Just how cold can the Antarctic deep seas get?

Scientific knowledge of the deep seas surrounding the Antarctica is minimal at best, which is why new research missions are valuable to increasing our knowledge of the area. One such recent mission has revealed that the Antarctic deep sea is getting colder, and that this drop ...

Scientific knowledge of the deep seas surrounding the Antarctica is minimal at best, which is why new research missions are valuable to increasing our knowledge of the area. One such recent mission has revealed that the Antarctic deep sea is getting colder, and that this drop in temperature may have important implications for the circulation of the oceanic water masses.

This is the first result of the three-month Polarstern, a research expedition of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association in Germany that has just ended in Punta Arenas, Chile. Not far from Punta Arenas are the deep waters of the Scotia and Weddell seas, which are some of the least explored parts of the world's oceans.

Directed by Dr Eberhard Fahrbach, oceanographer at the Alfred Wegener Institute, the southern expedition brought together 58 scientists from 10 countries. Together they studied ocean currents as well as the distribution of temperature, salt content and trace substances in Antarctic sea water. 'We want to investigate the role of the southern ocean for past, present and future climate,' said Dr Fahrbach.

Because of the sinking masses from the ice sheets, the seas around Antarctica are thought to play a major role in global climate. 'While the last Arctic summer was the warmest on record, we had a cold summer with a sea-ice maximum in the Antarctic. The expedition shall form the basis for understanding the opposing developments in the Arctic and in the Antarctic,' explained Dr Fahrbach.

The expedition's results are corroborated by same-time satellite images taken during the Antarctic summer. However, trends can only be determined after several years, and so the data collected during the Polarstern expeditions alone will not be sufficient to discern long-term developments.

To reinforce the work conducted aboard the research vessel, autonomous measuring buoys were used to assess whether the cold Antarctic summer is really the start of a new trend or a one-off occurrence. These buoys can either be moored at the seafloor or be allowed to drift freely, and their use can provide oceanic data for several years.

'As a contribution to the Southern Ocean Observation System we deployed, in international cooperation, 18 moored observing stations, and we recovered 20. With a total of 65 floating systems that can also collect data under the sea ice and [that] are active for up to 5 years, we constructed a unique and extensive measuring network,' said Dr Fahrbach.

In addition to the mission to gather information, efforts were also made to help raise awareness among the public, especially young people, of environmental processes, as well as interest in science and research. To this end, two teachers were recruited to work aboard the Polarstern, and actively participate in the research. They then communicated their experiences back to pupils, colleagues and the media via the Internet and telephone.

'We will bring home many impressions from this expedition, and we will be able to provide a lively picture of the polar regions and their impact on the whole earth to the pupils,' commented Charlotte Lohse, a teacher at the Heisenberg-Gymnasium in Hamburg, Germany.

Countries

Germany