GeologyRocksThin crust = melting ice
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I've got a couple of
Thu, 02/07/2008 - 20:27I've got a couple of guesses.
- Thinner crust = higher heatflow & therefore basal melting leading to thinning ice.
- Warm based glaciers are much more erosive than cold based ones and form in warmer conditions. If a warm based area persists for a long time, there would be more crustal lowering through erosion than elsewhere, and being warmer, the area would naturally melt more.
These are just wild guesses though...
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Matt, your first suggestion
Thu, 02/07/2008 - 21:44Matt, your first suggestion is the basis of his idea. The second could be true but I would hope he understands that process and takes it into account. I misquoted in my first post, I said the article says the crust is up to 20% thinner at those spots of melting, but it actually says that geothermal heat was 20% greater under those spots.
Jon, he lists airborne radar and gravity measurements as his method of determining crustal thickness. He also says that the thickness varies across the island, sometimes greatly. I'm not sure how accurate airborne radar is, but I'm sure gravity measurements are affected by what's actually down there. I assume that he takes this into account somehow.
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KU40 wrote: A scientist
Thu, 03/20/2008 - 04:53A scientist from my university did/is doing a study on glacial melting, I believe in Greenland right now. He said that he found that the crust under the melting glaciers was significantly thinner (up to 20%) than under other glaciers in the area which weren't melting at all or as fast, causing higher melting rates and ice streams from the increased heat transfer from underground. He wants to extend his study down to Antarctica, where he says there are many ice streams that aren't caused by global warming.
However he doesn't give a reason as to why the crust may be thinner in these areas or how long they have been so. I was just curious as to how common crustal thinning could be? Could these areas just be the beginning of an igneous intrusion? I figure the only way that crustal thinning across the globe as a whole could be taking place was if either the continents were thinning and flattening out or if somehow the core was heating up which may extend the mantle-crust boundary because of the increased heat effects radiating outwards. The second thought doesn't seem plausible, since from what I've learned our core has only the heat and fuel from when earth formed so heat production could only decrease, not increase.
Or the other option is just that these areas have always had the same crustal thickness throughout the life of the glacier as they do now but the glacier formed over them anyways. But now that the earth's atmosphere is heating it has moved it just past the tipping point for these areas to melt first because of the increased heat from below.
This article really doesn't go into a lot of detail, as I'm sure it's just a preliminary sort of report. What are your thoughts?
Really interesting, thanks for posting this, my best, Dan Howitt.
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Thin crust = melting ice
Submitted by KU40 on Thu, 02/07/2008 - 19:59.A scientist from my university did/is doing a study on glacial melting, I believe in Greenland right now. He said that he found that the crust under the melting glaciers was significantly thinner (up to 20%) than under other glaciers in the area which weren't melting at all or as fast, causing higher melting rates and ice streams from the increased heat transfer from underground. He wants to extend his study down to Antarctica, where he says there are many ice streams that aren't caused by global warming.
However he doesn't give a reason as to why the crust may be thinner in these areas or how long they have been so. I was just curious as to how common crustal thinning could be? Could these areas just be the beginning of an igneous intrusion? I figure the only way that crustal thinning across the globe as a whole could be taking place was if either the continents were thinning and flattening out or if somehow the core was heating up which may extend the mantle-crust boundary because of the increased heat effects radiating outwards. The second thought doesn't seem plausible, since from what I've learned our core has only the heat and fuel from when earth formed so heat production could only decrease, not increase.
Or the other option is just that these areas have always had the same crustal thickness throughout the life of the glacier as they do now but the glacier formed over them anyways. But now that the earth's atmosphere is heating it has moved it just past the tipping point for these areas to melt first because of the increased heat from below.
This article really doesn't go into a lot of detail, as I'm sure it's just a preliminary sort of report. What are your thoughts?