The last 25 years of satellite observations are not long enough to determine how a large glacier, such as Thwaites, responds to long-term and near-term changes in the ocean and atmosphere. As a result, records of glacier change from the pre-satellite era are required to build a holistic understanding of glacier behavior. Ocean-floor sediments deposited at the retreating grounding line and further offshore contain these longer-term records of changes in the glacier and the adjacent ocean. Understanding of topography of the seafloor and how it influences ocean circulation near Thwaites Glacier is also needed to assess the glacier’s stability. Consequently, this project focuses on the seafloor, offshore from Thwaites Glacier, and the history of past glacial and ocean change that are recorded in the seafloor sediments.

Uncertainty in model projections of the future of Thwaites Glacier will be significantly reduced by cross-disciplinary investigations seaward of the current grounding line. Sedimentary records and glacial landforms preserved on the seafloor will allow reconstruction of changes in drivers and the glacial response to them over decades to millennia, thus providing reference data that can be used to evaluate the reliability of models. Such data will provide insights on the influence of poorly understood processes on marine ice sheet dynamics. Research activities are aimed at establishing boundary conditions seaward of the Thwaites Glacier grounding line. Records of external drivers of change and improved knowledge of processes leading to collapse of Thwaites Glacier will aid in determining past change in grounding line migration and conditions at the glacier base. These objectives will be achieved through high-resolution geophysical surveys of the seafloor and analysis of sediments collected in cores from the inner shelf seaward of the Thwaites Glacier grounding line using ship-based equipment, and from beneath the ice shelf using a corer deployed through the ice shelf via hot water drill holes.


L. Welzenbach

THOR fieldwork




L. welzenbach

L. welzenbach

Public Engagement


THOR PI Rob Larter is quoted in TIME following the recent PNAS publication on Marine Ice Sheet Instability.

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Linda Welzenbach’s pictures from NBP1902 are featured in another WIRED article about the AUV HUGIN.

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THOR Outreach specialist Linda Welzenbach’s pictures from NBP1902 are featured in the recent WIRED article (All seal images permit number FCO UK No. 29/2018):

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THOR PI, Dr. Julia Wellner talks about how diatoms help us understand the timing of glacier advance and retreat. Footage from Thwaites Glacier during NBP1902, captured by Linda Welzenbach is included.

THOR is pleased to announce the addition of PolarTrec teacher Sarah Slack to our Outreach crew. She will be participating on the 2020 Cruise on the Nathaniel B. Palmer.


THOR PI, Dr. Julia Wellner talks about her upcoming IODP cruise to Thwaites Glacier (interview begins at 10:20 minutes- 25:00- on the January 8th, 2019 Houston Matters)