Estimates vary on when Northwest Passage will be open all summer

ICEBREAKER CHANNEL, Northwest Passage — Satellite imagery has shown that the Arctic ice cap is thinning and already is nearly 30 percent smaller than it was 25 years ago. In the winter of 2004-05, the Arctic's perennial ice, which usually survives the summer, shrank by 280,000 square miles, the size of Turkey. This past August, a crack opened in the ice pack from the Russian Arctic to the North Pole, an event never seen before.

Arctic ice reflects sunlight; its absence may accelerate global warming. The intricate chemistry that occurs in the rich Arctic waters could go haywire with unaccustomed heat and sunlight. Whole species seem destined to disappear while others move north in their place. "People tend to think there's not much life in the Arctic. But it's an incredibly diverse ecosystem," says Gary Stern, the chief scientist on the Amundsen.

Estimates vary widely on when the passage will be open to shipping all summer because of the ceaseless warming. The Canadian Ice Service conservatively predicts the southerly drift of even a shrunken ice pack will keep the passage clogged for most of this century. Other experts predict it will be open as soon as 2020; Canada's defense agency says 2015.

ArcticNet, the Canadian university consortium organizing the voyage, believes the interwoven effects of global warming may be revealed as shipmates, from students to noted scientists, discuss their work over galley tables.

Stephane Thanassekos, 26, a French researcher pursuing his doctoral degree at Laval University in Quebec City, operates a contraption that looks like an automatic milker from a dairy barn. It has 24 cylinders that can each be controlled to collect water at a different depth, up to 3,000 feet, and a bevy of sophisticated probes.

"These measurements are used to calibrate the models that tell us, for example, when we won't have ice in the Arctic," he says. His own work calculates the survival prospects of Arctic cod, "which are right in the middle of the food chain" of the Arctic.

Jody Deming, 54, a professor at the University of Washington, studies "hot spots" in the ocean that are now being overtaken by a gradual warming.