New study in Nature Climate Change on melt in Greenland.
Compare to our Dark Snow video from this past summer, above.
Existing computer models may be severely underestimating the risk to Greenland’s ice sheet — which would add 20 feet to sea levels if it all melted — from warming temperatures, according to two studies released Monday.
Satellite data were instrumental for both studies — one which concludes that Greenland is likely to see many more lakes that speed up melt, and the other which better tracks large glaciers all around Earth’s largest island.
The lakes study, published in the peer-reviewed Nature Climate Change, found that what are called “supraglacial lakes” have been migrating inland since the 1970s as temperatures warm, and could double on Greenland by 2060.
The study upends models used by the Intergovernmental Panel on Climate Change because they “didn’t allow for lake spreading, so the work has to be done again,” study co-author Andrew Shepherd, director of Britain’s Centre for Polar Observation and Modelling, told NBCNews.com.
Those lakes can speed up ice loss since, being darker than the white ice, they can absorb more of the sun’s heat and cause melting. The melt itself creates channels through the ice sheet to weaken it further, sending ice off the sheet and into the ocean.
“When you pour pancake batter into a pan, if it rushes quickly to the edges of the pan, you end up with a thin pancake,” study lead author Amber Leeson, a researcher at Britain’s University of Leeds, explained in a statement. “It’s similar to what happens with ice sheets: The faster it flows, the thinner it will be.
“When the ice sheet is thinner,” she added, “it is at a slightly lower elevation and at the mercy of warmer air temperatures than it would have been if it were thicker, increasing the size of the melt zone around the edge of the ice sheet.”
From the paper:
Our study demonstrates that (supra glacial lakes) large enough to drain will in fact spread far into the ice-sheet interior as climate warms, which suggests that projections of the ice-sheet dynamical imbalance should be revised to account for the expected evolution in their distribution. Establishing the degree to which the inland spread of SGLs will affect future ice-sheet motion is now a matter of considerable concern.
David Appell in Yale Climate Connections:
SAN FRANCISCO, CA, DECEMBER 15, 2014 — If Arctic sea ice is the canary in the coal mines that are causing global warming, Greenland is the 800-pound gorilla that sits in the corner, quiet and ponderous, but packing a heavy wallop and ready to use it.
Scientists at the American Geophysical Union’s Fall Meeting here have been watching the gorilla carefully, and are learning things — surprising and troubling new things — about the stirring of this big beast of ice. Among them are the discovery of aquifers and buried lakes of water that are liquid year-round, unexpected dense layers of ice high on the sheet that may contribute to flooding, and that Greenland had rapid melting from 1900 to 1930 as the Earth came out of the Little Ice Age — more rapid even than today’s melting.
“New tools are allowing us to see these subsurface processes for the first time,” said Mike MacFerrin, a researcher at the University of Colorado at Boulder’s CIRES research institute. Ground-penetrating radar pulled behind snowmobiles and systematic flyovers from NASA’s Operation Icebridge have led to vast quantities of new data that have brought quick discoveries and insights over just the last few years.
Accelerated Melting
The island of Greenland holds almost 3 million billion metric tons of ice, enough to raise sea level over twenty feet if it all warms away. It’s now losing almost 400 billion tons of ice a year, and the loss rate is accelerating, up almost 150 percent since the first half of last decade. MacFerrin said, “In the next century, Greenland melt may raise global sea level by one to three feet.”
Surprisingly, the nature of the melt has changed in recent years. When once it was mostly streaming glaciers discharging calves into the sea, surface melting and runoff surpassed discharge around 2007. This runoff, rather than ice dynamics, is expected to dominate Greenland’s ice sheet’s contribution to sea level rise this century.
Dunboldguy and John,
I can’t blame this one on Dragon, as it was entirely my fault. But here’s the correct article and address, 95% of Climate Models Agree: The Observations Must be Wrong, http://tinyurl.com/mc3ggqd . This article has a graph with the models along with the real readings of climate, showing that how poorly the models have done in estimating the future weather and climate.Please address this apparent improvement in the models, how they underrepresented the true rate of warming. Looks to me like they are grossly overrepresenting it, by many factors.
I can’t actually read the entire sentences you’ve listed but I will address general sea-level rise in general and also comment on glaciers apparent receding. Here are a few links to articles on sea-ice: http://bit.ly/1JAagFF ,http://bit.ly/1IFNsjN, http://bit.ly/1hvUBgO , and http://bit.ly/1JAaj4k . Finally, here’s new research that suggests that in the time of the Roman Empire, they (glaciers) were smaller than today. And 7,000 years ago they probably weren’t around at all, http://bit.ly/1i07T5W. It appears that sea-ice and glaciers have natural cycles where they recede, and then grow.
Here’s fletch, again dusting off the cobwebs on old threads. Can’t really see what he’s “addressing” or “commenting on” here, but “It appears that sea-ice and glaciers have natural cycles where they recede, and then grow” may be one of his best yet .
“…sea-ice and glaciers have natural cycles where they recede, and then grow”
Yes fletch, that’s certainly true, and the only reply it requires is DUH! and DOUBLE DUH!