Creeping Landslides
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Creeping Landslides Threaten Alaskan Highway

Bittersweet Irony for Alaskan Oil

(Published by The EarthSphere Blog. Cover Image: Warped Highway by WM House; ArcheanArt)

Some stories are too quirky to ignore. One of those stories is a slow-moving, underground, zombie landslide digesting a critical Alaskan highway. Temperatures are rising faster in Alaska than across most of the planet. Rapid Arctic warming is and will continue to be an area of climate change concern. But we get unexpected consequences as we move down the path to a warmer future. Zombie landslides are one of these consequences. I am using the term zombie in the correct sense, meaning they have come back from the dead. Now, these underground debris flows threaten key parts of Alaska’s economic infrastructure.

These flows are tearing through Dalton Highway, one of Alaska’s key roadways, a 414-mile stretch of road connecting the central areas of the State, near Fairbanks, with Prudhoe Bay in the north. The term ‘tearing through’ is a bit of a stretch since the flows only travel 20 to 30 feet per year or less. But 50 years ago, they were not moving at all. The debris flows were frozen in place and anchored to bedrock. They weren’t deemed a threat by the engineers who first surveyed the highway. Now they have come back to life thanks to global warming.

These debris flows are composed of sand, rocks, gravel, and trees mixed into thawing permafrost. One of the flows, poetically named ‘Lobe A,’ is about 4,000 feet long, 600 feet wide, and 65 feet deep. The lobe was traveling about 16 feet per year in 2013, and it had accelerated to a 32-feet-per-year pace by 2020. Engineers can’t build on it or over it, so they have recently moved the highway slightly to the west, postponing the road’s ultimate demise.

Anatomy of a Zombie Landslide

The problem is larger than a single landslide. The State Highway Department counts 43 debris flow lobes along the Dalton Highway. These features have their origins in events from thousands of years ago as the last ice age ended. During periods of heavy glaciation, the glacial ice carved out scoops and bowl-shaped depressions along westward sloping bedrock. Glacial retreat after the last ice age left these depressions exposed, and they slowly filled with rock, gravel, sand, tree remains, and other debris. These materials were sealed in place by frozen permafrost. But now, as the permafrost melts, the water-logged debris lobes are moving downslope under the influence of gravity.

Even as late as the early 1970s, when geologists first mapped them, the entire debris mass was solidly locked up and anchored. The lobes were considered inactive and immobile, posing no threat to the highway or the oil pipeline constructed parallel to it. This pipeline carries crude oil from the Prudhoe Bay oil fields to refineries and other markets, where it is processed into usable fuel.

When the highway and oil infrastructure were built, climate change was a vague and poorly understood concept. There was no fundamental understanding of the approaching storm or the rapidity with which the world around us would change in response to global warming. We understood how burning fossil fuels added greenhouse gases to the atmosphere, but we didn’t understand the magnitude of the problem.

By the time science developed a more comprehensive understanding of global warming, the debris deposits were awakening from the dead and coming back to life. Average temperatures have only increased since then, and now these higher temperatures hasten the rate of permafrost melt, accelerating the downslope speed of the debris lobes.

Bittersweet Irony

Oil producers and transporters on Alaska’s north slope are now facing a bittersweet irony. The oil they pumped for decades made significant contributions to global warming. Greenhouse gases, released as their fossil fuel burned, have helped raise global temperatures and contributed to a world where Alaska’s average temperature has risen three times faster than the rest of the world.

The trans-Alaska Pipeline is the only conduit for transporting crude oil from the North Slope to the global markets. This pipeline, built in 1974, parallels the Dalton Highway. While the highway is the first infrastructure the zombie landslides will devour, the pipeline also lies in the direct path of these slow-moving, unstoppable flows.

In a bit of environmental drama, heat caused by North Slope oil has awakened these large underground debris flows, which now threaten to shut down the pipeline. We must reap what we sow. The activation of these debris flows is a direct result of global climate change.

The Dalton Highway is a lifeline for North Alaska. It serves remote Arctic villages and provides the crucial supply chain link to the North Slope oil fields. The pipeline is a vital part of Alaska’s economy, moving 20 million gallons of crude oil a day to market. The loss of the highway and pipeline would deal a heavy blow to the State. What was once considered an alarmist joke is now a severe problem, with no solution in sight.

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Arctic Warming Three Times Faster Than The Planet: Report (by Pierre Deshayes; PhysOrg)

Unleashed by Warming, Underground Debris Fields Threaten to ‘Crush’ Alaska’s Dalton Highway and the Alaska Pipeline (by David Hasemyer; Inside Climate News)

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.