SYDNEY - 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).
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.
