SPACE.com -- Using Radarsat, scientists can take images of the entire ice cap at extremely close resolutions.

These two Radarsat images represent an area located in the Baufort Sea, north of the Alaskan coast. Within a nine-day span, large and extensive cracks in the ice cover have formed due to ice movement (right image).

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	Using Radarsat, scientists can take images of the entire ice cap at extremely close resolutions. By Craig Linder Special to SPACE.com posted: 07:00 am ET 22 August 2000

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WASHINGTON, August 21 --- The ancient layer of ice that sits atop the world at the North Pole is slowly thawing, in some places melting so completely that patches of the open Arctic Ocean are all that remain.

United Nations-backed researchers recently announced that a hole in the icecaps has developed over the North Pole, marking what could be the first time in 50 million years that the top of the world is not covered by ice.

New Satellite to Measure Thickness of Polar Ice Caps

NASA is a little more than a year away from launching a satellite capable of making regular measurements of even the minutest changes in the thicknessof the ice capping the Arctic, Antarctica and Greenland. .

At the same time, the average thickness of the ice covering the Arctic Ocean has decreased by 42 percent over the past 22 years, according to data from the University of Bergen in Norway.

Now, NASA researchers have a new method to track the condition of the Arctic icecaps.

Using the Canadian Radarsat satellite, scientists at the Jet Propulsion Laboratory (JPL) in Pasadena, California can take images of the entire icecap at extremely close resolutions.

The technology, which takes an image of the polar region once every three days, allows NASA researchers to examine the Arctic region at resolutions of up to 328 feet (100 meters). At that resolution, the JPL team can watch as cracks develop in the icecaps.

The Arctic Ocean mapped in an unprecedented manner by scientists at NASA's Jet Propulsion Laboratory, Pasadena, California.

"This is the first time that we're able to see how many holes are opening in the ice," Ron Kwok, a senior research scientist, said. Kwok is the Radarsat project's principal investigator at JPL.

Using a method called geophysical processing system, the Radarsat system monitors sea ice in greater detail than the previous system, called passive microwave, could.

The passive-microwave technology was only able to examine the caps to 15.5 miles (25 kilometers) and was often hampered by the near-constant cloud cover over the Arctic. Radarsat technology is able to offer researchers more detail more often. Launched by NASA in 1995, Radarsat is operated by the Canadian Space Agency.

"What Radarsat did is that it allowed us to see through the clouds in high resolution," said Ted Scambos, a research associate scientist at the National Snow and Ice Data Center in Boulder, Colorado.

Radarsat permits scientists to closely watch the cracks and holes that develop in the ice. Cracks in the ice can develop nearly overnight and take approximately three days to close up. Flows of ice can move at rates of up to 25 to 30 miles (40 to 50 kilometers) in a day, Kwok said.

Using the technology NASA scientists are able to monitor the 1-mile (1.6-kilometer) wide hole in the icecap directly over the North Pole that the U.N. researchers reported finding earlier this month.

Scientists were largely surprised by the discovery, with many noting that there is usually a sheet of ice 6.5-to-10-feet (2-to-3-meters) thick over the North Pole in the summer.

"I don't believe that has happened before, though it's probably transient," Scambos said.

Kwok, however, downplayed the reports of the thawed hole, saying that summer temperature increases often create holes in the polar icecaps, though rarely at the North Pole.

"These openings open up and close, and a mile wide is not that unusual in the summertime," he said. "At the North Pole, though, that is unusual."

Scientists can not yet determine much from the hole over the North Pole, Kwok said. Because climates tend to change in cycles that can last for decades at a time, more data is needed over a longer period of time.

"We can't tell from one year's data yet," he said. But, "in the past 20 years we have seen a retreat of the ice cover."

As the polar icecaps thaw and become thinner, Kwok said, more solar radiation can enter the oceans. That radiation can then warm the seawater, which in turn can cause the icecaps to thaw more quickly. The result is a continued cycle of icecap melt, Kwok said.

"The important thing here is that the ice is an insulator of the ocean," he said. The continual weakening of that insulator, of course, means that the oceans get warmer year after year.

"There have been several earlier years of rather extensive melting at this time of year. That record of melting has been more extreme in the last few years," Scambos said. "In terms of there being a trend toward warming in the Arctic and in other parts of the world...these last 20, 25 years are warmer than the previous record."

Though some of the data may still be unresolved, Scambos said that scientists should begin to think about the situation, saying, "I think that it's time that we took notice of global warning and made plans for a future warmer world."

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