Greenland Ice, and How it Melts

April 3, 2014

Rumors swirling around a new Dark Snow Project expedition this summer. More on this soon, I hope.

Meanwhile, good summary of Greenland Ice movement from University of Calgary post doc Kevin Whitehead.

Dr. Whitehead does a nice job of pointing out the various forces at work – note especially the attention given at the end to surface melt as the emerging major wild card in mass loss. It is this surface melt that is most affected by decreased whiteness, or albedo of the surface, as darkening agents from dust, to industrial smoke, to wildfire soot, increase on the glacier surface.
A new subject of investigation is the affects of biological communities on the ice, algae and like organisms that we may be helping to multiply by fertilization and continued greenhouse warming.

Kevin Whitehead at PlanetSave:

First of all, Greenland is big. At over two million square kilometers, it is roughly ten times the size of the United Kingdom. Approximately 82% of its surface is covered by the ice sheet, which has a volume of 2.38 million km3 and reaches a depth of 3,000 meters in places. However, to put its size into perspective, this volume is equivalent to only about 8% of the Antarctic Ice Sheet.

Greenland differs from Antarctica in another very important aspect. Antarctica has a number of mountain ranges buried underneath the ice. However in Greenland the mountainous areas are generally located at the coast and tend to ring the island. The center of Greenland is in effect a large bowl, occupied by the ice sheet. This topography means that ice from the interior can only drain to the ocean through a few large outlet glaciers, which occur wherever there are gaps in the coastal mountains. These glaciers are like major rivers, draining vast regions of the ice sheet.

(see video above for more description of this)

The Role of Outlet Glaciers

The largest outlet glacier in Greenland is Jakobshavn Isbræ, which drains an area of approximately 110,000 km2,or some 6% of the entire ice sheet. Like most of the major outlet glaciers for the Greenland Ice Sheet Jakobshavn Isbræ flows into a deepwater fiord. This massive glacier produces an estimated 35 billion metric tons of icebergs per year, around 10% of the Greenland total, and is believed to have been the source of the iceberg which sunk the Titanic.

The role of the outlet glaciers is therefore fundamental to any understanding of what is happening to the Greenland Ice Sheet. Prior to 2005, measurements suggested that approximately 58% of ice loss from the ice sheet occurred through ice discharge, rather than surface melt. Scientists also noted that the major outlet glaciers have been increasing in speed in recent years. For example, a recent study found that the maximum speed of Jakobshavn Isbræ, a few kilometres upstream from its terminus, had increased to around 17 km per year by the summer of 2013. This makes  it one of the fastest-moving glaciers on Earth, and represents a fourfold increase in speed since the mid 1990s. This speed increase has been accompanied by thinning of the lower glacier and a by a retreat of the glacier terminus, which has moved back several kilometers in recent years. This occurs as icebergs break free of the terminus in a process known as calving. One of the largest calving events ever recorded was captured in this video.

It is likely that the local topography of the seabed has played an important part in the speed up of Jakobshavn Isbræ. Nonetheless similar speed increases have been observed for most of Greenland’s outlet glaciers. Scientists believe that the key to such speed increases may lie with the position of the grounding line, which is the point at which a glacier flowing into the ocean separates from its bed and begins to float. Beyond this point, there is no resistance to glacier flow so speeds increase rapidly.

Since most Greenland outlet glaciers terminate in deepwater fiords and are hundreds of meters thick, the base of the glacier comes directly into contact with water from the ocean depths. A number of recent studies have suggested that changes to ocean circulation patterns may be causing increased stratification of ocean waters at higher latitudes. The effect of this trend is that a layer of denser, saltier water is now entering the fiords in which outlet glaciers terminate and causing the glaciers to melt from beneath. This dense ocean water is trapped beneath a layer of meltwater from the glacier, which is less saline and has a comparatively low density. Increased melting at the glacier base causes the grounding line to retreat, lowering resistance to glacier flow, and thus causing the glacier to accelerate. Thus it appears likely that increased ice discharge from Greenland may be a direct consequence of ocean warming at mid and high latitudes, a process which illustrates a complex interaction between different elements of the Earth system.

Eventually it is likely that most outlet glaciers will retreat to the point that they terminate in shallow water, or on land. When they reach this point then it is likely that flow rates will drop dramatically, and a new equilibrium will be established. However it is estimated that it will take several decades for most of the major outlet glaciers to reach this stage. As long as they terminate in deep water, accelerated flow rates are likely to continue, and possibly even to increase, contributing significantly to sea level rise in the process.

