NASA: Arctic Melting Is 'Alarming'

This summer will go down as the hottest in the continental U.S. in 70. Scientists expect the warming to continue and warn we're running out of time to do something about it. Jerry Bowen reports.
Icebreakers crunching their way through the Arctic ice pack at the top of the world are finding more open water than ever, CBS News correspondent Jerry Bowen reports.

NASA scientists say it's all because of what they call an "alarming" rapid melting of winter sea ice — the usually permanent ice cover over the Arctic Ocean. In just the past two years, it has shrunk by 14 percent. The loss has been just at the edges, but it's still a Texas-sized loss that researchers say is linked to man-made global warming.

"Sea ice melt is actually a consequence of that warming. The fact that you have a longer melt period is also a consequence of greenhouse warming," says Josefino Comiso, a NASA scientist.

Scientists are studying ice thickness and water temperatures in the very heart of the Artic at the North Pole. Two years ago, the idea of an ice-free Arctic was a serious consideration.

"It does represent a fundamental change in our global climate. And it's a concern with any of the global warming scenarios," says James Morison of the University of Washington.

NASA climate scientist James Hansen believes the world has little time left to combat greenhouse gases. "I think we have a very brief window of opportunity to deal with climate longer than a decade at the most," he told a climate conference this week.

If nothing is done, the global warming forecasts speak of rising sea levels worldwide – 3 feet to 20 foot higher seas from Manhattan to Malibu by century's end – but disaster planners say there might still be a fix in the best-case scenario, a way to shore up America. But there's a cost.

"The estimates of what it would cost to defend or adapt the entire United States to the low estimates of rising sea levels is a couple of hundred million dollars a year over the coming century," says Rob Lempert of the Rand Corporation.

That's if policymakers take the warnings seriously. There are some who contend global warming is fiction — that the sky is not falling. But at the top of the world, something is going on: The ice is disappearing.