The Finger Lakes in New York state were formed by glaciers,
which began to retreat as man turned to fire to cook his meals.
Posted on 10/20/2006 1:24:01 PM PDT by cogitator
ping!
12,000 years ago where I am sitting now was under 3 miles of ice!
Now it isn't......
Global warming? Yes. Man made? No.
So Greenland may actually finally be *gasp* green?
I guess this means the Vikings can again settle it.
Wonder what caused it to be habitable back then...
So, ice isn't suppose to melt there in the SUMMERTIME?
"I guess this means the Vikings can again settle it.
Wonder what caused it to be habitable back then..."
I think you have answered your own question. Global Warming.
"unsettling trend, as it currently stands"
Why?
Because if the trend persists, the entire ice sheet could be destabilized, as is indicated by some global warming scenarios for the next century and into the 22nd century.
I read the link, but I don't see a definition of destabilization. The closest thing was rising sea levels would unanchor the ice sheets and cause them to break up. That is far flung as you know, sea levels would need to rise orders of magnitude more than current trends and predictions for that to happen. Another candidate is the breakup and darkening of the ice surface from melting. But that clearly isn't happening except on the fringes. Most of it is whitening, just the opposite. "Destabilization" seems to be qualitative and speculative.
The article points that out. "Destabilization" (my term) refers to what the article describes as increased melting leading to accelerated disintegration; major sea-level rise isn't necessary to initiate large-scale disintegration. Note that the article points out that the process is expected to be non-linear (meaning hard to predict), and that once "large-scale" break up starts it will be virtually impossible to stop.
A lot of ice sheets are prevented from faster flow to the ocean by the ice tongue or outflow area that is anchored to the bottom. If this area becomes disconnected from the bottom, ice sheet flows can accelerate.
The only quantitative study I can find is about ice sheets in Antarctica accelerating when the locking ice shelves broke up. I haven't found anything on polar ice sheets breaking up, only non-polar. With the snow increasing in Greenland and Antarctica, it's hard to imagine a break-up from "disintegration".
Greenland Ice Sheet Losing Mass
I have a Science reference for you; abstract looks interesting:
Surface Melt-Induced Acceleration of Greenland Ice-Sheet Flow
This is the mechanism that Hansen's worried about for ice-sheet collapse/disintegration; lubrication by meltwater of the ice flow zones.
The first article doesn't say much, the second leaves out an important fact: thick glaciers on Greenland don't percolate meltwater and are primarily geothermally heated. Their case might be made for the thin edges, but it's irrelevant for the bulk of the ice sheet.
The article indicates the observations were for a "equilibrium zone" of the Greenland ice sheet. As the ice sheet changes, I would also expect that the location and size of a zone thusly described would also change.
I didn't see "equilibrium zone" in there. It would help if that was defined since it might just be parts near the melting edge. Obviously if nothing but snow buildup is happening to the bulk of the ice sheet, then it doesn't much matter what happens in the "equilibrium zones".
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