From: "Skywatch International Inc." 
Subject: (Skyopen) FW: Antarctica May Be Melting, Say Researchers
Date: 5 Aug 1998 22:27:24 -0400
To: "sky open list" 



-----Original Message-----
From: Hang time55 [mailto:wbkjr@juno.com] 
Sent: Wednesday, August 05, 1998 4:24 PM
To: skypost@unix.ltlb.com
Subject: Antarctica May Be Melting, Say Researchers 


SAN FRANCISCO EXAMINER
(Distributed by Scripps Howard News Service)
(August 4, 1998 12:42 p.m. EDT http://www.nandotimes.com)


Antarctica May Be Melting, Say Researchers 

New evidence strengthens fears that Antarctica might be melting,
threatening to raise sea levels and flood low-lying areas
around the world.

At worst, scientists say, global sea levels might rise by about
20 feet over the next few centuries. Such a disaster would
drown many coastlines and submerge some Pacific islands.

Last month, in several articles in science and nature
magazines, scientists reported new data suggesting that
parts of the Antarctic ice are falling apart faster than once
thought.

The main object of concern is the West Antarctic Ice Sheet,
or WAIS. It floats above water, like an extension or "shelf"
projecting from the Antarctic continent.

    Among the scientists' findings:

    Space satellites have detected Antarctic ice changes
    that might, at worst, "be a first step toward the collapse
    of the entire West Antarctic Ice Sheet," according to the
    July 24 issue of Science.

    The European research satellites, known as ERS 1
    and ERS 2, use radar to map the distribution of ice in
    Antarctica. The satellite data show that the so-called
    grounding line -- the boundary between floating ice and
    ice atop the Antarctic continent -- "has been retreating
    inland at a rate of more than a kilometer (0.6 mile) per
    year," reports the Science article by Richard Kerr.

    Why? "Presumably because the glacier is losing mass
    by melting at its base," Kerr says. His article
    summarizes research, published in the same issue, by
    Eric Rignot of the Jet Propulsion Laboratory in
    Pasadena, Calif. Rignot was unavailable for comment.

    The West Antarctic Ice Sheet is unstable over
    geological time, judging by new evidence that it
    "wasted away to a scrap" at some unknown time in the
    last 1.3 million years, according to researchers in
    Sweden and Southern California.

    The scientists base the finding partly on fossilized
    marine organisms, diatoms, which they recovered from
    deep within the West Antarctic ice. The find shows that
    the ice-covered area was free of ice in the geological
    past.

    The finding is reported in the July 3 issue of Science
    by Reed Scherer of Uppsala University in Sweden and
    Slawek Tulaczyk of Caltech, and their colleagues.

    "Now the question is when the WAIS might disintegrate
    again as the world warms -- and how rapidly it might
    flood low-lying coasts," says a Science story
    accompanying the Scherer report.

    Slick, fine-grained sediments beneath Antarctic coastal
    ice might accelerate its outflow, speeding the rise of
    global oceans, according to research published in the
    July 2 issue of Nature. The researchers are at
    numerous universities and are led by R.E. Bell of
    Columbia University.

Environmentalists have worried about Antarctica's fate for
decades.

In the 1970s, a few researchers warned that "global
warming" might melt part of the Antarctic ice sheet, which is
several miles thick. As a result, they said, sea levels could
rise globally.

Ever since, glaciologists -- scientists who study the world's
vast outcroppings of glacial ice, from Greenland to
Antarctica -- have warred over what's really happening in
the southernmost continent.

They fall into two camps. One argues that Antarctic ice has
been relatively stable over millions of years, and is unlikely
to undergo major collapse as the planetary temperature
rises, according to geophysicist Alan Cooper of the U.S.
Geological Survey at MenloPark, Calif.

Another camp, Cooper says, argues that at least parts of the
West Antarctic Ice Shelf are highly unstable, and could
rapidly fall apart during a major warming. By "rapidly," they
mean a few centuries, extremely fast in geological terms.

Cooper -- who declines to side with either camp -- says the
public can learn more about Antarctic ice dynamics at a Web
site: www.usgs.gov/education/animations/.

While concerned by Rignot's observations, experts caution
against jumping to conclusions.

"Eric Rignot's observation does not mean that the (Antarctic
ice) collapse has started; it does not mean sea level will be
20 feet higher in 100 years," says Richard Alley of
Pennsylvania State. "The easiest reason (for saying this) is
that he hasn't watched (the glacier) very long."

Conceivably, Alley said, the glaciers might be undergoing
some very dramatic, but normal, changes that are unrelated
to global warming.

"Glaciers do odd things sometimes. They flow fast, then
slowdown. ... You could anthropomorphize them and say
they have a mind of their own," says Alley, who calls for
further research.

The new evidence impresses at least one veteran skeptic,
Barclay Kamb, a noted glaciologist at Caltech.

Originally, Kamb said, "I was rather skeptical of this idea of
(Antarctic ice sheet) disintegration, it seemed (to me) like a
play for attention, like grandiosity."

But now, he says, the evidence for rapid ice changes is
good enough that the worst case scenarios are worth
worrying about.

If the ice sheet disintegrated, "sea level would rise by about
five meters, that is, about 20 feet," Kamb says. "You'd
produce a lot of these huge 'tabular' icebergs, some as big
as the state of Connecticut."

Scherer's work impresses John Barron, a USGS-Menlo Park
geologist who studies diatoms.

"I think (Scherer has) proven his case" that the ice sheet
changes substantially over time, Barron says. "What has
been lacking is direct evidence.

"And now he has provided direct evidence that at some time
in the last 1.3 million years, there was no ice sheet over
those sites."

Meteorologist Mark Fahnestock of the University of
Maryland at College Park thinks it's too early to say whether
the ice sheet is disintegrating over the centuries, or is just
undergoing routine variations in shape and size.

But if the ice continues to melt at high speed, he says, "then
maybe we will get to the point where we would call it a
warning signal."
~~~~~~~~~~~~~~~~~end~~~~~~~~~~~~~~~~~


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