Geological drilling mission in West Antarctica’s interior

On November 16, an international team of researchers and drilling experts will set out from Christchurch, New Zealand, for Antarctica to drill up to 200 metres into the seabed beneath the inner Ross Ice Shelf. The team aims to obtain geological records of changing sediments that reflect environmental conditions at the time of their formation in a warmer world than today. These records are expected to provide important insights into West Antarctica's past, allowing us to learn more about Antarctica's potential future contribution to sea level rise.

The Science Leadership Team (SLT) also includes micropaleontologist Denise Kulhanek from Kiel University. She will join the expedition from December until January and will be working on the analysis of the collected sediment cores to understand past changes in ocean conditions and the changes in the size of the Western Antarctic Ice Sheet. To do so, she will use the elemental composition (i.e., aluminium, silicon, potassium, iron) of the sediment measured every centimeter to determine the dominant composition of the sediment and relate this to the environment in which the sediment was deposited, open marine, under the ice shelf, or under grounded ice.

Environmental information for future predictions

Recent scientific research has shown that the warming Southern Ocean will accelerate the melting of large portions of the West Antarctic Ice Sheet (WAIS) - even today, as a consequence of the accumulation of greenhouse gases in the atmosphere to date.

If completely melted, the WAIS contains enough ice to raise sea level by up to 5 metres. However, it is not yet certain how much and how fast West Antarctic ice will melt. While parts of the WAIS appear to be highly vulnerable, it remains unclear when and under what climatic conditions the large ice shelves that stabilize the ice sheet will be lost. Finding answers to this will require sediments from regions near the center of West Antarctica that were deposited during past periods that were warmer than today. These sediments contain environmental information that is critical for the predictions but has not been accessible until now.

"We know more about the rocks and composition of the Moon than we do about the land beneath the West Antarctic Ice Sheet," says micropaleontologist Denise Kulhanek from the Institute of Geosciences at Kiel University, one of the lead scientists on the international research project, Sensitivity of the West Antarctic Ice Sheet to Two Degrees of Warming (SWAIS 2C). Since the first landing in 1969, astronauts have collected more than 2,400 rock and mineral samples from various locations on the moon. However, under the ice cover of West Antarctica, there are only 13 sites where scientists and researchers have collected geological samples. The SWAIS 2C-project will determine whether the Ross Ice Shelf and West Antarctic Ice Sheet could melt if Earth's average surface temperature is 2 °C above pre-industrial levels.

"In the Paris Agreement, we committed to keeping global average temperatures well below 2°C compared to pre-industrial conditions. Models tell us that the West Antarctic Ice Sheet will collapse once this value is exceeded. So far, however, this cannot be confirmed – simply because we do not yet have sound geological evidence that would allow us to define the behavior of the ice sheet during past warm periods," says Johann P. Klages, marine geologist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), German co-coordinator and member of the SWAIS 2C science team.

Complex sampling through ice and the ocean floor

To learn more about Antarctica's potential contribution to sea level rise, a team of drilling, engineering and research experts will travel approximately 800 kilometers by traverse and aircraft to the southeastern edge of the Ross Ice Shelf. There, they will drill up to 200 meters into the seafloor to obtain geologic records of changing deposits that reflect environmental conditions at the time they formed. The hope is that these records will provide important insights into West Antarctica's past and the future of our planet.

"We will use a custom-built hot water drill to melt a 35-centimeter-diameter hole through 590 meters of thick ice, then move through 50 meters of ocean water to the site where the ice sheet broke away from its bed and created new ocean floor," says Andreas Läufer, geologist at the Federal Institute for Geology and Natural Resources (BGR), German coordinator and member of the SWAIS 2C science team.

"There, we will then position a special sediment coring system over the hole, lower a hollow drilling system to the seafloor, and drill to depth for hopefully obtaining long sediment records from West Antarctica's past," says Darcy Mandeno of the Antarctic Research Centre in Wellington, New Zealand, leader of the drilling effort for SWAIS 2C. Field work in Antarctica will begin in November 2023 on the Kamb Ice Shelf and continue through January 2024. A second field season will begin in November 2024 on the Crary ice margin.