Re: [Phys-l] global temperatures

[Hugh Haskell <hhaskell@mindspring.com>]

At 21:55 -0500 04/04/2009, David T. Marx wrote:
> although
> the warmer ocean is melting ice along the coasts, that the overall
> thickness had increased over those previously mentioned decades.  I think
> there was also a mention of structures from the 1960s that are now buried
> under tens of feet of ice.

I doubt that finding man-made structures originally built on the 
surface now "tens of feet" below that surface is any indication of 
thickening of the ice pack in Antarctica. Two things will cause 
structures to "sink" below the surface--First, since they are heated 
objects (living and working quarters, mostly), they will melt the ice 
below them and slowly sink, and second, new snow will pile up on top 
of them, gradually burying them. I was in the Antarctic in the early 
sixties, when many of the structures referred to above were being 
built. The structures they replaced were below the surface, and so 
minimze the piling up of snow on the new structures, they were built 
in trenches excavated from the ice and then covered so they presented 
a minimum face to the wind and snow being blown across the surface.

This snow is mostly not new snow. Antarctica is a desert, with 
relative humidity routinely less than 10%, so most of the snow that 
falls in any region, especially on the polar plateau is not new snow, 
but snow being blown from other areas.

I spent some time at Byrd Station, on the Eastern slope of the lands 
that feeds ice onto the Ross Ice Shelf. At the time, the buildings, 
which were built on the surface and only intend to last a few years 
had sunk completely below the surface and one could see the cracks in 
the walls due to the uneven sinking. Water dripped most everywhere 
from the melting ice, and ice stalactites were common in any unheated 
area. That was nearly fifty years ago, and those structures have been 
long since abandoned for more modern and long-lasting structures.

With regard to what is happening to the ice pack there, there is a 
lot of misinformation floating around, even among scientific circles. 
But the coastal ice is certainly in big trouble. The Larsen Ice 
Shelf, located on the east coast of the Antarctic Peninsula is gone, 
and other ice shelves in the Weddell Sea area are in danger. Just a 
couple of days ago, an ice bridge holding a large chuck of ice to a 
couple of Islands broke up, meaning that the shelf will likely become 
a massive iceberg. The shelf is part of the larger Wilkins shelf 
which is in full retreat, and is likely to disappear within a few 
years, helped by the loss of the land-locked ice shelf that was 
holding it back 
(<http://www.reuters.com/article/environmentNews/idUSTRE5332BU20090404>).

Inland, especially on the large Eastern Ice Pack, which holds the 
majority of the Antarctic ice, the picture is murkier, but a recent 
studies published in "Nature," indicates that the western ice sheet 
is melting faster than had previously been thought. It's imminent 
disappearance is not expected, however--it is simply too large to 
completely melt in less than a few centuries. But there seems to be 
some evidence that the eastern sheet is growing somewhat, although 
probably not enough to offset the losses on the western side, most of 
which are "floating ice"--that is, ice that is underlain by water 
rather than land.

Here is a blog that gives some of the uncertainty about the Antarctic 
situation: 
<http://blogs.edf.org/climate411/2008/01/22/ice-shrinking-or-growing/>.

One of the factors that makes Antarctica problematic as an indicator 
of the extent of global warming is the fact that it is ringed by an 
unbroken stretch of ocean, and the air circulation above that stretch 
of ocean is a virtually continuous strong westerly flow that keep the 
warmer air from the north side of the flow from reaching the 
continent. A similar current in the ocean also blocks access to the 
continent of the warmer northern water.

Nevertheless, it appears that predictions of large gains of ice 
volume in Antarctica are optimistic.

Hugh

--
Hugh Haskell
mailto:hugh@ieer.org
mailto:hhaskell@mindspring,.com

So-called "global warming" is just a secret ploy by wacko 
tree-huggers to make America energy independent, clean our air and 
water, improve the fuel efficiency of our vehicles, kick-start 
21st-century industries, and make our cities safer. Don't let them 
get away with it!!

					Chip Giller, Founder, Grist.org