Is unprecedented movement from a High Arctic ice cap a sign of things to come, or just a weird event?
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| © CIRES the rate of glacier movement |
By Kat Eschner, Popular Science
A researcher watching Russia’s largest High Arctic glacier was surprised when his gaze shifted to its nearby neighbor. What he saw there raised questions about how glaciers work—and what we may be facing as the world warms.
“I kept on seeing this other ice cap in the southern part of the scenes I was looking at via satellite,” says University of Colorado geologist Michael Willis. He was studying the Academy of Sciences Glacier, Russia’s largest, but what really caught his eye was the nearby Vavilov Ice Cap. It was doing something totally unexpected, he says: moving, and quickly. The ice cap—the term refers to a type of glacier, of which “polar ice cap” is a subset—is of a kind that’s supposed to be very stable. “This kind of ice cap shouldn’t be displaying this kind of behavior,” Willis says.
In this instance, though, the ice cap was practically galloping along: “surging” at a pace of 82 feet per day in 2015, as Willis and his colleagues found. Previously, its average speed was just about two inches per day. Using a combination of historic data from an earlier study, and data from two current satellite information systems, they traced the glacier’s movement and its degree of ice loss.
All glaciers “move” as ice freezes or melts on their edges, shifting their location. But it’s not just the ice visible from the air that’s important to this process—things happening deep under the surface have influence as well. One of these unseen processes might be behind the dramatic movement, says Willis. Over the period of study, he says, the bottom of the ice changed from “rough and sticky,” meaning stable, to “slick,” meaning there’s water down there lubricating the ice cap’s movement. The presence of water under the ice suggests the existence of a slightly warmer layer—or water somehow getting in from the surface.
Little is known about how exactly this might happen, Willis says, and they’re still trying to figure it out. “This is strange. It was a surprise to see it. And it’s not been really simple to explain it.”
This surprise matters—especially if it’s going to happen again elsewhere. Current climate models don’t take this kind of surge into account. But high-altitude glaciers of the same type of the Vavilov Ice Cap hold the potential to contribute about a foot to sea level rise. That means that all of the water currently held in these glaciers as ice, if it was melted back into the ocean, could potentially cause sea levels to rise by a foot.
“What we don’t have is a good enough satellite image catalog to know if these are kind of one-offs or this is something cyclical,” says University of British Columbia glaciologist Christian Schoof. Schoof points to another study of a glacier in Svalbard that shows a similar process. That study is in pre-print and unlikely to be published, but the data appears to be solid, he says.
Unlike other climate sciences—oceanography, for instance—there’s not a lot of great historical data on what glaciers in the world’s remote parts have been doing over the course of the last few hundred years. But Willis’s new paper might point to something historically notable. In general, glaciers like the Vavilov Ice Cap are predictable They’re machines trying to balance the input of snow and the output of climate influences on the ice, and generally, in the absence of forces changing the climate, quite stable, he says. “These surges are interesting because they don’t do that,” he says, which raises some questions about how we currently model this kind of glacier. Current predictions about melting may not be taking these kinds of movements from the glacier into account—or, if they’re cyclical, Schoof says, can’t say what will happen to the cycle in the presence of climate change.
In the case of the Vavilov Ice Cap, Willis says he’d be “hesitant” to link what happened directly to climate change. But “the sheer fact that it can do this is eye-opening,” he says. “We can call it an anomaly, but if it’s happened in one place it can happen elsewhere too.”
“This is a great example of something that can happen to ice sheets and to glaciers that we don’t understand particularly well,” Schoof says. That understanding may prove crucial to predicting things like sea level rise and glacier melt.
Willis and his colleagues started thinking about how to model the behavior of the Vavilov Ice Cap during their work on this paper, though that is not yet published. They hope to continue working on modeling for this kind of dramatic event. Schoof says that’s good, but also calls for more observation of the world’s High Arctic glaciers to help us better understand—and predict—their behaviors.
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