Re: [asa] Subglacial Water System Moving Faster Than Previously Thought

Rich, was this subglacial water system recently formed, or has it been
around for a long time and only been recently discovered? It seems that if
this is a recent phenomenon, it would perhaps be an "uh oh." If it has been
around for a long time and has only been recently discovered, however,
couldn't that suggest that some fears about deglaciation are overstated --
that glaciers are always very dynamic systems that aren't likely to collapse
catastrophically due to some kind of meltwater feedback loop? I'm thinking
of the scenes in An Inconvenient Truth concerning water on top of the
glaciers in Antarctica (if I'm remembering this right).

On 2/15/07, Rich Blinne <rich.blinne@gmail.com> wrote:
>
> From today's Science Express:
>
> http://www.sciencemag.org/cgi/content/abstract/1136897v1
>
> An Active Subglacial Water System in West Antarctica Mapped from Space *Helen
> Amanda Fricker 1*, Ted Scambos 2, Robert Bindschadler 3, Laurie Padman 4 *
>
> 1 Scripps Institution of Oceanography, University of California, San
> Diego, La Jolla, CA 92093, USA.
> 2 National Snow and Ice Data Center, University of Colorado, Boulder, CO
> 80302, USA.
> 3 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
> 4 Earth & Space Research, Corvallis, OR 97333, USA.
>
> * To whom correspondence should be addressed.
> Helen Amanda Fricker , E-mail: hafricker@ucsd.edu
>
> Satellite laser altimeter elevation profiles from 2003-2006 collected over
> the lower parts of Whillans and Mercer ice streams, West Antarctica,
> reveal 14 regions of temporally varying elevation which we interpret as
> the surface expression of subglacial water movement. Vertical motion and
> spatial extent of 2 of the largest regions are confirmed by satellite
> image differencing. A major, previously unknown subglacial lake near the
> grounding line of Whillans Ice Stream is observed to drain 2.0 km3 of
> water over ~3 years, while elsewhere a similar volume of water is being stored
> subglacially. These observations reveal a widespread, dynamic subglacial
> water system which may exert an important control on ice flow and mass
> balance.
>
>
> Fast flowing subglacial ice streams are important indicators of climate
> change and will be helpful in improving our predictions of sea level
> rise. The author of this paper was quoted by New Scientist as following:
>
>
> > We didn't realise that the water under these ice streams was moving in
> > such large quantities and on such short time scales. We thought these
> > changes took place over years and decades, but we are seeing large changes
> > over months," says Helen Fricker at the University of California San Diego's
> > Scripps Institution of Oceanography in the US, who led the study.
> >
> >
>
> Uh, oh. Most of the worry was concerning Greenland and it has been
> generally assumed that Antarctica would as it has in past deglaciations lag
> the Northern Hemisphere. This appears to challenge that assumption.
>
>

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David W. Opderbeck
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