This year, the extent of Arctic sea ice reached its third-lowest point since scientists began keeping satellite records more than 30 years ago.  In fact, the last four years have been the four lowest years on record, and, according to the National Snow and Ice Data Center in Boulder, CO, Arctic sea ice is continuing a long-term decline with ice that is younger and thinner than in previous decades.

There's no question that the Arctic has been warming in recent years, and data shows that it's warming twice as fast as the rest of the planet.   Scientists say that thawing polar regions, and the loss of sea ice and permafrost that follows, will likely have global consequences in the not too distant future.

I traveled to the Arctic Circle in June, and joined University of Fairbanks researcher Andrew Balser on the North Slope of Alaska's Brooks Range, about 140 miles south of the Arctic Ocean. Balser's research takes him into grizzly bear country, and he was willing to take me along because, in theory, it was safer that way.   Once the helicopter dropped us off in the middle of the wide-open tundra, a horde of mosquitoes descended, but Balser seemed impervious to them. He was dressed in canvas overalls that looked like they'd never seen a washing machine.   As it turns out, that's part of his strategy. 

"For some reason it always seems like the person who is the most bathed and well-scrubbed is the one that gets it," Balser explained, lending me his head net.  "I'm not sure why. It pays to be a grubby field worker out here."



The Air Conditioner for the Planet

Balser is here studying thermokarsts, which are big gullies that sometimes form in the Arctic when the underground layer of frozen soil, called permafrost, thaws, and the ground above it either caves in or slides down a hillside.  Thermokarsts alter the landscape, creating mysterious-looking depressions in the tundra, and jagged scars on hillsides.  They dump sediment into nearby streams, sometimes dramatically altering habitats for fish and other aquatic organisms, and they've even been known to swallow the occasional house.

But thermokarsts are part of a much larger issue, too -- one with global consequences.  They've been increasing in frequency in parts of Alaska, and scientists say this is no coincidence.

"Thermokarsts are very small, so it's easy to say, ‘Yeah, who cares about thermokarsts?'" said Josh Schimel, a soil ecologist at UC Santa Barbara, "but the Arctic is the air conditioner for the entire planet, and the air conditioner is breaking."

Scientists say that if you add up all the carbon that's circulating in the atmosphere right now in the form of CO2, methane, and other greenhouse gases, there's at least that much more locked up in permafrost. And as temperatures rise, the permafrost is thawing.  Which means organic matter that's been frozen for thousands of years in some cases, is decomposing and releasing that carbon, much of it as greenhouse gases.  More carbon in the atmosphere means more warming, which means more thawing permafrost. It's a vicious cycle known as a "positive feedback," and it has potential consequences for the entire global climate system, including California.

"The warming contributed by CO2 and methane from these tundra ecosystems will lead to warming in CA, with hotter days in LA, and those of us who live in those areas know just what a really bad hot day means," said Schimel.  "It will contribute to the loss of the snowpack in the Sierra and water problems."

Digging for Permafrost, and Clues

On Alaska's North Slope, Balser is looking at just one piece of this thawing permafrost puzzle. He's trying to figure out why thermokarsts form where they do.

We mucked our way across a stream and then hiked several hundred meters up from the valley floor, across the uneven tussock to the top of a good-sized thermokarst, a jagged depression extending down the hillside about five feet deep and wider than a tennis court. There, Balser picked a spot near the top, unpacked a thin shovel, and started digging into the sidewall of the thermokarst. After 15 minutes or so, he hit something frozen. He could tell by the sound and feel of the shovel.

"Oh, wait, there it is, there's permafrost," he said, pointing at the frozen soil he had just exposed.  "So, check it out, if you take this shovel and hit rock, you get that ring in the shovel.  If you hit permafrost, it's kind of like a dull thud."

Balser kept digging and soon we could see the layers of silt and gravel, unfrozen on top, with permafrost below.

"Yeah, this is sweet," said Balser.  "This is really good actually.  It takes a real geek to get excited about this."

Balser spent the summer digging into as many thermokarsts as he could, noting their physical characteristics and those of the surrounding landscape and vegetation.   He'll use his data to construct a map that will help predict where in Alaska they are likely to show up as temperatures warm.

The Tipping Point

Breck Bowden of the University of Vermont heads up large thermokarst research project in Alaska.  He says there's no scientific debate about the melting point of ice.

"In environmental sciences, it's often difficult to say where a tipping point is. You know, we hem and haw about where it's going to be," Bowden said.   "This one, there's no argument," he explained. "Zero degrees centigrade is a tipping point, you know?  You go beyond that and it tips, okay?  And the trajectory is clear."

According to Bowden, half of the permafrost in the Arctic could thaw in the next 50 years, releasing enough carbon to set into motion some irreversible changes.

It's too soon to tell how much thawing permafrost has already contributed to increases in greenhouse gases in the earth's atmosphere. Methane levels have tripled over the last two centuries. They leveled off during the 1990s but started climbing again in 2007. And while there's far less methane than CO2 in the atmosphere, methane is at least 20 times more efficient at trapping heat, depending on how it's measured. Meanwhile carbon dioxide levels have been rising, and are already well above what many scientists say is a healthy level for sustaining life as we know it.  A sudden release of even a portion of the carbon that's stored in the frozen soils of the Arctic could push the region, and the globe, past a tipping point.

"Why should someone who's living in Alabama or Nigeria or the Philippines care about what's going on the Arctic?  Well, they should worry a lot," said Bowden. "What happens here is going to affect everything in the globe."

And scientists here in the Arctic warn that once some of those effects get underway, they may be beyond our control.