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Tuesday, February 23, 2010



by Andy Caffrey, Climate Action Now
Argentina's Antarctic base camp on the Larsen Ice Shelf had been rattled by 
nonstop ice quakes when the radio crackled, "Rudy, something's happening, the 
ice shelf is breaking!"
Rodolfo del Valle, director of geoscience at the Argentine Antarctic Institute  
got in an airplane and flew toward the Larsen A ice shelf which extends along the  
east side and toward the tip of the Antarctic Peninsula. Previously as thick as 
1,000 feet in places it was now in little pieces that "looked like 
polystyrene that had been broken by a little boy." A 40-mile crack had cut across 
the entire ice shelf from the mountains down to the Weddell Sea. An iceberg 
48 miles long and 23 miles wide had also been unleashed by the collapsing ice 
"I was astonished," said del Valle. "And then I cried. We know that the first 
step in the melting of the west Antarctic ice sheet could be the destruction 
of the ice shelf.
        --Paraphrased story recounted by Newsweek, April 3, 1995

The Larsen B appears to have begun the process of breakup, receding past its 
historical minimum extent, and past the point where recent modeling suggests 
it can maintain a stable ice front.

A new embayment is occurring along the seaward edge of the part of the ice 
shelf where melt ponding is most commonly observed.
Monitoring of the Larsen ice shelves over the last few years has shown that 
melt ponding regularly occurs north of Cape Disappointment, but is seen much 
less frequently south of there.
Melt ponds were also observed over the entire Larsen A ice shelf
prior to its breakup, and are observed on the Wilkins and George
VI ice shelves, both of which are suspected of currently undergoing
slower irreversible retreats.
               --24 March 1998, National Snow and Ice Data Center

Antarctica is covered by 90% of the world's ice. About 13.5% of that lies over 
West Antarctica, which is separated from the east by the Transantarctic Mountains. 
The Antarctic Peninsula extends from West Antarctica toward Tierra del Fuego. 
It is here that the greatest recorded warming on the planet has occurred in the 
last half century. In the past few decades, this region has warmed by 4.5 °F.
Every winter, Antarctica's four-foot thick sea ice expands to cover an area 
twice the size of the continental US. This pushes the region's winter 
temperatures lower, as ice reflects more of the sun's energy back into space 
than do dark seas.

The ice on East Antarctica is estimated to be between 11 and 17 million years 
old In the west, it's mostly less than 600,000 years old. While the eastern 
ice sits in a bowl of mountains, most of  West Antarctica's ice is anchored 
hundreds or thousands of feet below sea level - on a mixture of glacier-
pulverized rock and water that has the consistency of toothpaste.
In 1992, scientists discovered active volcanoes hidden under the ice of West 
Antarctica. They discovered one that is four miles across and rests inside a 
14-mile-wide caldera. Above these volcanoes, giant ice streams - several times 
the size of the Amazon - flow toward the ocean hundreds of times faster than the
surrounding ice. If these streams were unleashed, they could collapse the 
surrounding ice sheet, possibly leading to its obliteration.
In the early 1960s, scientists began to ask what would happen if the West 
Antarctic ice sheet were to break up and melt. They estimated that there would 
be a global 20-foot sea-level rise in an amazingly short period of time - 20 years 
or so. (After all, we are talking about nearly 10% of the world's ice.
Antarctica has a few giant ice shelves and several smaller ones that gird most 
of the continent (an ice sheet becomes an ice shelf when it expands into the ocean). The Larsen ice shelf runs up the east side of the peninsula, 
while two other large ice shelves cover two enormous bays - the Ross and the 
Ronne-Filchner. More than half of Antarctica's ice drainages pour into these two 
West Antarctic bays.
If the Ronne or the Ross begin to disintegrate as Larsen is doing right now, 
then the plug for all of these ice streams will be removed (ice shelves 
surround 95% of Antarctica, retarding the outward motion of the ice streams), 
and the ice which sits above the continent (as opposed to that anchored below 
sea level) will move into the ocean, raising sea level.
No one knows how the bulk of West Antarctica's ice sheet is anchored. 
Is it anchored by the archipelago it overruns, or is it anchored laterally 
to the Transantarctic Mountains? If the latter, a sea level increase from 
global warming factors could lift the West Antarctica ice sheet enough to snap 
the "moorings" to the Transantarctic Mountains.
The August 1995, Scientific American reported that scientists in the Bahamas 
had discovered that the last ice age began 120,000 years ago with something 
they called the "Madhouse Century." At that time, sea level was the same as 
it is now, CO2 levels were similar, and global climate was just a little colder. 
Something happened to trigger a catastrophic 20-foot sea-level increase -
immediately followed by a 50 foot decrease! - all in just 100 years!!! Then, 
the Ice Age was off and running for 100,000 years.

