More Bad News on Ice Melt: This Time Greenland

May 19, 2014

greenland_meltvalleys2014rignot-2

Illustration showing newly revealed topography of subsealevel glacial channels in Greenland, from the new Nature Geoscience paper by Morlighem, Rignot et al Note below sea level “bowl” in the interior.

Eric Rignot and his team strike again. This time Greenland.  More vulnerable to melt, more sea level rise likely.  Yadda Yadda.

Nature Geoscience:

The bed topography beneath the Greenland ice sheet controls the flow of ice and its discharge into the ocean. Outlet glaciers move through a set of narrow valleys whose detailed geometry is poorly known, especially along the southern coasts. As a result, the contribution of the Greenland ice sheet and its glaciers to sea-level change in the coming century is uncertain. Here, we combine sparse ice-thickness data derived from airborne radar soundings with satellite- derived high-resolution ice motion data through a mass conservation optimization scheme . We infer ice thickness and bed topography along the entire periphery of the Greenland ice sheet at an unprecedented level of spatial detail and precision. We detect widespread ice-covered valleys that extend significantly deeper below sea level and farther inland than previously thought. Our findings imply that the outlet glaciers of Greenland, and the ice sheet as a whole, are probably more vulnerable to ocean thermal forcing and peripheral thinning than inferred previously from existing numerical ice-sheet models. 

Basic issue – Greenland is essentially a ring of mountains surrounding a bowl of ice.  Where fingers of the sea can reach in beneath the ice and get to the soft underbelly, glacial outflow can proceed really quickly. New paper indicates there’s a lot more fingers than we thought, and longer.
This possibility was discussed in my video last year by the ever-prescient Dr.Mike MacCracken.

Phys.Org:

Greenland’s icy reaches are far more vulnerable to warm ocean waters from climate change than had been thought, according to new research by UC Irvine and NASA glaciologists. The work, published today in Nature Geoscience, shows previously uncharted deep valleys stretching for dozens of miles under the Greenland Ice Sheet.

The bedrock canyons sit well below sea level, meaning that as subtropical Atlantic waters hit the fronts of hundreds of glaciers, those edges will erode much further than had been assumed and release far greater amounts of water.

Ice melt from the subcontinent has already accelerated as warmer marine currents have migrated north, but older models predicted that once higher ground was reached in a few years, the ocean-induced melting would halt. Greenland’s frozen mass would stop shrinking, and its effect on higher sea waters would be curtailed.

“That turns out to be incorrect. The glaciers of Greenland are likely to retreat faster and farther inland than anticipated – and for much longer – according to this very different topography we’ve discovered beneath the ice,” said lead author Mathieu Morlighem, a UCI associate project scientist. “This has major implications, because the glacier melt will contribute much more to rising seas around the globe.”

To obtain the results, Morlighem developed a breakthrough method that for the first time offers a comprehensive view of Greenland’s entire periphery. It’s nearly impossible to accurately survey at ground level the subcontinent’s rugged, rocky subsurface, which descends as much as 3 miles beneath the thick ice cap.

Greenland will be far greater contributor to sea rise than expected



Since the 1970s, limited ice thickness data has been collected via radar pinging of the boundary between the ice and the bedrock. Along the coastline, though, rough surface ice and pockets of water cluttered the radar sounding, so large swaths of the bed remained invisible.

Measurements of Greenland’s topography have tripled since 2009, thanks to NASA Operation IceBridge flights. But Morlighem quickly realized that while that data provided a fuller picture than had the earlier radar readings, there were still major gaps between the flight lines.

To reveal the full subterranean landscape, he designed a novel “mass conservation algorithm” that combined the previous ice thickness measurements with information on the velocity and direction of its movement and estimates of snowfall and surface melt.

The difference was spectacular. What appeared to be shallow glaciers at the very edges of Greenland are actually long, deep fingers stretching more than 100 kilometers (almost 65 miles) inland.

“We anticipate that these results will have a profound and transforming impact on computer models of  evolution in Greenland in a warming climate,” the researchers conclude.

“Operation IceBridge vastly improved our knowledge of bed topography beneath the Greenland Ice Sheet,” said co-author Eric Rignot of UC Irvine and NASA’s Jet Propulsion Laboratory. “This new study takes a quantum leap at filling the remaining, critical data gaps on the map.”

The team also reported stark new findings last week on accelerated glacial melt in West Antarctica. Together, the papers “suggest that the globe’s  sheets will contribute far more to  rise than current projections show,” Rignot said.

 

 

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12 Responses to “More Bad News on Ice Melt: This Time Greenland”

  1. redskylite Says:

    More on the latest satellite observations on the Antarctic from the B.B.C, difficult to digest, but a tipping point of ice melt has occurred. Never in my wildest dreams could I have ever imagined such events happening. We really do need realists in world governments now, and I rest my hopes on the U.N and next generation.

    http://www.bbc.com/news/science-environment-27465050

  2. rayduray Says:

    The Guardian takes a close look at Holland’s new strategy of making “Room For The River”, a scheme to allow for climate change’s impact of greater rainfall/flooding events to be absorbed and tamed by recreating floodplains. Sea level rise is also addressed.

    http://www.theguardian.com/environment/2014/may/19/floods-dutch-britain-netherlands-climatechange?commentpage=1

    I enjoyed the comparison between the no-fuss way the Dutch approach this issue versus the dance-of-the-penny-pinching-nincompoops approach in the UK.

  3. redskylite Says:

    An 11-year-old wants to know how hard you think it would be for humanity to decarbonize our energy system in time to prevent climate from changing too much.

