The NERC and NSF partnership, called the International Thwaites Glacier Collaboration (ITGC), covers research across Thwaites Glacier and its adjacent ocean region; the glacier flows into Pine Island Bay, part of Amundsen Sea. ITGC is the largest joint UK-US project undertaken on the southern continent in 70 years.

Over the past 30 years, the amount of ice flowing out of this 120-kilometer-wide region has nearly doubled. Overall the glacier is the size of the island of Britain, or the state of Florida, and it straddles some of the deepest bedrock in the southern continent. Warm ocean water from the Amundsen Sea circulates under the ice, causing it to melt. Melting loosens the ice from the bedrock below, causing it to flow faster and eventually to retreat into the deeper and thicker ice areas where it is likely to speed up still more.

Starting in 2018, and over the next five years, teams of scientists will explore the ocean and marine sediments, measure currents flowing toward the deep ice, and examine the stretching, bending, and grinding of the glacier over the landscape below. The project will involve more than 60 scientists and students.

Click HERE to read why Thwaites Glacier research matters.

The schematic (right) summarizes the fieldwork and methods that are employed at Thwaites Glacier and the southern Amundsen Sea Embayment shelf. Research cruises in 2019 and 2020 gathered information about the seafloor bathymetry and subsurface to compliment the collection of sedimentary cores from the grounding-line proximal to the distal glacimarine.

Graphic by Rebecca Minzoni

Marine Sediments

Multibeam swath bathymetry systems produce maps of features on the seafloor. Around Antarctica, this type of data is used to track ice flow and retreat in the past using preserved glacial landforms exposed on the seafloor. The newest systems use high-frequency (12 kHz) sound pulses, which bounce off the seafloor through a known water depth to a source located at at the surface, that achieve centimeter- to meter-scale resolutions.

Seismic stratigraphy techniques help geologists “see below” the surface. Seismic data is generated by sound waves. Sound waves are then displayed as a reflection of the subsurface stratigraphy. THOR team scientists interpret seismic reflectors as a predictive tool for identifying locations to collect seafloor samples and to describe the historical depositional setting for Thwaites Glacier.

We have collected 220+ meters (720 feet) of sediment from a total of 94 cores on two cruises to Thwaites Glacier. End to end, that’s enough sediment to stretch across 4.5 football fields. Stacked vertically, these cores would be 1.3 times taller than the Washington Monument. To investigate how Thwaites has been changing in the recent past, the go-to is the Kasten core, which can penetrate up to three meters into marine and glacial sediments that represent the time period since the last glacial maximum - that’s thousands of years’ worth of sediment. Sometimes, in areas with lots of sediment, we will use the (appropriately named) jumbo core. A jumbo core can be deployed by relying on gravity alone (like the Kasten) or with a hydraulic piston that shoots the core liner into the sediment once it hits the seabed, recovering up to 24 meters (80 feet) of sediment and allows us to investigate further back in geologic time. When we want a glimpse of the current and very recent environment at the seafloor, we use a multicorer or a box corer. These gently penetrate the upper surface and recover the sediment-water interface - sometimes delivering lifeforms like brittle stars and sea pigs. The many meters of sediments collected during these two expeditions will be studied by several scientists across the world for years to come, and will reveal important details about Thwaites’ uncertain history. 

THOR PUBLICATIONS

Clark, R.W., Wellner, J.S., Hillenbrand, C.-D., Totten, R.L., Smith, J.A., Miller, L.M., Larter, R.D., Hogan, K.A., Graham, A.G.C., Nitsche, F.O., Lehrmann, A.A., Lepp, A.P., Kirkham, J.D., Fitzgerald, V.T., Garcia Barrera, G., Ehrmann, W. & Wacker, L. (2024): Synchronous retreat of Thwaites and Pine Island glaciers in response to external forcings in the pre-satellite era. – Proceedings of the National Academy of Sciences, 121 (11): e2211711120.

 https://doi.org/10.1073/pnas.2211711120.

Hogan, K.A., Warburton, K.L.P., Graham, A.G.C., Neufeld, J.A., Hewitt, D.R., Dowdeswell, J.A. & Larter, R.D. (2023): Towards modelling of corrugation ridges at ice-sheet grounding lines. – The Cryosphere, 17: 2645-2664.

 https://doi.org/10.5194/tc-17-2645-2023.