If sea levels only 120,000 years ago were about the same as they are now, then 
the global ratio of ice-to-water globally was probably similar to what it is
today. Which means that 12% of the world's ice suddenly melted, or broke up and 
melted. If the ice distribution was similar to today (90% over Antarctica;
10% over the rest of the planet), there is one persuasive and chilling explanation 
for the advent of a Madhouse Century: West Antarctica broke up.

In the August 1995 Scientific American, Christina Stock reported how "for a 
geologic nanosecond-a century, in other words - some 120,000 years ago, the 
earth underwent climatic havoc."
New findings show that sea level records, imprinted in limestone of the Bahama 
Islands, rose 20 feet above that of today and then plunged to at least 30 feet 
below modern levels. These erratic 100 years came at the close of the last 
interglacial era, a time when the climate was somewhat similar to ours.
"Maybe there is a threshold for warming that, once exceeded, starts to throw 
climate into a series of barrel rolls," speculates Paul J. Hearty, a geologist in 
Nassau. "If we continue to pump carbon dioxide into the atmosphere, are we going 
to warm the earth and trigger sea level events like those that happened 120,000 
years ago?"
Hearty and his colleague A. Conrad Neumann of the University of North Carolina at 
Chapel Hill postulate that sea level was rising slowly as a result of normal 
interglacial warming when something pushed the polar ice field beyond a critical 
point and ice surged into the ocean - an idea proposed in 1980 by J. T. Hollin of 
the University of Colorado at Boulder. When the seas receded, presumably due to a 
rapid ice formation at the poles, sand from lagoons in the Bahamas blew over the 
forests and entombed now-fossilized palm trees in dunes. Hearty and Neumann 
reason that the water must have withdrawn suddenly, followed by raging storms.

Researchers agree that sea level rise has quickened during the past century, along 
with atmospheric warming, and the coastal erosion and flooding are a reality. 
Ancient and modern data suggest that half of the planet's population - those 
people living in coastal areas - may be the first to feel the impacts of the 
next Madhouse Century.

The Spring 1998 issue of the Earth Island Journal reported that British 
scientists feared the "critically unstable" Larsen B ice shelf "could break 
apart in as little as two years, triggering unpredictable weather events around 
the world. In the late 1980s, major ice shelf disintegrations dumbfounded 
scientists. The Wordie ice shelf, on the western side of the Antarctic Peninsula
disappeared. An enormous mega-berg covering hundreds of square miles broke off of 
the Ross ice shelf in October 1987.

Several ice shelves on the western coast of the peninsula have now vanished. 
Then in January 1995, an iceberg the size of Rhode Island broke off as the 
Larsen A ice shelf disintegrated. In Newsweek, British Antarctic Survey 
glaciologist David Vaughn explained that the "ice shelves 'have been around 
for a very, very long time'; that they are now piles of ice cubes leaves no doubt
that Antarctica is experiencing 'regional warming.'"

Even though Antarctica is unimaginably cold, warming waters prevent the 
development of 4-feet-thick sea ice which buffers the enormous ice shelves 
from the raging polar winter storms blowing off the southern oceans. 
Geophysicist Charles Ebert of the State University of New York at Buffalo 
explained in Newsweek that the lack of ice shelves could cause melting of 
continental ice since the ice shelves cool the ocean winds that blow onto the
continent. Without intact ice shelves, winds blowing over Antarctica will be 
warmer than usual, said Ebert. "If the winds melt even a tenth of the continent's 
ice, sea levels worldwide would rise 12 to 30 feet."

Then, in February of 1998, another mega-berg, this one 25 miles long and 3 miles 
wide broke off the Larsen B ice shelf. British Antarctic Survey and the 
University of Colorado-based National Snow and Ice Data Center scientists 
predicted that the entire 4,800-square-mile, Larsen B ice shelf was nearing 
its stability limit. According to the Environmental News Network, "researchers 
believe it has retreated too far to be able to brace itself against the rocky 
peninsulas and islands that flank it. If the model is correct, the ice shelf will continue to crumble rapidly beginning
early (in 1999)."
"The warming trend appears to be related to a reduction in sea ice," said Ted 
Scambos, a research associate at the Cooperative Institute for Research in 
Environmental Sciences. "The question now is what is causing the reduction."

