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Antarctic voyage

A firsthand look at the effects of climate change near the South Pole.

By George TombsCorrespondent of The Christian Science Monitor / May 11, 2009

Capt. Klaas Gaastra stands watch as the Dutch three-masted bark Europa transits Lemaire Channel off Antarctica.

Photos by George Tombs.

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Aboard the Europa in Antarctic waters

“Our square sails are braced right now for the changing wind that we expect ahead as we cross Drake Passage, between Cape Horn and Antarctica,” says Mike Stewart, the boatswain of the Dutch tall ship Europa. Surging along the crests of 20-foot, slate-gray waves, the Europa is taking 15 crew members and 40 sail trainees to the Antarctic Peninsula.

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The wind moans in the rigging, setting every brass hook and teak panel clanking, rattling, shivering, and heaving. Regularly thrown off balance, the men and women on board are willing to put up with discomfort to see the effects of climate change in Antarctica firsthand.

The impending collapse of the 5,600-square-mile Wilkins Ice Shelf adds a sense of urgency to the voyage. The Antarctic Peninsula, which stretches 750 miles north from the continent into Drake Passage, is arguably undergoing the fastest rate of climate change of any region on earth.

As the Europa approached Antarc­tica in late January, snow fell frequently, forming sodden clumps and then melting. Gentoo penguins leapt in the sea like miniature porpoises.

Antarctica is breathtaking. It’s a frozen desert with almost no precipitation. Along its coasts are the breeding grounds of humpback whales, seals, and penguins.

Statistically, the polar continent is just as breathtaking. Having 1-1/2 times the surface area of the United States, Antarctica contains 7 million cubic miles of ice, which has an average thickness of 1.6 miles.

Virtually an icemaking machine that has locked up 70 percent of the planet’s freshwater, Antarctica is undergoing rapid change.

According to one estimate, 550 cubic miles of Antarctic ice are calved into the sea each year, while about 407 cubic miles of compacted snow are added each year. The net loss seems slow, but the results along the water’s edge can be dramatic.

As the Europa arrives at Trinity Island in the Palmer Archipelago, humpbacks blow in the distance, and leopard, fur, and Weddell seals bask on rocks. Sharply angled pinnacle icebergs of every description loom: giant “cathedrals” of opaque bluish crystal; flat islands of ice shaped like aircraft carriers; one looks like a swallow perched on a mount.

But also evident are signs of the “great melt.”

“The breakup of several Antarctic ice shelves since the beginning of the 1970s is an important indicator of climate change in the Antarctic Peninsula,” says Ken Jezek, a geophysicist at The Ohio State University’s Byrd Polar Research Center in Columbus and a world authority on polar ice. “Removal of these ice shelves has eliminated an important restraining effect. So glaciers on the rocky interior of the peninsula are now more rapidly pumping ice into the ocean.”

Dr. Jezek is scientific lead of the Global Inter-agency International Polar Year Snapshot Year (GIIPSY), which is using earth observation satellites from several countries to measure ice thickness and ice velocity at the poles. “The basic force of gravity presses down on the ice sheet, causing it to spread,” he says. “But shear at the base and along the sides resists that spreading. The interplay between these stresses determines the motion of the ice sheet. Estimating how that interplay might change in the future could well enable us to predict the behavior of the ice sheet.”

One of the best tools for measuring the thickness and movement of ice is Radarsat-2, a satellite operated by a Canadian aerospace company. In 1997, Jezek and his team at the Byrd Center developed the first mosaic map of Antarctica using data from the first-generation Radarsat-1. They have completed other maps since. This type of mosaic provides a tremendous amount of detail, since radar penetrates cloud cover, fog, and the polar night.

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