Lepp, A.P., Miller, L.E., Anderson, J.B., O’Regan, M., Winsborrow, M.C.M., Smith, J.A., Hillenbrand, C.-D., Wellner, J.S., Prothro, L.O. & Podolskiy, E.A. (2024): Insights into glacial processes from micromorphology of silt-sized sediment. – The Cryosphere, 18: 2297-2319.

 https://doi.org/10.5194/tc-18-2297-2024.

Marschalek, J.W., Thomson, S.N., Hillenbrand, C.-D., Vermeesch, P., Siddoway, C., Carter, A., Nichols, K., Rood, D.H., Venturelli, R.A., Hammond, S.J., Wellner, J. & van de Flierdt, T. (2024): Geological insights from the newly discovered granite of Sif Island between Thwaites and Pine Island glaciers. – Antarctic Science, 36: 51-74.

https://doi.org/10.1017/S0954102023000287.

Graham, A.G.C., Wåhlin, A., Hogan, K.A. Nitsche, F.O., Heywood, K. J. Totten, R.L., Smith, J.A., Hillenbran, C-D., Simkins, L.M., Anderson, J.A., Wellner, J.S., Larter, R.D. (2022). Rapid retreat of Thwaites Glacier in the pre-satellite era. Nature Geoscience.

https://doi.org/10.1038/s41561-022-01019-9

A. P. Lepp *, L. M. Simkins, J. B. Anderson, R. W. Clark, J. S. Wellner, C-D. Hillenbrand, J. A. Smith, A. A. Lehrmann, R. Totten, R. D. Larter, K. A. Hogan, F. O. Nitsche, A. G. C. Graham and L. Wacker. (2022) Sedimentary Signatures of Persistent Subglacial Meltwater Drainage From Thwaites Glacier, Antarctica. Frontiers in Earth Science, Sec. Cryospheric Sciences,doi.org/10.3389/feart.2022.863200.

https://www.frontiersin.org/articles/10.3389/feart.2022.863200/full

Wåhlin, A.K., Graham, A.G.C., Hogan, K.A. , Queste, B.Y., Boehme, L., Larter, R.D. , Pettit, E.C., Wellner, J., Heywood, K.J. (2021) Pathways and modification of warm water flowing beneath Thwaites Ice Shelf, West Antarctica. Science Advances, 7. 10 pp. 2021

https://doi.org/10.1126/sciadv.abd7254

Kelly A. Hogan, Robert D. Larter, Alastair G. C. Graham, Robert Arthern, James D. Kirkham, Rebecca Totten Minzoni, Tom A. Jordan, Rachel Clark, Victoria Fitzgerald, John B. Anderson, Claus-Dieter Hillenbrand, Frank O. Nitsche, Lauren Simkins, James A. Smith, Karsten Gohl, Jan Erik Arndt, Jongkuk Hong, Julia Wellner, Anna Wahlin. (2020) Revealing the former bed of Thwaites Glacier using sea-floor bathymetry. The Cryosphere 14, 2883–2908, 2020.

https://doi.org/10.5194/tc-2020-25

James D. Kirkham, Kelly A. Hogan, Robert D. Larter, Neil S. Arnold, Frank O. Nitsche, Gerhard Kuhn, Karsten Gohl, John B. Anderson, Julian A. Dowdeswell. (2020) Morphometry of bedrock meltwater channels on Antarctic inner continental shelves: Implications for channel development and subglacial hydrology. Geomorphology (in press available 8 Aug 2020).

https://doi.org/10.1016/j.geomorph.2020.107369

James D. Kirkham, Kelly A. Hogan, Robert D. Larter, Neil S. Arnold, Frank O. Nitsche, Nicholas R. Golledge, and Julian A. Dowdeswell. (2019) Past water flow beneath Pine Island and Thwaites glaciers, West Antarctica. The Cryosphere 13(7):1959-1981.

https://www.the-cryosphere-discuss.net/tc-2019-67/

Hillenbrand, C.-D., Smith, J.A., Hodell, D.A., Greaves, M., Poole, C.R., Kender, S., Williams, M., Andersen, T.J., Jernas, P.E., Elderfield, H., Klages, J.P., Roberts, S.J., Gohl, K., Larter, R.D. & Kuhn, G. (2017) West Antarctic Ice Sheet retreat driven by Holocene warm water incursions. Nature, 547: 43-48.

https://www.nature.com/articles/nature22995

RELATED PUBLICATIONS BY THOR TEAM MEMBERS

Herbert, L.C., Lepp, A.P., Munevar Garcia, S., Browning, A., Miller, L.E., Wellner, J., Severmann, S., Hillenbrand, C.-D., Johnson, J.S. & Sherrell, R.M. (2023): Volcanogenic fluxes of iron from the seafloor in the Amundsen Sea, West Antarctica. – Marine Chemistry, 253: 104250.

 https://doi.org/10.1016/j.marchem.2023.104250.

