EU Satellite To Check Climate Cange Impact On Ice

BERLIN—The European Space Agency is launching a satellite that scientists hope will help them pin down the effects of global warming on the Earth's ice packs more precisely.

The CryoSat 2 mission, which starts Thursday after years of delays, will be able to pinpoint details of changes in polar ice so scientists can better understand the alarming picture of the world's retreating ice caps.

Although most scientists agree that global warming is significantly affecting the Earth's ice sheets, many also say too little is known with certainty, and that is where the CryoSat 2 mission aims to help.

"We hope to find out more about the role the sea ice plays for the climate system and more about the height of the land ice," Heinrich Miller, one of the two CryoSat project directors, told The Associated Press in a telephone interview.

"We know that it is dwindling but we don't know exactly what mechanisms are at work," the glacial scientist said.

CryoSat 2 will be the only satellite that can deliver the necessary data, Miller said.

Earlier satellites helped lay the groundwork for decades worth of research on the Arctic and Antarctic ice sheets, but those have gone out of operation without being replaced in time, Miller said.

The CryoSat mission originally was to start in 2005 but suffered a severe setback when the launcher rocket failed and the satellite was lost -- costing about euro110 million ($148 million).

In 2006, ESA decided to rebuild the satellite and launch it in 2009. Lift-off from the Baikonur Cosmodrome in Kazakhstan was then postponed several times, the last of which was in February because of technical problems with the transport rocket.

ESA says its new 700-kilogram (1,543-pound) satellite is the "most sophisticated ever to investigate the Earth's ice fields." It aims to operate for at least three to five years, hopefully longer, Miller said, and the European space agency estimates the total cost for the mission at euro140 million.

Using radar technology from 447 miles (720 kilometers) above Earth's surface, CryoSat will measure the thickness of both land and floating ice and pinpoint changes to within 1 centimeter (0.39-inch) -- impressive considering that the Antarctic ice sheet can be up to 3.1 miles (5 kilometers) thick.

Scientists know there have been significant changes in the polar regions and recent summers have seen record lows in the extent of summer ice cover in the Arctic sea, ESA said.

However, to understand more about how climate change is affecting these sensitive regions, "there is also an urgent need to determine how ice thickness is changing," the agency said.

For coastal cities and islands, the information may be a question of survival.

If all of the Earth's polar ice and glaciers were to melt, sea levels could rise up to 230 feet (70 meters), Miller said.

If only Greenland became ice-free, it would mean a 21.33-foot (6.5-meter) rise, he said.

Pessimists expect a sea rise by 2 to 3 meters (6.6 feet to 9.8 feet) by the year 2100, he said.

In its 2007 report, the world's leading climate change scientists on the Intergovernmental Panel on Climate Change (IPCC) project only some 20 to 60 centimeters (7.9 inches to 23.6 inches), but without calculating the possibility of a dramatic increase in the rate of polar ice melt.

"It is just very hard to predict this," because there are multiple reasons for the loss of ice mass -- not only warming, but also changes in sea currents, Miller said. "By repeated observation, we hope to register even small changes within a brief period of time."