Of course, surface water can propagate to the bottom in Greenland,
which propagates a heating signal as well as a lubricant. I haven't
heard of anything comparable happening in Antarctica, which gets much
less summer sun than does balmy Greenland.
Liquid water and soft mud at the base of a moving glacier matters a lot.
For the bulk of an ice sheet I suppose it matters much less.
For West Antarctica, there is the question of what sets the maximum
width of a glacier, and the answer appears to be topography. Which
means that parts of the WAIS might disappear relatively quickly by
becoming very wide moving glaciers, which is probably what the 12ka
meltwater pulse was about.
This in turn means that the hydrology under the WAIS matters, which in
turn, if I understand correctly, makes a young fellow down the hall
from me busy on a doctoral thesis.
mt
On 8/22/07, James Annan <[EMAIL PROTECTED]> wrote:
>
> Michael Tobis wrote:
> > No, actually liquid water forms more easily at higher pressure and
> > there is an Antarctic subglacial hydrological system which originates
> > geothermally. Lake Vostok is the famous instance, but it has emerged
> > there are flows among these reservoirs as well deep in the Antarctic
> > interior.
>
> I think that misses the point, which is that there is no obvious way for
> surface water to percolate down through 1km of ice to reach the ice bed.
> For that matter, where there is already water down there, it presumably
> wouldn't matter if more joined it, from the POV of lubrication.
>
> I do wonder how much the discovery of water sloshing around has
> influenced beliefs about the (possibly) isolated Vostok ecosystem. If
> water can move more-or-less freely under large areas of the ice sheet,
> then it seems entirely plausible to me (but I'm guessing really) that it
> is connected to the open ocean. Anyway, that's another matter entirely,
> but not one that I've seen much discussion of. Maybe there are good
> reasons why an ocean connection is implausible.
>
> James
>
> >
>
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