Park, Y.K., Hillenbrand, C.-D., Ehrmann, W., Park H., Wellner, J.S., Horrocks, J.R. & Kim, J. (2024): Elemental composition of smectite minerals in continental rise sediments from the Amundsen Sea, West Antarctica, as a tool to identify detrital input from various sources throughout late Quaternary glacial-interglacial cycles. – Chemical Geology, 657: 122116.

https://doi.org/10.1016/j.chemgeo.2024.122116.

Munevar Garcia, S., Miller, L.E., Falcini, F.A.M. & Stearns, L.A. (2023): Characterizing bed roughness on the Antarctic continental margin. – Journal of Glaciology, 1-12.

https://doi.org/10.1017/jog.2023.88.

Simkins, L.M., Greenwood, S.L., Winsborrow, M.C.M., Bjarnadóttir, L.R. & Lepp, A.P. (2023): Advances in understanding subglacial meltwater drainage from past ice sheets. – Annals of Glaciology, 63 (87-89): 83-87.

https://doi.org/10.1017/aog.2023.16.

Wåhlin, A., Alley, K.E., Begeman, C., Hegrenæs, Ø., Yuan, X., Graham, A.G.C., Hogan, K., Davis, P.E.D., Dotto, T.S., Eayrs, C., Hall, R.A., Holland, D., Kim, T.W., Larter, R.D., Ling, L., Muto, A., Pettit, E.C., Schmidt, B.E., Snow, T., Stedt, F., Washam, P.M., Wahlgren, S., Wild, C., Wellner, J., Zheng, Y. & Heywood, K.J. (2024): Swirls and scoops: new insights into how the ocean melts Antarctica's ice shelves. – Science Advances, 10: eadn9188.

https://doi.org/10.1126/sciadv.adn9188.

Graham A.G.C., Dutrieux, P., Vaughan, D.G., Nitsche, F.O., Gyllencreutz, R., Greenwood, S.L., Larter, R.D., Jenkins, A. (2013). Seabed corrugations beneath an Antarctic ice shelf revealed by autonomous underwater vehicle survey: Origin and implications for the history of Pine Island Glacier. Journal of Geophysical Research: Earth Surface, 118(3), 1356-1366.

https://agupubs.onlinelibrary.wiley.com/doi/10.1002/jgrf.20087

Elaine M.Mawbey, Katharine R.Hendry, Mervyn J.Greaves, Claus-Dieter Hillenbrand, Gerhard Kuhn, Charlotte L.Spencer-Jones, Erin L.McClymont, Kara J. Vadman, Amelia E.Shevenell, Patrycja E.Jernas, James A.Smith (2020) Mg/Ca-Temperature Calibration of Polar Benthic foraminifera species for reconstruction of bottom water temperatures on the Antarctic shelf. Geochimica et Cosmochimica Acta, V. 283, 54-66

https://www.sciencedirect.com/science/article/pii/S001670372030346X?via%3Dihub

Sproson, A.D., Yokoyama, Y., Miyairi, Y., Aze, T. & Rebecca L. Totten (2022) Holocene melting of the West Antarctic Ice Sheet driven by tropical Pacific warming. Nature Communications 13, 2434.

https://doi.org/10.1038/s41467-022-30076-2

Rebecca L. Totten, Adlai Nathanael Reuel Fonseca, Julia Smith Wellner, Yuribia P. Munoz, John B. Anderson, Thomas S. Tobin, Asmara A. Lehrmann (2022) Oceanographic and climatic influences on Trooz Glacier, Antarctica during the Holocene. Quaternary Science Reviews, V. 276, 107279.

https://doi.org/10.1016/j.quascirev.2021.107279

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