Surface Melting

Another mechanism which is believed to have contributed to increased flow rates of the main outlet glaciers is increased surface melting. During the summer, meltwater tends to collect in ponds on the surface of the ice. Weaknesses within the ice can often result in catastrophic drainage of these ponds. Elsewhere, rivers of meltwater flow across the ice sheet, before disappearing into the depths of the ice, through what are known as “moulins”. Much of this meltwater will eventually end up at the base of the ice sheet, where it provides a lubricating layer between the ice and the underlying ground, lessening resistance to glacial flow. While this effect is believed to be small compared with the effect of grounding-line retreat, it is nonetheless believed to be a contributor to the speed up of the outlet glaciers.

However, perhaps the most worrying conclusion from recent studies is that although ice discharge has increased considerably since the mid 1990s, it now only comprises a third of the total mass loss from the ice sheet; a near complete reversal from the situation prior to 2005, when ice discharge was the dominant process. Since 2009, some 84% of the increased mass loss has occurred through surface melting, marking a dramatic increase in the amount of melting now occurring. This trend was underscored over a four-day period in July 2012, when satellite measurements revealed that surface melting occurred over some 97% of the Greenland Ice Sheet. Such widespread melting has never been observed before in over 30 years of satellite observations, with positive temperatures even being reported at Summit Station, the highest point of the ice sheet.

So clearly the Greenland Ice Sheet is losing mass much more rapidly than in the past, but is it in danger of collapsing? Recent studies suggest that if current rates of ice discharge continue, this alone is likely to raise global sea levels by around 3 cm by the end of the century. In a worst-case scenario, if the rate of ice discharge were to increase dramatically, it could cause sea levels to rise by as much as 8 cm over this time period. The big unknown is how much surface melting could occur over the same time. If rates remain similar to those of today, then sea level rise from Greenland alone is likely to be between 10 cm and 25 cm by the end of the century. However if surface melt rates increase, then this figure could be significantly higher.

As readers know, albedo, or lightness of the ice sheet is decreasing in Greenland. Key drivers are poorly understood – and yet another powerful one may be emerging..

Shooting as Dr. Marek Stibal, Dark Snow’s resident microbiologist, takes samples of cryoconite near the Illulisat calving front.

ISME Journal (International  Society for Microbiology Ecology):

Darkening of parts of the Greenland ice sheet surface during the summer months leads to reduced albedo and increased melting. Here we show that heavily pigmented, actively photosynthesising microalgae and cyanobacteria are present on the bare ice. We demonstrate the widespread abundance of green algae in the Zygnematophyceae on the ice sheet surface in Southwest Greenland. Photophysiological measurements (variable chlorophyll fluorescence) indicate that the ice algae likely use screening mechanisms to downregulate photosynthesis when exposed to high intensities of visible and ultraviolet radiation, rather than non-photochemical quenching or cell movement. Using imaging microspectrophotometry, we demonstrate that intact cells and filaments absorb light with characteristic spectral profiles across ultraviolet and visible wavelengths, whereas inorganic dust particles typical for these areas display little absorption. Our results indicate that the phototrophic community growing directly on the bare ice, through their photophysiology, most likely have an important role in changing albedo, and subsequently may impact melt rates on the ice sheet.

The ISME Journal (2012) 6, 2302–2313; doi:10.1038/ismej.2012.107; published online 27 September 2012


Figure 1 Aerial views of surface ice inland from the Leverett Glacier terminus in West Greenland: (a) algal blooms at station T7, 34 km inland, 5 August 2010; (b) purple brown hue of algal bloom on surface ice at station T7; (c) surface clumping of ice algae; (d) true colour NASA MODIS Terra image acquired 17 August 2010 showing the presence of a dark band and location of sampling stations. Distances from the deglaciated Leverett terminus along the transect were T5 1⁄4 7 km, T6 1⁄4 17 km, T7 1⁄4 34 km, T8 1⁄4 51 km and T9 1⁄4 79 km, S1 was 2 km from the ice margin at Point 660.

Here, Dark Snow project’s resident microbiologist, a co-author of the study mentioned here, describes his research and what he hopes to find in sampling on the ice sheet – something that we’ll hope to document this summer.


Figure 2: Autotrophs from the surface of the Greenland Ice Sheet at station S1: (a) filament of orange-sheathed cyanobacterium; (b) cells of Cylindrocystis brebissonii, stained with Lugol’s iodine resulting in detachment of the protoplast from the cell wall (c) live cell of Mesotaenium cf. berggrenii. (d) live filament of Ancylonema nordenskio ̈dii. Scale bar 1⁄4 10 mm.

18 Responses to “Greenland Ice, and How it Melts”

    • dumboldguy Says:

      Ditto—-a great summary of things posted before as well as a look into the future. We are in for a helluva ride in the Arctic over the next couple of years.

