Admin correction: the title of this story, “The Greenland ice sheet is past the point of saving, warns the AGU,” has been edited to reflect the content of the statement by the AGU, linked below.
"It would be some consolation for the feebleness of our selves and our works if all things should perish as slowly as they come into being; but as it is, increases are of sluggish growth, but the way to ruin is rapid." Lucius Anneaus Seneca, Letters to Lucilius, n. 91
I wanted to prepare diaries on each topic below, but climate breakdown is forcing my hand to prepare a summary of Greenland News instead. The climate breakdown has begun; that is not my opinion but a statement from the United Nations.
American Geophysical Union
Based in part on carbon emissions, a new study using simulations identified two tipping points for the Greenland Ice Sheet: releasing 1000 gigatons of carbon into the atmosphere will cause the southern portion of the ice sheet to melt; about 2500 gigatons of carbon means permanent loss of nearly the entire ice sheet.
Having emitted about 500 gigatons of carbon, we’re about halfway to the first tipping point.
“The first tipping point is not far from today’s climate conditions, so we’re in danger of crossing it,” said Dennis Höning, a climate scientist at the Potsdam Institute for Climate Impact Research who led the study. “Once we start sliding, we will fall off this cliff and cannot climb back up.”
To more comprehensively model how the ice sheet’s response to climate could evolve over time, Höning’s new study for the first time used a complex model of the whole Earth system, which includes all the key climate feedback processes, paired with a model of ice sheet behavior. They first used simulations with constant temperatures to find equilibrium states of the ice sheet, or points where ice loss equaled ice gain. Then they ran a set of 20,000-year-long simulations with carbon emissions ranging from 0 to 4000 gigatons of carbon.
From among those simulations, the researchers derived the 1000-gigaton carbon tipping point for the melting of the southern portion of the ice sheet and the even more perilous 2,500-gigaton carbon tipping point for the disappearance of nearly the entire ice sheet.
Methane beneath the Greenland ice sheet to intensify climate warming, scientists warn. A unique project to access the ice-sheet bed hopes to expose the scale of the danger.
Interesting photos and quotes from Elizaveta Vereykina of the Barents Observer on an ongoing study to determine how much methane from vegetation is under the Greenland Ice Sheet. The study area is a small outlet glacier, Isunguata Sermia, that shows evidence of methane from below the ice margin.
The Greenland ice sheet is the biggest contributor to global sea level rise at the moment. And it’s set to accelerate. So we need to understand how fast that is happening. It already looks like it will be a problem for low-lying coastal regions around the planet in the next 80 years”, Alun Hubbard - Professor of Glaciology at UiT, told the Barents Observer.
When glaciers advanced in the past, they buried vegetation and soil, trapping organic carbon beneath the ice. Over time, microbes may have transformed this carbon into greenhouse gases”, expedition member Petra Klimova, microbiologist from Charles University in Prague, told The Barents Observer.
The preliminary seismic data we collected seems to confirm our suspicions that layers of sediment are lying under the ice here - more than 150 metres thick in fact - and importantly the potential envrionment for methane production that we have been on the hunt for”, explained Henry Patton.
That 150 meters noted in the last quote is 492 feet of thick compressed prehistoric vegetation from the Pleistocene. It is simply mindboggling in scale and is a life-ending threat.
From NASA - What a Glacial River Reveals About the Greenland Ice Sheet
With data from a 2016 expedition, scientists supported by NASA are shedding more light into the complex processes under the Greenland Ice Sheet that control how fast its glaciers slide toward the ocean and contribute to sea level rise.
On the surface of the ice sheet, bottomless sinkholes called moulins can funnel meltwater into the base of the ice. As that water reaches the ice sheet’s underlying bed, it can make the ice detach slightly and flow more rapidly.
Glaciers that slide faster can eventually lead to the ice sheet melting a bit faster than expected, also increasing the amount of ice calved into the ocean. With a vast surface area roughly the size of Mexico, Greenland’s melting ice is the largest contributor to global sea level rise.
In a new study, published April 5 in Geophysical Research Letters, the authors concluded that the one important factor influencing the speed of a sliding glacier in southwest Greenland was how quickly water pressure changed within cavities at the base of the ice where meltwater met bedrock.
“Even if the cavities are small, as long as the pressure is ramping up very fast, they will make the ice slide faster,” said Dr. Laurence C. Smith, a professor of environmental studies and Earth, environmental, and planetary sciences at Brown University in Providence, Rhode Island.
It’s the first time observations directly from field research show how changes in the volume of water under the Greenland Ice Sheet drive the flow velocities of a glacier.
The findings contradict a long-held view about ice sliding velocities and water stored under a glacier known as steady-state basal sliding law, which has helped scientists predict how fast ice sheets will slide based on the total volume of water underneath the ice.
Abstract of An Early Pleistocene interglacial deposit at Pingorsuit, North-West Greenland
At the Pingorsuit Glacier in North-West Greenland, an organic-rich deposit that had recently emerged from the retreating ice cap was discovered at an elevation of 480 m above sea level. This paper reports on macrofossil analyses of a coarse detritus gyttja and peaty soil, which occurred beneath a thin cover of till and glacifluvial deposits. The sediments contained remains of vascular plants, mosses, beetles, caddisflies, midges, bryozoans, sponges and other invertebrates. The flora includes black spruce, tree birch, boreal shrubs and wetland and aquatic taxa, which shows that mires, lakes and ponds were present in the area. We describe a new extinct waterwort species Elatine odgaardii. The fossils were deposited in a boreal environment with a mean July air temperature that was at least 9 °C higher than at present. The fossil assemblages show strong similarities with others from Greenland that have been assigned an Early Pleistocene age, and we suggest a similar age for the sediments found at the margin of the Pingorsuit Glacier.
At the Pingorsuit Glacier in North-West Greenland, an organic-rich deposit was discovered at an elevation of 480 m above sea level. The sediments contained remains of vascular plants, mosses, beetles, caddisflies, midges, bryozoans, sponges and other invertebrates. The fossils were deposited in a boreal environment with a mean July air temperature that was at least 9 °C higher than at present.
Presser from the University of Wyoming — Researchers discover ice is sliding toward edges off Greenland Ice Sheet
Ice on the Greenland Ice Sheet doesn't just melt. The ice actually slides rapidly across its bed toward the ice sheet's edges. As a result, because ice motion is from sliding as opposed to ice deformation, ice is being moved to the high-melt marginal zones more rapidly than previously thought.
"That's the kicker. The Greenland Ice Sheet is happily sliding over a surface that theory says it shouldn't be able to rapidly slide over," Humphrey says. "What's important is that, because of this, you get a lot of ice to the oceans or low altitudes where it can melt really fast. It's like a lump of molasses sliding off the continent. It just doesn't melt. It slides toward the ocean."
"Our measurements of sliding-dominated flow over a hard bed in a slow-moving region were quite surprising because people don't typically associate these regions with high sliding," Maier adds. "Generally, people associate lots of sliding motion with regions that have soft beds (mud) or exceptionally high-sliding velocities, such as ice streams. Yet, in this relatively boring region, we found the highest fraction of sliding measured to date.
Thanks for your patience as I try to recover from the news.