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ambience: Glacier Melt
In Antarctica, sheets of ice get up to two and half miles thick. Beneath this ice there exists a geographic feature that is unique in all the world. I’m Jim Metzner and this is the Pulse of the Planet.
“Well, a sub-glacial lake exists beneath thick ice sheets.”
John Priscu is with the Department of Land Resources and Environmental Sciences at Montana State University at Bozeman. I asked him how sub-glacial lakes are formed.
“There are about 100 sub-glacial lakes identified in Antarctica. It’s believed they exist there primarily because the thickness of the ice increases the pressure under the two and a half mile thick ice sheet to the point where you can actually reduce the freezing point a little bit, and that really gives a very nice situation for liquid water to form. So, right now, it is thought that most of the sub-glacial lakes do exist beneath the Antarctic ice sheet. These are really the only lakes of their kind in the world, and the Antarctic ice sheet has been in existence for about 20 million years, so some of these lakes have been isolated from the atmosphere for 20 million years.”
And what was Earth like 20 million years ago?
“Well, 20 million years ago the Antarctic continent was just becoming a glaciated continent. Prior to 20 million years ago there were plants, trees, animals running around the continent, and then Antarctic became isolated because of ocean currents, and we got this onset of glaciation. And the whole ice sheet started growing from the high mountains and extended all the way down to the ocean. So, 20 million years ago the Earth went from a transition of relatively clement, warm climate to a frozen state.”
We’ll hear more about Antarctica’s sub-glacial lakes in future programs. Pulse of the Planet is made possible by the National Science Foundation.
I’m Jim Metzner.
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