On 29 January the Polarstern started to sail with a new crew as well as new scientific and technical personnel back to Punta Arenas. From the eastern Ross Sea and along the continental margin off Marie Byrd Land geophysical profiling will connect the existing data grid of the Ross Sea to the profiles in the Amundsen Sea and Bellingshausen Sea. The researchers headed by Chief Scientist Dr. Karsten Gohl from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association want to close the currently existing large gap in data. The objective of this work is to determine the topography of the seafloor at present and in the geological past and thus create a basis for long-term climate simulations. The main area of work will subsequently be Pine Island Bay, known for the recently accelerated retreat of the Pine Island and Thwaites Glacier systems. Reconstruction of the dynamic changes in the West Antarctic ice sheet is aimed at providing a better understanding of the current changes and their possible influence on an increased sea level rise. This aim constitutes the focus of the geophysical and geological investigations. Geothermal heat-flow measurements are expected to provide insight into recent volcanic activities that may have an impact on ice-sheet dynamics. Oceanographic measurements will help in explaining one of the possible causes of the present retreat of the glaciers.
The 43 members of the team involved in the expedition that just ended was headed by geologist Dr. Rainer Gersonde from the Alfred Wegener Institute. They collected 1000 metres of sediment cores altogether (around eleven tons in weight) at 70 stations during the research cruise from Chile to New Zealand that covered 9400 nautical miles (17,000 km). The unique material will furnish for the first time detailed information on the climate history of the last 400,000 to 4 million years in this region, which has been subject to little research up to now, though it is important for climate development. Scientists from six nations, including New Zealand, will jointly examine the evolution of the Antarctic Circumpolar Current, the spread of sea ice and its influence on variations in greenhouse gas concentrations as well as melting events in the West Antarctic ice sheet and their impact on global ocean circulation using state-of-the-art methods. Another objective is to determine climate-impacting interactions between the polar South Pacific, the tropical and northern polar regions during past cold and warm periods.
Such questions relevant to the climate are also the focus of a planned deep-sea drilling project within the framework of the Integrated Ocean Drilling Program (IODP) in the Antarctic Pacific. The two ongoing expedition phases will provide the database for selecting the IODP drilling sites. Researchers from all over the world want to look as far as 40 million years back into the geological past with the deep-sea sediments to be drilled in the future.
In addition to geologists and geophysicists, biologists, chemists, oceanographers and scientists of numerous other disciplines also make regular use of the research icebreaker for their studies. This is the 50th expedition with about 200 legs altogether and a good example of the multidisciplinary approach applied on the Polarstern, which has been sailing across the Arctic, Antarctic and oceans of the mid latitudes since 1982. It provides a platform for scientists of the Alfred Wegener Institute and their cooperation partners and contributes to unravelling the complex interrelationships in the Earth system. The primary objective of the research is to understand the driving forces and fluctuations in climate cycles.
Contact
Communication and Media Department of the Alfred Wegener Institute
Folke Mehrtens
Phone: +49 471 4831 - 200
Email: medien(at)awi.de
