Global Warming

Captain Cook's detailed 1778 records confirm global warming today in the Arctic

in the summer of 1778, when Capt. James Cook tried to find a Western entrance to the route, his men toiled on frost-slicked decks and complained about having to supplement dwindling rations with walrus meat.

The British expedition was halted north of the Bering Strait by "ice which was as compact as a wall and seemed to be 10 or 12 feet high at least," according to the captain's journal. Cook's ships followed the ice edge all the way to Siberia in their futile search for an opening, sometimes guided through fog by the braying of the unpalatable creatures the crew called Sea Horses.

More than two centuries later, scientists are mining meticulous records kept by Cook and his crew for a new perspective on the warming that has opened the Arctic in a way the 18th century explorer could never have imagined. The results, published this month in the journal Polar Geography, confirm the significant shrinkage of the summer ice cap and shed new light on the timing of the transformation.

From the time of Cook until the 1990s, you more or less could count on hitting the ice somewhere around 70 degrees north in August. Now the ice edge is hundreds of miles farther north.

That meshes with modern observations that confirm rapid shrinkage of the Arctic ice pack over the past three decades, Overland said. The total volume of ice in summer is now 60 to 70 percent lower than it was in the 1980s, while Arctic temperatures have increased at twice the rate of the rest of the planet as a result of rising greenhouse-gas levels.

With more melting in the summer and delayed freezing in the fall, the once-elusive Northwest Passage is now navigable for private yachts and commercial vessels.