From the UNIVERSITY OF EXETER and the “don’t ignore the black soot left at the bottom after the drainage” department.
Greenland’s ice sheet plumbing system revealed
Pioneering new research sheds light on the impact of climate change on subglacial lakes found under the Greenland ice sheet
A team of experts, led by Dr Steven Palmer from the University of Exeter, has studied the water flow paths from one such subglacial lake, which drained beneath the ice sheet in 2011.
The study shows, for the first time, how water drained from the lake – via a subglacial tunnel. Significantly, the authors present satellite observations that show that a similar event happened in 1995, suggesting that this lake fills and drains periodically.
The study, called Subglacial lake drainage detected beneath the Greenland Ice Sheet is published in the journal Nature Communications.
Lead author Dr Steven Palmer, from Geography at the University of Exeter, said:
“Our research reveals details about the plumbing system beneath the Greenland ice sheet, which is important because the configuration of that system has an impact on the flow speed of the overlying ice.”
Although the ice sheet response to draining subglacial lakes has previously been observed in Antarctica, this is the first time that a similar phenomenon has been observed in Greenland.
However, unlike Antarctic subglacial lakes, which are sustained through melting of the ice sheet base, the study shows that this subglacial lake has been fed by surface meltwater flowing down a nearby moulin – a circular, vertical shaft found within a glacier.
The scientists predict that as the Arctic continues to warm, increasing volumes of surface meltwater routed to the ice sheet bed will cause subglacial lake drainage to become more common in the future. Because the way in which water moves beneath ice sheets strongly affects ice flow speeds, this increased drainage frequency could affect the sensitivity of the ice sheet to climate change, impacting the rate of future sea level change.
Dr Palmer added:
“We have made the first observations of how the Greenland ice sheet responds to subglacial lake drainage, but more research is required to understand the long-term impacts of these events. It is possible that draining subglacial lakes act to release the pressure at the ice sheet base, meaning that if they drain more frequently in the future, they may actually result in slower ice sheet flow overall”.
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He must be a moulin rogue.
I’ll get me coat.
Can’t help but note ‘…as the Arctic continues to warm…’ is in there. Is this real warming or just imaginary created by surface temperature series?
Or are these lakes related to geothermic factors?
I have written a new article on how Ice Ages are initiated and regulated by Milankovitch cycles, dust and albedo. With not a trace of CO2 feedbacks in sight. If this is correct then the role of CO2 in both Ice Age climate and modern climate, has been grossly exaggerated.
If anyone would like to read it, please send an email to: ralf dot ellis at me dot com
Ralph
I have written a new article on how Ice Ages are initiated and regulated by Milankovitch cycles, dust and albedo. With not a trace of CO2 feedbacks in sight. If this is correct then the role of CO2 in both Ice Age climate and modern climate, has been grossly exaggerated.
If anyone would like to read it, please send an email to: ralf dot ellis at me dot com
Ralph
Just a personal observation from Ottawa. For years I have noticed that during our intense winters, thaw and freeze and thaw and freeze again, that the last parts of my lane way to complete melt were those covered in black goop that has been deposited from our car after it has been driving on our roads. This has constantly occurred for the last 25 years in which we have lived in this house.
Yes. I know that the road goop has lots of salt that we use to thaw our winter roads, so I have never understood this phenomenon. Maybe it is acting as a blanket against the sun. The areas affected are receiving the same amount of sun as those that are not.
Maybe a point Denise, let’s get a pac together and some funding to investigate. It could be a sunblock, preventing the individual ice crystals from reflect mirroring onto each other.
I don’t see a link to this paper. What is with people who post here and don’t let us have a link so we can check out what the paper itself says?
I want to know what PART of “the” ice sheet they re talking about. Why is the location important? Because there is not ONE Greenland ice sheet. The great majority of Greenland is the interior, in a basin, and is almost entirely held inside by ring of mountains around the periphery of Greenland, a few score miles inland. They hold the interior ice sheet in, and at the same time their outboard slopes are where the glaciers are. Ice sheets and glaciers are not one and the same thing, even though they are both made up of the same ice. Ice on slopes is glaciers, and ice on the flat or contained within basins are ice sheets. Their dynamics are completely different. Those on slopes MOVE downhill, and those on the flat or contained in basins basically just sit there (though some motion occurs). The interior ice sheets of Greenland only have a very few outlets to the sea. The vast, VAST majority of ice in the interior has no chance to either melt (too cold) or move (too flat or held in a basin). It is IMPORTANT to distinguish between glaciers and ice sheets, especially ice sheets contained within basins.
The Mouilns are basically in the interior ice sheet. Such things should not be forming in flowing glaciers. In glaciers there is too much shearing at various levels – meaning that the internal structure is churning and changing all the time. Also, ice at different depths within glaciers does not flow equally. The basal ice- even with water there – will flow slower than ice farther up (vertically up), due to friction with the basal ground surface and its irregularities, which always contains a lot of projections and ridges, large and small. Ice shears internally because it is crystalline and has fault planes, which are weak internal planes (more or less horizontal to the ground surface below) that have lower strength. The ice just above the basal ice moves slower than ice up higher because it is being retarded by the friction and resistance to shearing relative to the basal ice itself, which is going relatively slowly. This means that internally glaciers are weird creatures, with no stable internal structure; it is always changing. Every level slides over the one below it, and the friction breaks both layers up. The surface ice travels fastest and is easiest to see and measure but gives little evidence of what is going on below. The basal ice is the most difficult to get at and measure, so statements about basal ice should ALWAYS be suspect.
All of what is stated in this have to be understood within the three contexts I’ve mentioned here – ice sheets-in-basins vs glaciers; internal ice shear planes; churning/mixing.
The earth itself is a heat source. This heat flows from the inside (where the lava is) to the outside (where the ice is). When this heat reaches the ice, some of the ice melts, lubricating the flow of glaciers and facilitating the development of sub-glacial rivers. This occurs 24/7.
Solar melting of glaciers is both diurnal and seasonal, and the melt water flows downhill, often finding cracks in the ice-pack and percolating down to the bottom, where it joins the rivers facilitated by the geothermal heating.