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Icy Debris Blobs Are Creeping Closer to Alaska's Only Road to the Arctic

Twenty three “frozen debris lobes” are nearing Alaska’s Dalton Highway, and climate change could be to blame.

by Sarah Emerson
Nov 30 2017, 3:00pm

Alaska's Dalton Highway, near Atigan Pass. Image: Flickr/Peter Waterman

Alaska’s main artery to the Arctic, the 414-mile-long Dalton Highway, is being threatened by rapidly thawing "landslides," according to a report from Arctic Now.

Twenty three permafrost features, called “frozen debris lobes,” are steadily creeping toward the remote highway. Panned out, these geohazards resemble mudslides. One of them, which is set to reach Dalton Highway by 2022—now 86 feet away from the road—has been approaching 1.5 centimeters each day, according to a team of researchers at the University of Alaska Fairbanks.

The slurry of materials comprising a frozen debris lobe. Screenshot: University of Alaska Fairbanks

But, up close, these moving masses are a mix of boulders, silt, and organic matter, with below-freezing liquid cores. They sit atop permafrost, a frozen layer of carbon-sequestering soil, which allows them to slide along the ground, slowly but surely. Some have exceeded 328 feet in width, 65 feet in height, and 3280 feet in length, found a 2012 study published in Natural Hazards and Earth System Sciences.

“This is a big carpet roll of organics,” said Margaret Darrow, a geological engineer and associate professor at the University of Alaska Fairbanks Mining and Geological Engineering Department, in a video about Alaska’s frozen debris lobes.

It’s “acting like a bulldozer, and just pushes up, and rolls it up,” she added, referring to the way lobes move the environment around them.

While frozen debris lobes are naturally occurring, climate change is likely worsening them. In Alaska’s Brooks Range, where the 23 slides are situated, warming temperatures are already having large-scale effects. Alpine glaciers have receded over the past half-century, for example. All Brooks Range glaciers will vanish in 80 to 100 years, if ice loss accelerates along current trends, according to the US Fish and Wildlife Service.

“When the temperatures are warmer, it moves faster,” Darrow told BBC News in 2015.

“I would project that if temperatures warm it will move faster, and there's a relationship between temperatures and precipitation. I would assume that with rising temperatures we will see more rainfall and if that is the case they will move faster.”

Screenshot: University of Alaska Fairbanks

The threat of melting permafrost is especially dire in Alaska’s Arctic region. More than 65 feet underground, in the Brooks Range, temperatures have risen 3 degrees Celsius in the last few decades, found Vladimir Romanovsky, a permafrost researcher at the University of Alaska Fairbanks. Temperature increases were even more drastic near the surface.

In the near term, however, despite climate change’s palpable presence, transportation planners aren’t allowing Dalton Highway to be overtaken.

Next fall, a particularly “at-risk” section of the highway will be moved 400 feet to the west, reported Arctic Now. A $21 million contract was also awarded by Alaska’s Department of Transportation and Public Facilities to reconstruct 25 miles of highway, which have been hampered in recent years by climate change-related flooding.

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