Wednesday, August 13, 2008

Elephant seals join fight against climate change

From: Reuters


SYDNEY (Reuters) - Elephant seals swimming under Antarctic ice and fitted with special sensors are providing scientists with crucial data on ice formation, ocean currents and climate change, a study released on Tuesday said.

The seals swimming under winter sea ice have overcome a "blind-spot" for scientists by allowing them to calculate how fast sea ice forms during winter.

Sea ice reflects sunlight back into space, so less sea ice means more energy is absorbed by the earth, causing more warming.

"They have made it possible for us to observe large areas of the ocean under the sea ice in winter for the first time," said co-author Steve Rintoul from Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO).

Conventional oceanographic monitoring from ships, satellites and drifting buoys, cannot provide observations under sea ice.

"Until now, our ability to represent the high-latitude oceans and sea ice in oceanographic and climate models has suffered as a result," said Rintoul, who also works with the Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart.

The elephant seals have provided scientists with a 30-fold increase in data recorded in parts of the Southern Ocean, said the study by a team of French, Australian, U.S. and British scientists and published in the Proceedings of the National Academy of Sciences.

Between 2004 and 2005, the seals swam up to 65 kilometers (40 miles) a day, supplying scientists with 16,500 ice profiles. The seals dived to a depth of more than 500 meters (1,500 feet) on average and to a maximum depth of nearly 2 km (a mile).

"If we want to understand what's going to happen to climate in the future we need to know what the sea ice is going to do. Will there be more or less and will it form more or less rapidly?" Rintoul told Australian Broadcasting Corp. radio.

The experiment involved 85 seals with sensors attached to their heads.

"They measure temperature and salinity as a function of depth as they dive down and up through the water column," he said.

"From that information we can determine what the ocean currents are doing and so they provide us with a very detailed record of how temperatures and salinity's changed," he added.

The polar regions play an important role in the earth's climate and are changing more rapidly than any other part of the world, with the Southern Ocean warming more rapidly than the global ocean average.

Sea ice not only affects the amount of energy reflected back into space, but also the amount of dense water around the Antarctic which drives ocean currents that transports heat around the globe.

Sea ice also provides a critical habitat for krill, penguins and seals.

(Additional reporting by David Fogarty; Editing by David Fogarty)

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