Re: Massive ice shelf collapsing off Antarctica

On Mar 27, 11:48 pm, "Cosmin Corbea"
<cosminc@[EMAIL PROTECTED]
> wrote:
> William Hyde wrote:
>
> > The Antarctic peninsula is warming, and warming fairly seriously.
> > But yes, Antarctica as a whole is neutral to cooling.
>
> Can you explain please what do you mean by "Antarctica as a whole"? On
the
> map herehttp://earthobservatory.nasa.gov/Study/WilkinsIceSheet/the
warming
> areas of Antarctica seem to be more than twice larger than the ones that
are
> showing a cooling tendency.

The figures I recall showed most of East Antarctica as neutral
or cool, but this clearly shows that much of it is warming, and all of
West Antarctica is warming also.  I can't do the integral in my
head, but as you say it is clear that in this figure the continent as
a whole is not cooling (note the wonderful small-scale dynamics
off the Ross ice shelf, from strong warming to strong cooling and
back to strong warming in a few tens of kilometers).

If there is way to reconcile these two, it may be that the figure
you link to is of  skin temperature, while I am remembering air
temperature.  In an under-appreciated paper, Jin and Dickinson
showed that skin temperature is  rising faster than air temperature.
As this is the actual temperature of the ice
and not of the air a couple of meters above, it would seem
to be the more relevant factor in ice melt.

On the other hand, this lecture:

http://www.bjerknes.uib.no/pages.asp?id=1541&kat=7&lang=2

seems to imply that the warming has picked up lately, even in surface
air temperature, and  that while parts of East Antarctica are still
cooling, the continent as a whole now has a small but
statistically significant warming trend.

So I retract my statement.  It appears that as of now, Antarctica as a
whole cannot be said to be cooling.  Both the Antarctic peninsula and
West Antarctica are warming strongly, and while much of East
Antarctica is cooling, ever here there is now some
warming over quite large areas.  It is still a very slow warming
compared to the Arctic, as predicted.

I still don't think the Wilkins collapse is a great  thing to cite in
and of itself as evidence of global warming.  As part of a pattern,
though,  it makes a stronger argument, particularly
if the rest of the shelf goes next summer.

William Hyde