Vavilov Ice Cap Transitions Into a Fast Moving River Of Ice; Arctic Permafrost Thaw Underestimated
December 30th 2019
The Agashashok watershed in Noatak National Preserve (National Park Service)
By Pakalolo (of the Daily Kos community)
The annual meeting of the American Geophysical Union was held on December 9 in San Francisco. There should be a lot of updated information on climate change released to the public in the coming weeks.
Two items discussed was permafrost and glaciers, including those from Greenland and Antarctica. The other is a new form of permafrost thawing not included in current climate models.
E&E News reports on the astounding change taking place at Vavilov Ice Cap
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.
"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."
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.
rom the abstract published in the AGU Research Letters: The Possible Transition From Glacial Surge to Ice Stream on Vavilov Ice Cap
A glacier surge is a sudden speedup of glacier flow coinciding with a large advance of the ice front. Some glaciers surge periodically every 10–100 years, and so surge mechanism is thought to be independent of climate change. However, some recent surges have evacuated so much ice that another surge is unlikely to occur in the same place again. A glacier surge at the Vavilov Ice Cap, Russia, is one of these cases. Since 2013, the glacier has drained more than 11% of the ice basin (9.5 Gt) into the ocean. After the initial surge in 2013, the glacier still retains fast flow at around 1.8 km/year, an unusually high and long‐lasting speed for a glacier surge. To understand the future of the surge, we use satellite images to calculate surface elevations and ice speeds, and analyze their change over time for the glacier. The results reveal that the glacier now physically behaves more like an “ice stream,” a stream of fast‐flowing ice within an ice sheet, which can probably flow at high speed for a long time and drain ice efficiently. This is the first documented case of an ice stream‐like feature ever being formed.
New results relying on five decades of satellite observations show extensive changes to glaciers at the Earth's north and south poles, a result of global warming. The below video is on Alaskan glaciers.
From the University of Alaska Fairbanks — The Grand Reveal
“This green line looks like the death of permafrost — it’s flatlining,” Louise Farquharson said to an audience of a few dozen scientists.
Her quiet voice came through speakers over the muffled clicking of keyboards and occasional coughs in a dimly lit room at the 2019 American Geophysical Union fall meeting in San Francisco.
She was showing a graph describing her newest research findings on one of the most important, and ignored, parts of the frozen Earth.
Her reserved tone hid a bombshell message — by 2035 permafrost thaw may continue on its own, disregarding the processes that have kept it frozen for thousands of years.
snip
This factor is called talik, thawed zones in permafrost areas.
The mixture of wet, frigid dirt is commonly associated with Arctic thermokarst lakes that form when enough ice-rich permafrost thaws to create a body of water.
The talik beneath these lakes significantly contributes to the thawing process. Just as icewater melts faster than a lone cube of ice, the waterlogged ground accelerates thawing of the permafrost around it.
Normally talik has been thought of as limited to the areas just below and around thermokarst lakes, but Farquharson’s work shows they are much more extensive.
Farquharson and her collaborators, including Vladimir Romanovsky, also at the Geophysical Institute, observed substantial evidence from 28 sites across Alaska showing these taliks are larger, and extend deeper in the ground, than previously thought — even in many areas scientists didn’t know it existed.
This could have dramatic effects on permafrost, making previous thaw forecasts and estimates of subsequent carbon release pale in comparison to what is coming.
“You look at your lake distribution of taliks and how much of the landscape that accounts for, and then you take that number and you spread it across pretty much the entire landscape in Interior Alaska,” she said.
“We’re going to basically change the calculations for global carbon emissions.”
To maintain permafrost, the ground has to be exposed to frigid air for a period of time before snow falls. During warmer years or years when snow falls earlier, the snow insulates the ground while it’s still warm, like a down comforter trapping heat in the ground. This promotes thaw.
For the past two to three years, Farquharson has seen more thaw than freeze, which means more talik. However, this is still tied to snowfall. If enough talik develops, even snowfall won’t halt thaw.
Posted with permission