  1. If ice darkening accelerates melting, it follows that ice lightening will decrease melting.

    It may be possible to engineer this.  There are commercially available reflective films which reflect more than 99% of incident sunlight.  If the surface of a glacier, or the bulk of the ice of Greenland, was covered in such film during daylight, the amount of heat absorbed would plummet.  Surface temperatures would exceed freezing much more rarely.

    Any engineered solution would need to cope with cleaning dust off the film, removing and re-laying the film atop new snow, and migrating the reflectors upstream as the ice flows outward.  Perhaps advances in robotics could manage this.  If it was sufficiently successful, it might allow the accumulation of glacial ice beyond historic levels and help address sea-level rise from other causes.

    Erosion of floating ice tongues by seawater may also be amenable to engineered solutions.  Artificial terminal moraines could block the flow of high-density water, decreasing the salinity and density while increasing the freezing point of the water beneath the ice.  This would tend to move the ice grounding point outward again.  This would have to be preceded by measures to cut melting from the top, because floods of meltwater from below the glacier would erode the moraines.

    • Gingerbaker Says:

      This sounds like a job for………………………..


      ^*^*^*^* Super Christo!!!!!!! *^*^*^*^

    • dumboldguy Says:

      An excellent comment, even if it’s a couple of days late for April Fool’s Day. Perhaps E-Pot has finally begged or borrowed a sense of humor? But wait! Could E-Pot be serious? Perhaps so, since he is an “engineer”, and knows how to fix things.

      (Small engineer joke here: How does an engineer prove that a flat tire is really flat? He installs the flat tire on all four corners of the car and measures the height of the car off the ground. If all the measurements of the car’s height at the “low” corner of the car agree within +/- 1/16″, the tire is indeed flat and needs to be repaired.)

      He warms us up here with talk of reflective coverings and the need to clean the dust off them and roll them back so that “new snow” can accumulate, gets us chuckling with his vision of armies of Wallies and R2D2’s dragging the reflective carpet “upstream” as needed, and finally has us rolling in the aisles with the concept of “artificial terminal moraines”. LOL, E-Pot.

      If I am still around when the AGW SHTF and you and all the other “engineers” are suggesting ways to “adapt and mitigate”, I will be waiting eagerly to hear more of your jokes.

      • Interesting attitude.  Do you have any ways of your own to save the Greenland ice sheet, or do you only want to direct snide remarks toward anyone who proposes doing anything other than watching it happen?

        Sort of like any mention of following Sweden’s lead on de-carbonizing electric grids.  Snide remarks, down-votes.  Sit and watch the world burn.

        • dumboldguy Says:

          It may be “interesting” to you, but it’s not an “attitude”. It’s more a reflection of understandings gained and opinions formed and reformed over the past 60 years of life and study. Aside from agreeing with you and Hansen that we needed to ramp up nuclear yesterday and that we need to stop burning coal tomorrow, I have no real “plans” for saving the Greenland ice sheet, other than hoping that mankind wakes up before it’s too late and starts doing the many things that need to be done.

          I know that you care and devote much thought to the problem. That will not, however, get you any slack when you go off as far as you did here. You flatter yourself when you consider what you proposed to be any more helpful than “standing and watching it happen”.

          I admire the hell our of the Swedes for many reasons. We should be so lucky as to ever get our country to run as well as theirs does (same for Norway and Denmark). But Sweden is about the size of California, has maybe 10 million people, and is perhaps a better example of what we might aspire to than a model of what might work in the U.S.

          PS, I like to flatter myself by thinking my comments are perhaps more snarky than snide—-a small but significant difference.

    • Covering an 836,000 square mile area seems rather impossible, not to mention there are Animals living there. What about them?

  2. MorinMoss Says:

    Peter, see below for a NASA video animation on the changing of the Greenland ice sheet that was posted on the SpaceRip YouTube channel

  3. cyhalothrin Says:

    Much of the time on the same side as Engineer-Poet (especially when it comes to nuclear), but I don’t think the project (if it exists) to save Greenland’s ice cap by spreading white film over the surface has any practical chance to work at all.

    Geo-engineering solutions are not even half-baked at best. Either we burn less fossil fuel, or we cook. As for the best way to prevent burning fossil fuel (ie wind, solar, nuclear, a bird flu pandemic, etc) there is considerable room for debate.

    • I don’t think the project (if it exists) to save Greenland’s ice cap by spreading white film over the surface has any practical chance to work at all.

      No such project exists AFAIK.  If any such project is ever undertaken, it will not be out of practicality, but out of necessity.

