Beneath Alaska: Permafrost warms to new depths

ANCHORAGE, Alaska (KTUU) - From the very air we breathe to the soil beneath our feet, climate change is shaping the last frontier in ways both visible and hidden. Even just a few feet below the surface, Alaska’s soils are warming at depths few ever see.

A new study published this year in the journal Frontiers in Climate details just how significant soil warming across Alaska, in both permafrost and non-permafrost regions, have occurred over a nearly 30-year period.

Lead author of the study Erin Oliver used data from 43 weather stations across Alaska, using information from 1997 to 2023.

“It was really surprising to see,” Oliver said.

She stated how quickly it was warming by pointing out the monthly data. During the study, soil temperature was measured at a depth of 5 centimeters below the surface down to 120 cm, or about four feet deep for the continuous permafrost region of Alaska.

“It averaged in like the continuous permafrost region like 0.6° Celsius per decade," Oliver stated.

Oliver said that within that dataset, there were months were it was warming on average three to four degrees per decade.

The study did face some challenges, with Oliver pointing to few soil probes and uneven coverage of data across Alaska. Alaska Climate Specialist Rick Thoman echoed those statements.

“We have really limited data overall on ground temperatures in the state,” Thoman said. “So trying to squeeze as much out of what we have, I think, is certainly an important goal.”

Alaska is notorious for having data gaps across the state, with any data critical in a state with more extreme weather events and one of the fastest warming areas of North America.

Despite the lack of data, the 2024 Arctic Report Card backs up the study and pointed to a thawing permafrost and a shift in the Arctic tundra from a net carbon sink to a net carbon source.

“When we add in things like thawing permafrost plus the effect of Arctic Wildfires, we have probably already crossed that threshold,” Thoman said.

That threshold being the question of the Arctic becoming a carbon source instead of a sink: Thoman said this is a major milestone, and that while Alaska is only about 5% of the Arctic, it is contributing to the issue as much as the rest of the Arctic.

“We could lose more roads, more buildings, and then it also could release more carbon into the air,” Oliver stated, “which could then just make warming faster.”

But the effects of a warming Arctic aren’t uniform across Alaska. The study found that soil temperatures are changing differently depending on the region and the season.

“In the North Slope region, the soils were warming the fastest in winter and less so in summer,” Oliver said. “Whereas the Southcentral region, the soils were warming the fastest in summer rather than winter, mostly due to snow.”

Snow on the ground actually contributes to warming due to a snow blanket effect, much like a comforter or blanket traps warmth in on a cold night.

“It traps the heat more because the heat can’t escape through the snow as it can when there’s less snow or no snow,” Oliver said.

Thoman added that seasons are rapidly changing in Alaska, which gives many areas a smaller window for snow compared to years past.

“What we’re seeing in most places, except on the North Slope, is that the snow season is being compressed,” Thoman said. “So we’re getting the snowpack in the autumn established later in the year and in many areas, we’re seeing the snowpack melt off in the spring earlier.”

He says that in between all that — or what he calls midwinter — many places are actually seeing an increase in snow. He stated the total snowfall is not changing in most places by a lot, but the season itself is being deeply compressed.

“That’s important for the soil response,” Thoman said. “Later establishment of that snowpack in many areas of mainland Alaska would mean perhaps the soil starts to freeze.

Even then, changes are already being seen and felt across the state.

“At Point Lay, where the depth that the ground thaws in the summer has increased so much,” Thoman said, “many buildings in the community are now, they’re tilting infrastructure. Utilidor supports are becoming cockeyed as the ground basically thaws out from underneath them.”

No place across Alaska is exempt from these effects, but Western Alaska remains fairly vulnerable, with Newtok being an example of what’s to come.

“Nothing happens and then all at once ... in two hours, 100 feet slough off.”

Thoman said on the earth time scale, this is reversible, but on the human time scale, it’s going to be very difficult to reverse.

Oliver sad that even with the limited data, information like this is key for planning.

“Having the data is really helpful in planning,” Oliver said. “Particularly around things like infrastructure.”

She goes on to say that the data would be very useful in seeing what regions are warming the fastest and calculate the timelines on when something must be done. A 2025 study pointed to damage costs in Alaska are projected to double as infrastructure damage occurs due to permafrost thaw. The study estimated that building and road losses due to permafrost thaw could cost Alaska $37 to $51 billion by 2050.

“People that live in areas with permafrost are experiencing it all the time,” Thoman said. “It’s costing the state money just to keep things where they’re at. All the money DOT is spending is repairing the same sections of roads.”

Thoman said that is money going to fix the problem and not to something else.

With thawing permafrost comes subsiding land in some areas of Alaska.

“Land subsiding a foot may not seem like very much,” Thoman said. ”But when you’re only a few feet above the high tide line, that can make all the difference."

A difference that for many could force relocation of their villages or homes, as the last frontier becomes a changing frontier in a land of new extremes and a warmer world.

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