While scientists were pondering the fate of the Larsen ice shelf, Science 
magazine published a report in July 1998 which announced that satellite photos 
from 1992 to 1996 showed that one of West Antarctica's crucial ice streams, 
the Pine Island Glacier, is shrinking. "It is important because it could lead 
to a collapse of the West Antarctic Ice Sheet," said study leader Eric Rignot,
a radar scientist at the Jet Propulsion Laboratory in Pasadena. The glacier 
"is really a fast-moving ice stream, taking accumulated snow from the interior 
of the ice sheet and spitting it into the ocean in the form of ice," Rignot 
told Reuters.

Reuters reported that Richard Alley, a glaciologist at Penn State University,
"said if the glacier retreated too far it would allow too much ice to escape, 
causing a collapse of the shelf."

"It would make a hole in the side of the ice sheet and the remaining ice would 
drain through that hole," said Alley. "We are not saying it will probably happen, 
but it is possible, and if it does, it will affect a lot of people." 
Rignot speculated that warmer waters are also causing this glacial melting, 
which is in a different region from the Antarctic Peninsula.

In the early Fall of 1998, the media played up a story that a team of British, 
Dutch and American scientists who have been measuring the continent's ice sheet 
for THE LAST FIVE YEARS (emphasis mine), had concluded that the continent's ice 
was very stable. The point of the report was that the minimal increase of sea 
levels this past century was unlikely to have been caused by melting Antarctic ice.

In the same articles reporting this story, however, reporters also mentioned that 
the biggest iceberg of all had broken off the Ronne ice shelf! 
This astonishing ice berg, 92 MILES LONG AND 30 MILES WIDE IS THE SIZE OF DELAWARE,
This one iceberg is more than half the size of the entire Larsen B ice shelf. 
The Ronne-Filchner ice shelf is about the size of Texas and is the second largest 
ice shelf in Antarctica.  So imagine a chunk the size of Delaware breaking off of 
an ice sheet the size of Texas. By comparison, the February 1998 Larsen iceberg
that concerned everyone so much had an area of 75 square miles.

Unlike the Larsen ice shelf, the Ronne-Filchner is one of the two ice shelves 
that hold back half of the entire continent's ice-stream drainages. If it should 
disintegrate completely, so shall civilization. It's plain and simple. This is 
one threshold that absolutely can not be crossed. If it means shutting down the
automobile, oil and coal industries, so be it. The ice streams of Antarctica don't 
give a damn about inconvenienced, automobile-addicted Americans. Nature bats last.

This threshold is one that requires an all-out emergency effort to forestall. 
We can not wait until we have more proof. That's a fool's wager. The week before 
the November 1998 global warming treaty negotiations in Buenos Aires, Nature 
magazine published a call from scientists from several Western nations to begin a 
crash program to develop clean energy that would rival the Manhattan Project and 
the Apollo mission to the moon. They warned that global warming will soon become 
the environmental equivalent of the Cold War. The world is still increasing its 
reliance on fossil fuels! Only 20% or less of today's energy comes from
carbon-free sources.

Since 1995, Climate Action NOW! has been calling for a War Effort to convert 
the economic infrastructures of the world's industrialized nations away from 
fossil-fuel and nuclear dependency. We have prepared a radical ten-point proposal 
for how to make such a conversion on the scale required of us by nature, and soon 
enough to avert catastrophe. It's called the U.S. Citizens Mandate for Climate 
Stabilization and Community Well Being and is available on the Internet at: 
or by writing to Climate Action NOW!, P.O. Box 324, Redway, CA  95560. 

Andy Caffrey, Director, Climate Action NOW!
P.O. Box 324, Redway, CA  95560

(updated revision of "Antarctica's 'Deep Impact' Threat,"
originally published in Summer 1998 Earth Island Journal)


FredT said...

Tenney, something went wrong when pasting... it looks ugly, right columns were lost !

Fred said...

Well, THAT bunch of wise actions didn't happen.

Tenney Naumer said...

Dear Fred,

If you only knew the work I had to do with this text to get it this good. I couldn't really cut and paste it.

10in10 -- nope! Sure didn't!

jyyh said...

If the discontinuities in the prehistorical weather proxies are dismissed as "statistical outliers" that have no relation to historical extreme events and that have no neat explanations in conventional physics, it is no wonder that conventional projections to the future in climate models are too modest and inaccurate when it comes to abrupt changes in the weather or even climate.

Tenney Naumer said...

Did you notice that this was written in 1998?