at least 4 degrees below the temperature theoretically needed for permafrost. But the insulating snowcover has brought the frozen ground much closer to its tipping point.

At this site, the permafrost is both warming and thawing from the top down. Agricultural researchers cleared the area in the late 1930s, cutting down black spruce and removing any mosses that had built up. In the 70 years since, the permafrost has thawed down about 35 feet. In places nearby that weren’t cleared, the permafrost is still only a few feet down.

But if the ground is changing here because of human disturbance, it’s changing in other places simply because the air is getting warmer. From sites in Barrow, along the trans-Alaska oil pipeline, and in other places, scientists have documented an increase in the temperature of permafrost in Alaska of 2 to 5 degrees in the last 30 years. Records in Barrow show the permafrost was actually cooling in the 1950s and ’60s,when air temperatures were cooler, and started warming in the mid-’70s, when temperatures rose.

By comparing permafrost data with temperature and snowfall records, Romanovsky and others have been able to figure out how permafrost responds to changes in climate. With that understanding, they’ve made predictions about what will happen as the climate warms in the future.

After 45 minutes of “drop and measure,” Romanovsky’s thermometer was 13 meters down — into the permafrost by now.

Romanovsky said he had received a call the day before from someone at the federal Division of Homeland Security asking which communities were most vulnerable to thawing permafrost.

Coastal villages like Kivalina are certainly at risk, he told them. (Thawing permafrost can increase the rate of erosion.) “(But) even part of Fairbanks is one of those communities.”

Scientists have a pretty good sense of what will happen to permafrost if air temperatures rise as expected, Romanovsky went on. But the understanding is general rather than specific, and it’s not enough to let communities plan around what will happen locally.

“It’s really big gap right now,” he said, “and nobody’s jumping on it.”

Infrastructure at risk

A few years ago, the offices of the Barrow Utilities and Electric Co-Op started to shift. One whole wall started “sinking,” said Allen Nesteby, the co-op’s superintendent of operations.

Workers leveled the building, resupported the pilings, and lined the outside wall with insulating blue board and gravel. So far, the repair has worked.

In Barrow, where the average annual temperature is just 10 degrees Fahrenheit, the permafrost is generally well below freezing. (Co-op workers think an unusually high salt content made the permafrost under the building unstable.)

Studies show the layer of ground that thaws out in the summer — the active layer — has not noticeably thickened in the last 15 years in the Barrow area, according to Romanovsky. Summer temperatures, which determine the thickness of the active layer, have not warmed as quickly as annual average temperatures, which determine the temperature of the permafrost.

But there is some anecdotal evidence of a thickening active layer. Mike Aamodt, who ran a drilling business in Barrow for two decades, said he saw the ground thaw significantly between the mid-70s and mid-90s. People who didn’t sink their pilings deep enough would see them shift in the ground.

Nesteby, who oversees the Co-op’s electrical distribution system, said the utility hasn’t had any major problems yet, but has increased its monitoring. Much of the electrical infrastructure, including utility poles and transformers, relies on the permafrost staying frozen.

“This whole are is basically a swamp with very little weigh-carrying capabilities,” Nesteby said recently, “unless you have permafrost.”

Timothy Russell, who oversees the utilidor and water and sewer system, said he’s already had to deal with pipes shifting as the ground settles. In some cases, the shifting has strained connections between water mains and other infrastructure; in other cases, it’s caused wastewater lines to fill partially with standing water.

Russell suspects the problems have something to do with the relatively warm water moving through the pipes. But he also believes the changes in the ground could be linked to changes in the weather.

“We’re having warmer summers now,” he said.

Financial woes

While climate-related changes to sea ice and forests may result in the biggest changes to Alaska’s landscapes, thawing permafrost could have the biggest impact on the state’s pocketbook. Just about everything in Barrow and much of the state’s infrastructure is built on frozen ground and relies on that ground staying frozen. Homeowners, communities, and the state as a whole risk significant costs if permafrost continues to warm and thaw.

Last summer, Peter Larsen and other researchers at the Institute of Social and Economic Research at the University of Alaska Anchorage published a study on how much climate change would add to the cost of public infrastructure.

Researchers estimated that between 2007 and 2030, the state and other public funders could expect to pay an additional $3.6 billion to $6.1 billion, or an extra 10 to 20 percent, to maintain and replace the state’s schools, roads, bridges, and other infrastructure, even with some adaptive measures.

The study relied on climate projections used by the Intergovernmental Panel on Climate Change and considered how thawing permafrost and increased flooding and erosion would affect infrastructure. Most of the increased costs came from the impacts of thawing permafrost on roads, runways, and water and sewer systems.

Dan White, director of the Institute of Northern Engineering at UAF, described the study as a “good first attempt.” The assumptions used in it need to be refined as more information is gathered, he said.

But White agrees that changes in permafrost could have significant impacts on infrastructure in years to come.

Builders have figured out ways to maintain permafrost below infrastructure — by raising the infrastructure off the ground, for instance, or using thermosyphens that actively draw heat from the ground. (When homes start to tip in Fairbanks from thawing ground, it’s because of the furnace, not the climate, White says.)

As the climate warms, it will become that much harder — and more expensive — to keep the ground frozen. Existing technologies are capable of handling the changes, according to White, but in some cases, retrofitting infrastructure will probably cost more than tearing it up and starting over.

