North Pole Watering Hole

The thick ice that covers the Arctic Ocean at the North Pole has melted, leaving a mile-wide stretch of water at the top of the world.

North Pole visitor Malcolm McKenna, a paleontologist at the American Museum of Natural History, tells CBS News Correspondent Bobbi Harley, "We should stop arguing about whether global warming is occuring... and refocus on what to do about it."

McKenna had never been to the North Pole until last month. He expected a frozen wonderland. Instead he and his wife snapped a picture of something entirely different.

"We arrived at the pole and various instruments said we were at the pole and here we are in open water which was a bit of a surprise," he said.

The water could be the result of global warming, although there is a debate among experts about the cause.

CBS News Correspondent Bobbi Harley reports NASA's James Hansen, an influential expert on the theory of global warming, is not surprised.

Not only the area of sea ice has decreased but also the thickness of the sea ice and its decreased by at least a couple of feet in the last 20 years, so it's a significant change," he said.

Hansen is suggesting a new strategy to combat warming: reducing aerosole, methane and diesel emissions.

"Just reducing the amount of ozone pollution and tropospheric aerosoles, these things make a lot of sense anyway because they're harmful to human health and to agricultural productivity," Hansen said.

However, some believe it could simply be a natural occurrence rather than the result of a "greenhouse effect" caused by manmade pollution and increased concentrations of carbon dioxide in the atmosphere.

McKenna believes there's no more time for debate.

"We should stop arguing about whether global warming is occurring…and refocus on what to do about it," he said.

Satellite images of the arctic ice cap do show it has shrunk six percent since 1978. A 1999 article in the journal Science found that an area of sea ice larger than the state of Texas has melted over the past 19 years.

Because the ice is floating, the melting doesn't affect sea levels.

Scientists have said that the last time the North Pole had this much water was 50 million years ago.

While McKenna's pictures of an iceless North Pole made headlines Saturday, frequent travelers to the Pole say it's not the first time he has seen water there.

"In 1996 I was up there," said Lars Wikander, president of Quark Expeditions. "We were a little bit disappointed because when we reached 90 degrees north, there was open water."

For oceanographer James C. McCarthy, who visited the pole earlier this month on a tourist cruise, the disappearing ice was a cause for concern. Passengers aboard the cruise were shocked to find water when there has long been only ice.