      Either we burn less fossil fuel, or we cook.

      It’s worse than that:  even if human CO2 emissions stopped tomorrow, the earth would continue to warm due to thermal lag.  That’s the “baked in” warming.

      Geo-engineering solutions are not even half-baked at best.

      Define “half-baked” in this context.  The only way to halt the effects from the baked-in warming would be to yank GHG levels down steeply, which is also geo-engineering.  If efficient reflectors can lower the temperature on Greenland’s ice cap and hold the bulk of it below freezing, some of the effects of warming can be ameliorated while everything else has a chance to stabilize.  Keeping the seas from inundating the world’s coasts is probably cheaper than rebuilding everything ten meters uphill.

      Reflectors on glaciers would probably not be simple films, but part of some kind of robot.  A robot with piezoelectric or shape-memory “muscles”, solar power, and a 99%-reflective skin on one side might be able to spread out like a lily pad, roll itself up and wriggle like a worm, or a host of other behaviors to carry out its function.  Such robots might even gauge their own efficiency and crawl to a recycling station when they were due for replacement, perhaps with one or more totally disabled units or other detritus in tow.

      Such measures would have applications world-wide, not just in Greenland.  Protecting snow in mountains would cool the mountains and hold reservoirs of fresh water into the summer months.  This would help maintain species which rely on that water.  If ice reserves can be expanded, so much the better.

      If half-baked thinking can keep the world to a point of only half-baking, we need more of it.  I get the feeling that a million square miles of reflector film is only a small part of what we’re going to need.

      • rayduray Says:

        Re: “No such project exists AFAIK.”

        Covering glaciers to save them? It’s being attempted on the Rhone Glacier in the Alps:

        • dumboldguy Says:

          A very misleading and basically BS article. It would appear that it is not “researchers” who are covering the ice, but the folks who have drilled a tunnel into it. And the tunnel was drilled so that they could MAKE MONEY by charging admission. And they’re just trying to protect their investment. If any “researchers” use the tunnel, they’re probably being charged admission, and I wonder if anyone has “researched” how much faster the glacier is melting now that warmer air is getting up inside.

    • I agree completely. Instead of focusing our efforts on ‘geo-engineering’, we should be doing the New Deal Project of “Getting The Hell Off Oil Energy!”

      • Oil is less than half of the carbon problem (albeit the most expensive fraction).  GingTHO carbon energy needs to be the goal.

        If we’d had a Manhattan Project push on this starting in 2008, we’d be done already (first controlled chain reaction 2 Dec 1942, Nagasaki bomb 9 August 1945:  2 years, 8 months, 7 days).

        • dumboldguy Says:

          Spoken like a true engineer. Just whip out the slide rules and get enough people to crank the numbers and anything can be “fixed”. I wish it was that easy.

          May I suggest that we have a bit of apples and oranges here? The Manhattan Project was an urgent and tightly focused effort—-WE make a fission bomb and drop it on THEM before they do it to us. Simple—maybe a hundred thousand+ people under the control and direction of a wartime government that was willing to spend the $$$ necessary to get results.

          The “carbon problem” impacts a planet of 7 billion, there is not yet a sense of “wartime” urgency, and there is a large “lobby” working against the idea that there’s even a problem.

          We need to have the SHTF with arctic sea ice, the Greenland ice sheet, accelerating sea level rise, and increasingly crazy weather in order to motivate a Manhattan Project response.

          • Just whip out the slide rules and get enough people to crank the numbers and anything can be “fixed”. I wish it was that easy.

            You fail to understand.  We have previous, successful experience doing most of what we need to do.  All we need to do is re-acquaint ourselves with the historical efforts, duplicate them (which we could easily do in several variants with a budget like Manhattan), and roll out the success stories as we prove them.

            Aren’t the species of the world worth a major production effort?  We could call it “The Arsenal of Climate Defense”.

            The Manhattan Project was an urgent and tightly focused effort—-WE make a fission bomb and drop it on THEM before they do it to us.

            I don’t see how this would be any less simple or focused.  We make carbon-free steam generators and industrial process-heat sources that we can roll out in large volume, and install them as fast as practical.  We have 15 years, not less than 4.  We can do this without having our industrial capacity destroyed by enemy action.  The big problems are not engineering, they’re political.

            The “carbon problem” impacts a planet of 7 billion, there is not yet a sense of “wartime” urgency, and there is a large “lobby” working against the idea that there’s even a problem.

            Indeed.  No argument.

            We need to have the SHTF … in order to motivate a Manhattan Project response.

            And you need to get at least some of the groups like the Greens, the UCS, and the Sierra Club to publicly see the light and change their stance.  Not easy.

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