Clues In The Arctic

The U.S. Coast Guard icebreaker Healy has been plowing through the frozen expanse that is the Arctic Ocean north of Alaska in search of answers about climate change. CBS News Correspondent Jerry Bowen reports.

"The Arctic Ocean is one of the few places we know little about, says Capt. David Visneski. "We know more about the moon in some places than we do about the Arctic Ocean."

The hostile, forbidding appearance of the Arctic would seem to make it the last place to look for clues to climate change, and yet the reality is the environment here is quite fragile: A place where even a small increase in temperatures can have a dramatic impact.

"We think it's vulnerable and there are changes happening already," says chief scientist Lee Cooper.

In the last 100 years, parts of the Arctic have warmed by 10 degrees Fahrenheit, 10 times the global average. The icepack, home to the world's polar bears, has retreated by 15 percent in just two decades. Its thickness reduced by almost half.

"In my lifetime or my daughter's lifetime, the Arctic might be ice-free," Cooper says.

One predictor of change is the minute shrimp-like crustacean that lives on the ocean floor and an important member of the Arctic food chain, which Healy researchers found is scarcer than expected.

"With climate change these animals will be absent," says Sharon Smith, of the University of Miami. "We'll be catching animals one-tenth the size, and they're so small they won't be able to support the large birds and mammals that are here now."

Work on this research ship, funded by the National Science Foundation, is dangerous. Sampling equipment, costing hundreds of thousands of dollars, is in constant danger of being snagged and lost.

Samples tell researchers if the Arctic's retreating icepack and thawing tundra ashore are releasing more carbon dioxide, accelerating the greenhouse effect and global warming.

"Today it's raining out, not snowing," says oceanographer Lou Codispoti. "And I don't remember seeing much rain up here."

Codispoti says the environment has changed dramatically since his first research cruise here nearly 40 years ago.

"On the first day of this cruise, I saw thunderheads off the Alaskan coast," he says. "I never seen them before."

And what concerns him most is the rate of change. Ice core samples show a similar warming happened within a few years 1,000 years ago.

Known as the "medieval warm period," it opened the northern latitudes to agriculture, triggered a population explosion, and cleared the way for the Vikings to start exploring through ice-free seas. Good back then, but now?

"When you think about a planet with 6 billion people and our agriculture and you think about the implications if we had rapid climate change like that again, the downside risk of that is as bad as the downside risk of terrorism," says Codispoti.

No question the top of the world is a much warmer place. The mystery is whether the change is permanent and whether man's role is casual or a major cause.