December 7, 2012
Warm Seas Melting Antarctic Ice Sheet Faster Than Expected
April Flowers for redOrbit.com - Your Universe Online
The West Antarctica ice sheet is melting faster than expected. An international group of oceanographers led by the University of Gothenburg has published new observations in the journal Nature Geoscience that may improve our ability to predict future changes in ice sheet mass.
The water levels of the oceans would be affected globally by a reduction of the ice sheets in Antarctica and Greenland, making it problematic that current information concerning the ocean circulation near large glaciers in West Antarctica is insufficient. Researchers are unable to predict how water levels will change in the future with any large degree of certainty.
"There is a clear reduction in the ice mass in West Antarctica, especially around the glaciers leading into the Amundsen Sea," says researcher Lars Arneborg from the Department of Earth Sciences at the University of Gothenburg.
Arneborg and his team have been studying ocean circulation in the Amundsen Sea. According to the team, West Antarctica is particularly sensitive because the majority of the ice rests on areas that are below sea level where warm water penetrates beneath the ice. This causes increased melting from underneath.
"It is therefore probably a change in the ocean circulation in the Amundsen Sea that has caused this increased melting," continues Arneborg.
Previously, scientists have been referred to studies that use high-resolution computer models.
"But there have been very few oceanographic measurements from the Amundsen Sea to confirm or contradict the results from the computer models. Nor has there been any winter data. Sea ice and icebergs have made it impossible to get there in the winter, and it isn't easy to have instruments in place all year round," he explains.
The researchers have managed to position instruments in the Amundsen Sea since 2010, enabling them to measure the inward flow of warm sea water towards the glaciers. In contrast to the model results which suggest a strong seasonal cycle, the new observations show that the warm sea water flows towards the glaciers in a more or less constant current all year round.
"This shows just how important observations are for investigating whether the models we use describe something that resembles reality. Warm ocean currents have caused much more melting than any model has predicted, both in West Antarctica and around Greenland."
The team says they will need more observations over longer periods in order to improve the models and achieve a better understanding.
"Only then will we be able to say something about how the ice masses of the Antarctic and Greenland will change in the future," concludes Arneborg.