https://www.scientificamerican.com/article/a-russian-ice-cap-is-collapsing-it-could-be-a-warning/

High in the Russian Arctic, in the chilly waters straddling the Kara and Laptev, an 84-billion-ton island ice cap is projectile vomiting into the sea. Scientists say it could hold useful clues about what to expect as the world continues to warm.

The Vavilov Ice Cap, nestled in Russia's Severnaya Zemlya archipelago, suddenly started to surge forward in 2013. This is not an uncommon event for glaciers — every so often, pressure will build up behind the ice and cause it to temporarily slip forward. These surge events can last anywhere from a few months to a year or more, and they'll typically stabilize on their own.

But in 2015 — two years after the surge started — the Vavilov Ice Cap was still going. By then, it was moving faster than ever, flowing forward at a rate of about 26 meters per day and dumping 4.5 billion tons of ice into the sea over the course of a single year.

In total, Vavilov has lost about 9.5 billion tons of ice in the last six years.

Scientists monitoring the ice cap's progress say it's moved beyond a simple glacial surge. The rush of ice seems to have transitioned into a phenomenon known as an "ice stream," a long-lasting, fast-moving flow of ice out of the glacier and into the surrounding landscape — or, in this case, the sea.

Scientists know ice streams exist in frozen places around the world, including the Greenland and Antarctic ice sheets. But according to a new paper describing the events at Vavilov, this is the first time researchers have documented an ice stream's formation from the very beginning.

Now that they've seen how it happens, the researchers say their observations may hold clues about the future of the world's glaciers as global temperatures rise.

"Now we know these ice caps could be more unstable" than previously believed, said lead study author Whyjay Zheng, a doctoral student at Cornell University. "We may possibly have to revise our future sea-level rise, considering this."

Even when they appear to be stationary, glaciers are typically flowing forward — just so slowly it's barely noticeable. There's a reason for the phrase "moving at a glacial pace." Until 2013, Vavilov Ice Cap was likely inching forward at an imperceptible rate.

The researchers believe the ice first began to surge when it pushed past a mound of sediment on the landscape that had previously served as a barrier holding it back. When this happened, it slid onto a smoother patch of bedrock and slipped forward.

"You used to have a gate that constrained the ice, and then you lose this gate," Zheng said. "So all of this ice at a higher place just collapsed down into the ocean."

The Vavilov Ice Cap is on a Russian island in the Arctic Ocean. NASA