The Weddell Sea Expedition will bring together world-leading glaciologists, marine biologists, oceanographers and marine archaeologists on the S.A. Agulhas II, one of the largest and most modern polar research vessels in the world.
The aims of the expedition are to investigate the ice shelves around the Weddell Sea – in particular, the Larsen C Ice Shelf from which a giant iceberg broke off in July 2017 – to document the rich and diverse marine ecosystem in the western Weddell Sea, and to attempt to locate and survey the wreck of Sir Ernest Shackleton’s ship Endurance which was crushed by the ice and sank in 1915.
The Weddell Sea was discovered almost 200 years ago in February 1823 by the British sailor and navigator James Weddell. Since then, only very few expedition ships have ever sailed so far south because of the difficulties in penetrating the thick pack ice which covers the sea throughout the year. However, the study of ice shelves around the Weddell Sea is timely and of vital importance because they affect the mass-balance and stability of the Antarctic Ice Sheet, as well as worldwide ocean current circulation. Ice shelves buttress and restrain ice flowing from the interior of the continent. If ice shelves thin, or break up and retreat, then ice flow from inland accelerates, and more ice mass is lost, contributing to global sea-level rise. Melting at the base of ice shelves and calved icebergs also release fresh water, which can inhibit the generation of very dense Antarctic bottom water, one of the major drivers of the thermohaline circulation of the oceans.
The expedition research team will be led by Professor Julian Dowdeswell, the director of the Scott Polar Research Institute at the University of Cambridge. He will be using autonomous underwater vehicles (AUV), provided by the American company Ocean Infinity, to make upward-looking multibeam echo-soundings to investigate the underwater shape of the ice-shelf base, the roughness of which is a vital parameter in numerical modelling of future ice-shelf stability. The seafloor beneath the ice shelf will also be imaged to assess ice-shelf stability through time.
South African oceanographers from the University of Cape Town and Nelson Mandela University will take measurements of the salinity and temperature of the water column adjacent to the floating ice shelves to assess the modern oceanographic setting and melt rate, while researchers from the Nekton Oxford Deep Ocean Research Institute will sample deep sea marine life, and perhaps discover species new to science. Co-ordinating with the underwater research, a team from the University of Canterbury in New Zealand will use specially equipped aerial drones to measure sea ice thickness, and help the S.A. Agulhas II navigate through the dense pack. Back in the UK, the RGS-IBG is the education partner for the expedition, and will be communicating the scientific work to schools and students both in the UK and beyond.
The Weddell Sea is one of the most pristine marine ecosystems in the world. The area is a unique habitat known for its outstanding biodiversity, including emperor and Adélie penguins, and multiple species of seals and whales. Living just below the sea ice are vast swarms of krill, and far below on the seafloor the nutrient-rich benthic ecosystems contain an array of creatures, such as glass sponges and cold-water corals. The area is currently under consideration as a marine protected area by the Commission for the Conservation of Antarctic Marine Living Resources, and the Weddell Sea expedition will gather vital baseline data to assist in the long-term protection of this globally important environment.
The challenges facing the researchers taking part are immense. Sea ice conditions may thwart attempts to navigate south to the Larsen C Ice Shelf and find the wreck of Endurance, so the research team has prepared multiple contingency plans. Sending AUVs under the ice shelves is hazardous and must be carefully planned, otherwise there is a risk that they may be trapped or lost under the ice. Also, the track of the huge A-68 iceberg is unpredictable and has interrupted the usual movement of sea ice northwards along the eastern side of the Antarctic Peninsula. The expedition is using the latest satellite remote sensing technology to monitor the iceberg and the sea ice to guide the S.A. Agulhas II and decide where research should be best undertaken.
Whatever extreme conditions the Weddell Sea expedition faces, the international team of scientists, technicians and logistics experts are ready and well prepared for the task. We want to share our amazing journey with the readers of Geographical (visit the website for regular updates) and will be sending regular updates from the S.A. Agulhas II.
This was published in the January 2019 edition of Geographical magazine
Get the best of Geographical delivered straight to your inbox by signing up to our weekly newsletter and get a free collection of eBooks!