    In 1763 James Watt designed a revolutionary new steam engine that was powered by coal, the industrial revolution was born as more and more countries embraced the new technologies in a transition to new manufacturing processes. It was a turning point in human history, masses of ordinary people began to enjoy sustained growth. In 1896 Svante Arrhenius developed a formulae to calculate the temperature rise from the greenhouse effect caused by industrial gases like Carbon Dioxide. Not foreseeing mankind’s rapid industrial growth he calculated that Earth’s COշ atmospheric concentration would double in 3000 years, causing a 5°C rise in average temperature.. His formulae is still used today, but we now expect the doubling to occur by the year 2100, if we carry on our current practises in industry. Observations taken recently in the Antarctic indicate that a terrible tipping point has been passed, ice melt is accelerating, and sea levels will rise over 1 meter by 2100, and continue rising by at least 5 meters during the following century. This will devastate countries like Bangladesh and many of our major cities, like New York and Miami. Clearly we must change our ways and deal with these man made problems. We can make energy efficiency changes, such as using LED lighting, more efficient car engines with a higher fuel consumption, stop tilling our farms to enable more carbon retention in the soils, architectural changes in buildings, such as a higher degree of insulation. We have several non carbon energy producing technologies today that we can use to replace coal as a generator of electricity, they include, nuclear, solar, wind, tide and marine, hydroelectric and geothermal, and one or more of these technologies can be selected by most of our countries in place of continued fossil fuel usage, and we can meet all of our energy needs with non fossil fuel use by as early as 2030-2050. To maintain our current life style we need to up-scale and develop new ideas by the end of the century.For example high altitude winds are one of the largest untapped renewable resources in the world. Professor Ken Caldeira of the Carnegie Institute for Science at Stanford University published research on the sector and concluded; “There is enough energy in high altitude winds to power civilization 100 times over.” in a pilot scheme that is proven to produce double the energy of similarly sized tower-mounted turbines, a system, called Buoyant Air Turbine (or BAT), is now readying for commercial deployment in rural Alaska.

  4. ubrew12 Says:

    So, basically, Fjords are found in Greenland as they are in Norway. Not to take away from this excellent research, but was this anticipated, even a little bit? My hindsight is 20-20, but it seems possible that it would have been.

  5. adelady Says:

    I’d say it was anticipated, but scientists won’t say anything-at-all unless they have measurements and observations to back such thoughts up. They wouldn’t have done this research unless they needed to know the details. I know I’ve vaguely wondered about avenues for warmer water getting under the Greenland ice sheet at a couple of “hard” science sites a while ago and got myself soundly boxed around the ears for such groundless speculation. I didn’t even know – and wasn’t told about – this research being on foot at the time.

    btw. I seem to be first cab off the rank, so I’m claiming ray duray’s “dance-of-the-penny-pinching-nincompoops” for myself.

  6. rayduray Says:

    Re: “btw. I seem to be first cab off the rank, so I’m claiming ray duray’s “dance-of-the-penny-pinching-nincompoops” for myself.”

    Claim all ye want fair lady. I seen to have forgotten to copyright that bit of folderol.

    You’re vexing story about getting shushed online regarding the Greenland fiord concept has me wondering if the boys thought “groundless speculation” was just too good a pun to not want to pun-ish you? Or, as I’m prone to say from time to time, considering your sensible conjecture, sometimes you go for results and instead you get consequences. This happened to me today on the Jeff Masters’ blog at Weather Underground. Some damn little twerp came on the thread asking all sorts of climate related questions, saying that he was a skeptic. I took the time to answer. a fair number of his questions, with citations. Then he dissed me and said he preferred to remain a skeptic without having addressed a single one of dozens of topics I touched on, and told me to bugger off with all my damn hyperlinks! Sometimes you just don’t get any respect. That’ll teach me to engage with someone who leads in with “HAARP and chemtrails are leading causes of climate change…. ” 🙂


  7. TWO basic faults in the linear reasoning

    Where fingers of the sea can reach in beneath the ice and get to the soft underbelly, glacial outflow can proceed really quickly…..NO BECAUSE IS SOME ISOSTATIC COMPENSATION
    AND STRESS RELATED FAULTS THAT GOING ON AND OFF

    New paper indicates there’s a lot more fingers than we thought, and longer.
    This possibility was discussed in my video last year by the ever-prescient Dr.Mike MacCracken.

    Greenland’s icy reaches are far more vulnerable to warm ocean waters from climate change than had been thought, according to new research by UC Irvine and NASA glaciologists. The work, published today in Nature Geoscience, shows previously uncharted deep valleys stretching for dozens of miles under the Greenland Ice Sheet.
    The bedrock canyons sit well below sea level, meaning that as subtropical Atlantic waters hit the fronts of hundreds of glaciers,THEY GOING TO GO FROM WARM SUBTROPICAL TO 4ºC
    AND SINK….AND WATER COLD AND WITH LOW DENSITY GOING TO APPEAR IN GREAT AMOUNTS AT THE SURFACE… those edges will not erode much further and if they do the New Yorkers going to freeze in one super or hyper winter


  8. […] Jakobshavn glacier recently made headlines for its record-breakingly fast flow. Now, a new satellite image provides a visual of this […]


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  10. […] Sports Analysis for Ohio State FansThe Buckeye Blog – College Sports Analysis for Ohio State FansMore Bad News on Ice Melt: This Time GreenlandWhy Greenland’s Melting Could Be the Biggest Climate Disaster of AllThe Buckeye Blog – College […]


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