“There certainly is a risk to infrastructure that’s been designed on a design climate that doesn’t hold,” he said.

In a sense, the state’s economy depends on those technologies working — at least in the case of the trans-Alaska oil pipeline.

The engineers who designed TAPS knew about permafrost, and they designed for it.

In places with permafrost, they lifted the pipeline off the ground and used vertical supports with thermosyphens, or heat exchangers. In places without permafrost, or where thawing the permafrost wouldn’t cause the ground to shift, the pipeline was buried underground.

Engineers knew that by clearing the trees and plant matter from the pipeline corridor, they would allow more heat into the ground and start thawing the permafrost, explained Mike Metz, a consultant who helped in the design.

South of the Brooks Range, where the permafrost was relatively warm already, they figured it would thaw down about 30 feet in 30 years. Thirty years passed in 2007, and their projections turned out to be largely right.

To keep the pipeline supports stable, engineers designed them to maintain a bulb of frozen ground around each one. They figured if they could remove enough heat from the ground in the winter, they could keep the ground around the columns frozen year-round. The math said they’d need one ammonia-filled heat exchanger per support, but just to be safe, they put in two.

“This was the first time it had ever been done,” Metz said.

The system worked, and so far, the oversized heat exchangers have handled the increase in air temperature.

But according to Metz, it’s unclear how much longer that will be the case.

“We know that we have a lot of excess capacity designed into the heat pipe system,” he said, “but right now we don’t know exactly how much.”

The Alyeska Pipeline Service Co. closely monitors the pipeline.

A changing landscape

In northwest Alaska, Jim Dau is already seeing landscapes change as the ground warms.

For the last 19 years, Dau has worked as a wildlife biologist for the state’s Department of Fish and Game out of Kotzebue. He mostly studies caribou, and he spends a lot of time flying a small plane over the tundra.

A few years ago, Dau started seeing places where the ground was giving way — collapsing into the ocean or a river — or simply folding up like an accordion.

He called them “slumps.”

At first there were just a few, but now they’re common.

“Just in the last three or four years, what I’m seeing out the window of the Supercub is really different,” he said last year.

According to Romanovsky, the slumps are probably caused by ice-rich permafrost thawing from the top down. The ice melts and saturates the active layer, which then slides easily on the permafrost below.

In large areas of the state, thawing permafrost is already changing landscapes and hydrology, in turn affecting plants and animals. In other places, warming of the permafrost has made the frozen ground more susceptible to thawing from disturbances like wildfires.

“It’s hugely important,” says Larry Hinzman, a professor of hydrology at UAF and director of the International Arctic Research Center.

In 2004, when it was unusually hot and dry, there were landslides all across Alaska, Hinzman said. In one case, a huge mass of tundra collapsed into the upper Selawick River near Kotzebue, nearly shutting off the river and dirtying the water with silt for miles.

Shallow “thermokarst” lakes are forming on the North Slope, around Fairbanks, and elsewhere as permafrost thaws and the ground settles. Birch trees are drowning on the Tanana Flats as thawed surfaces fill with water.

In other places, surface water seems to be draining through degraded permafrost that no longer serves as an impermeable barrier.

Dau has seen whole lakes disappear from the window of his plane. A big one near Kotzebue drained in a matter of days, he said, “Like pulling a plug on a bathtub.”

According to Romanovsky, the water is probably escaping laterally rather than straight through the permafrost.

Permafrost’s contributions

Thawing permafrost also has the potential to speed up climate warming by releasing large amounts of methane, a strong greenhouse gas. As the ground thaws, organic matter frozen in it starts to break down, creating the gas, which can then escape into the air.

For the last eight years, Katey Walter has been studying the release of methane from arctic lakes, first as a graduate student at UAF and now as an assistant professor there.

She says it’s still unclear whether more gas is escaping as temperatures warm and permafrost thaws, but adds that that seems to be the case.

In April, the National Oceanic and Atmospheric Administration reported that atmospheric methane increased in 2007 after holding steady for nearly a decade. A NOAA scientist said it was “too soon to tell” if thawing permafrost was to blame, but added that the agency was watching closely.

The amount released already is impressive. Walter measures methane bubbling up from “hotspots” under the water and estimates that a few cubic feet of gas per day escape from a typical pond in Fairbanks.

The gas can be tested in a lab, but the easiest way to tell if it’s methane is to see if it burns.

One afternoon last November, Walter and two graduate students scanned for bubbles in the ice on a pond near Fairbanks and put matches to any they could find and break open. Bright flames leapt up from the ice.

In one spot, a tower of fire shot 20 feet into the air.

Walter jumped back to avoid the flame.

Not everything about permafrost is so dramatic.

The warming of the frozen ground is mostly a story of slow temperature changes and thawing soils. But it’s also a story with tipping points, where slow changes can suddenly have dramatic impacts.

With permafrost, 31 degrees can mean frozen ground and 32 can mean dead trees, drained lakes, and strips of tundra folded up like an accordion.

A small change can turn a working ice cellar into one that’s filled to the top with water.

According to Romanovsky, most of the permafrost in Alaska is still relatively stable.

But the temperature of it is getting very close to the threshold of 32 degrees, he said, and if the projections for climate warming prove true, a huge area of the Northern Hemisphere will likely cross that threshold in the next 20 or 30 years.

“And then the picture will be very different.”

Next: The current and expected impacts on fish, including warming waters and increased disease.