While we all discuss the implications for this study -- please note that
the higher sea-level rise estimates are based on an assumption of
COMPLETE collapse of the West Antarctic Ice Sheet. The Bamber study
assumes only TWO-THIRDS of the ice sheet would flow into the sea, with
much of the rest prevented from free flow into the Southern Ocean by
underlying topography.
Dave
William Silvert wrote:
In light of the discussion that this posting has raised, I am taking the
liberty of posting the NY Times report which describes both the study
and some comments on it, which I think adds some useful perspective:
May 15, 2009
Study Halves Prediction of Rising Seas
By ANDREW C. REVKIN
A new analysis halves longstanding projections of how much sea levels
could rise if Antarctica's massive western ice sheets fully
disintegrated as a result of global warming.
The flow of ice into the sea would probably raise sea levels about 10
feet rather than 20 feet, according to the analysis, published in the
May 15 issue of the journal Science.
The scientists also predicted that seas would rise unevenly, with an
additional 1.5-foot increase in levels along the east and west coasts of
North America. That is because the shift in a huge mass of ice away from
the South Pole would subtly change the strength of gravity locally and
the rotation of the Earth, the authors said.
Several Antarctic specialists familiar with the new study had mixed
reactions to the projections. But they and the study's lead author,
Jonathan L. Bamber of the Bristol Glaciology Center in England, agreed
that the odds of a disruptive rise in seas over the next century or so
from the buildup of greenhouse gases remained serious enough to warrant
the world's attention.
They also uniformly called for renewed investment in satellites
measuring ice and field missions that could within a few years
substantially clarify the risk.
There is strong consensus that warming waters around Antarctica, and
Greenland in the Arctic, will result in centuries of rising seas. But
glaciologists and oceanographers still say uncertainty prevails on the
vital question of how fast coasts will retreat in a warming world in the
next century or two.
The new study combined computer modeling with measurements of the ice
and the underlying bedrock, both direct and by satellite.
It did not assess the pace or the likelihood of a rise in seas. The goal
was to examine as precisely as possible how much ice could flow into the
sea if warming seawater penetrated between the West Antarctic ice sheet
and the bedrock beneath.
For decades West Antarctic ice has been identified as particularly
vulnerable to melting because, although piled more than one mile above
sea level in many places, it also rests on bedrock a half mile to a mile
beneath sea level in others. That topography means that warm water could
progressively melt spots where ice is stuck to the rock, allowing it to
flow more freely.
Erik I. Ivins, a scientist at NASA's Jet Propulsion Laboratory,
described the new paper as "good solid science," but added that the
sea-level estimates could not be verified without renewed investment in
satellite missions and other initiatives that were currently lagging.
A particularly valuable satellite program called Grace, which measures
subtle variations in gravity related to the mass of ice and rock, "has
perhaps a couple of years remaining before its orbit deteriorates," Dr.
Ivins said. "The sad truth is that we in NASA are watching our
Earth-observing systems fall by the wayside as they age - without the
sufficient resources to see them adequately replaced."
Robert Bindschadler, a specialist in polar ice at NASA's Goddard Space
Flight Center, said the study provided only a low estimate of
Antarctica's possible long-term contribution to rising seas because it
did not deal with other mechanisms that could add water to the ocean.
The prime question, he said, remains what will happen in the next 100
years or so, and other recent work implies that a lot of ice can be shed
within that time.
"Even in Bamber's world," he said, referring to the study's lead author,
"there is more than enough ice to cause serious harm to the world's
coastlines."
----- Original Message ----- From: "James T. Conklin (BSME UMD 1958)"
<conk...@cfl.rr.com>
To: <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: Sunday, May 17, 2009 3:19 PM
Subject: [ECOLOG-L] Sea-Level Rise Revised
Experts have cut the sea-level rise forecast IF the West Antarctic ice
sheet were to collapse due to Global Warming. The forecast has been
revised to 10 feet in 500 years, or 0.24 inches per year.*
I recall that a sea-level rise of 20 to 50 feet had been predicted by Al
Gore and other Global Warming "experts" (fanatics) within decades. I
also
recall that the Antarctic ice sheet has been getting thicker, i.e.: not
melting.
My advice to people who have been traumatized by Al Gore's dire Global
Warming and Sea-Level Rising warnings is to start worrying about their
gums.
* Research by U.K. Natural Environment Research Council and the Colorado
University Cooperative Institute for Research in Environmental Science
and
published in the journal Science 5/15/09.
--
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