Antarctica melting?

Doug Henwood dhenwood at
Tue Dec 8 09:59:23 PST 1998

Date: Mon, 16 Nov 1998 23:10:02 -0800 To: can at From: Climate Action NOW! <climate at> Subject: Is Antarctica Disintegrating?

Is a Madhouse Century Knocking at Our Door? by Andy Caffrey (updated revision of "Antarctica's 'Deep Impact' Threat," originally published in Summer 1998 Earth Island Journal)

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 shelf.

"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 percent of the world's ice. About 13.5 percent 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 degrees 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 percent 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 Ronne-Filchner. More than half of Antarctica's ice drainages pour into these two West Antarctic bays.

If Ronne or 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 percent 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 percent of the world's ice suddenly melted, or broke up and melted. If the ice distribution was similar to today (90 percent over Antarctica; 10 percent 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.

Madhouse Century knocking?

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 four-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, with an area of 2,751 square miles! 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 ice berg 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 percent 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. Please send SASE or a contribution to cover our expenses.

updated November 16, 1998 ***************************************** Andy Caffrey Director, Climate Action NOW! P.O. Box 324 Redway, CA 95560

707/923-2114 can at Climate Action NOW! (both under construction)

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