Mass loss from the Antarctic Ice Sheet is driven by changes at the marine margins. In the Amundsen Sea, thinning of the ice shelves has allowed the outlet glaciers to accelerate and thin, resulting in inland migration of their grounding lines. The ultimate driver is often assumed to be ocean warming, but the recent record of ocean temperature is dominated by decadal variability rather than a trend. The distribution of water masses on the Amundsen Sea continental shelf is particularly sensitive to atmospheric forcing, while the regional atmospheric circulation is highly variable, at least in part because of the impact of tropical variability. Changes in atmospheric circulation force changes in ice shelf melting, which drive step-wise movement of the grounding line between localized high points on the bed. When the grounding line is located on a high point, outlet glacier flow is sensitive to atmosphere-ocean variability, but once retreat or advance to the next high point has been triggered, ocean circulation and melt rate changes associated with the evolution in geometry of the sub-ice-shelf cavity dominate, and the sensitivity to atmospheric forcing is greatly reduced.
Jenkins, A., P. Dutrieux, S. Jacobs, E.J. Steig, G.H. Gudmundsson, J. Smith, and K.J. Heywood. 2016. Decadal ocean forcing and Antarctic ice sheet response: Lessons from the Amundsen Sea. Oceanography 29(4):106–117, https://doi.org/10.5670/oceanog.2016.103.
Assmann, K.M., A. Jenkins, D.R. Shoosmith, D.P. Walker, S.S. Jacobs, and K.W. Nicholls. 2013. Variability of Circumpolar Deep Water transport onto the Amundsen Sea continental shelf through a shelf break trough. Journal of Geophysical Research 118:6,603–6,620, https://doi.org/10.1002/2013JC008871.
Bracegirdle, T. 2013. Climatology and recent increase in westerly winds over the Amundsen Sea derived from six reanalyses. International Journal of Climatology 33:843–851, https://doi.org/10.1002/joc.3473.
Christianson, K., M. Bushuk, P. Dutrieux, B.R. Parizek, I.R. Joughin, R.B. Alley, D.E. Shean, E.P. Abrahamsen, S. Anandakrishnan, K.J. Heywood, and others. 2016. Sensitivity of Pine Island Glacier to observed ocean forcing. Geophysical Research Letters 43:10,817-10,825, https://doi.org/10.1002/2016GL070500.
Corr, H.F.J., C.S.M. Doake, A. Jenkins, and D.G. Vaughan. 2001. Investigations of an “ice plain” in the mouth of Pine Island Glacier, Antarctica. Journal of Glaciology 47:51–57, https://doi.org/10.3189/172756501781832395.
De Rydt, J., and G.H. Gudmundsson. 2016. Coupled ice shelf-ocean modeling and complex grounding line retreat from a seabed ridge. Journal of Geophysical Research 121:865–880, https://doi.org/10.1002/2015JF003791.
De Rydt, J., P.R. Holland, P. Dutrieux, and A. Jenkins. 2014. Geometric and oceanographic controls on melting beneath Pine Island Glacier. Journal of Geophysical Research 119:2,420–2,438, https://doi.org/10.1002/2013JC009513.
Ding, Q., E.J. Steig, D.S. Battisti and M. Kuttel. 2011. Winter warming in West Antarctica caused by central Pacific warming. Nature Geoscience 4:398–403, https://doi.org/10.1038/ngeo1129.
Dutrieux, P., J. De Rydt, A. Jenkins, P.R. Holland, H.K. Ha, S.H. Lee, E.J. Steig, Q. Ding, E.P. Abrahamsen, and M. Schröder. 2014. Strong sensitivity of Pine Island Ice-Shelf melting to climatic variability. Science 343:174–178, https://doi.org/10.1126/science.1244341.
Goldberg, D., D.M. Holland, and C. Schoof. 2009. Grounding line movement and ice shelf buttressing in marine ice sheets. Journal of Geophysical Research 114, F04026, https://doi.org/10.1029/2008JF001227.
Gudmundsson, G.H. 2013. Ice-shelf buttressing and the stability of marine ice sheets. The Cryosphere 7:647–655, https://doi.org/10.5194/tc-7-647-2013.
Ha, H.K., A.K. Wåhlin, T.W. Kim, S.H. Lee, J.H. Lee, H.J. Lee, C.S. Hong, L. Arneborg, G. Björk, and O. Kalén. 2014. Circulation and modification of warm deep water on the central Amundsen shelf. Journal of Physical Oceanography 44:1,493–1,501, https://doi.org/10.1175/JPO-D-13-0240.1.
Hattermann, T., O.A. Nøst, J.M. Lilly, and L.H. Smedsrud. 2012. Two years of oceanic observations below the Fimbul Ice Shelf, Antarctica. Geophysical Research Letters 39, L12605, https://doi.org/10.1029/2012GL051012.
Heywood, K.J., L.C. Biddle, L. Boehme, P. Dutrieux, M. Fedak, A. Jenkins, R.W. Jones, J. Kaiser, H. Mallett, A.C. Naveira Garabato, and others. 2016. Between the devil and the deep blue sea: The role of the Amundsen Sea continental shelf in exchanges between ocean and ice shelves. Oceanography 29(4):118–129, https://doi.org/10.5670/oceanog.2016.104.
Heywood, K.J., R.A. Locarnini, R.D. Frew, P.F. Dennis, and B.A. King. 1998. Transport and water masses of the Antarctic Slope Front system in the eastern Weddell Sea. Pp. 203–214 in Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin. Antarctic Research Series, vol. 75, S.S. Jacobs and R.F. Weiss, eds, American Geophysical Union, Washington, DC.
Hillenbrand, C.-D., G. Kuhn, J.A. Smith, K. Gohl, A.G.C. Graham, R.D. Larter, J.P. Klages, R. Downey, S.G. Moreton, M. Forwick, and others. 2013. Grounding-line retreat of the West Antarctic Ice Sheet from inner Pine Island Bay. Geology 4:35–38, https://doi.org/10.1130/G33469.1.
Hughes, T.J. 1981. The weak underbelly of the West Antarctic ice sheet. Journal of Glaciology 27:518–525.
Jacobs, S.S., H.H. Hellmer, C.S.M. Doake, A. Jenkins, and R.M. Frolich. 1992. Melting of ice shelves and the mass balance of Antarctica. Journal of Glaciology 38:375–387.
Jacobs, S.S., H.H. Hellmer, and A. Jenkins. 1996. Antarctic ice sheet melting in the southeast Pacific. Geophysical Research Letters 23:957–960, https://doi.org/10.1029/96GL00723.
Jacobs, S.S., A. Jenkins, C.F. Giulivi, and P. Dutrieux. 2011. Stronger ocean circulation and increased melting under Pine Island Glacier ice shelf. Nature Geoscience 4:519–523, https://doi.org/10.1038/ngeo1188.
Jacobs, S., A. Jenkins, H. Hellmer, C. Giulivi, F. Nitsche, B. Huber, and R. Guerrero. 2012. The Amundsen Sea and the Antarctic Ice Sheet. Oceanography 25:154–163, https://doi.org/10.5670/oceanog.2012.90.
Jenkins, A., P. Dutrieux, S.S. Jacobs, S.D. McPhail, J.R. Perrett, A.T. Webb, and D. White. 2010. Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat. Nature Geoscience 3:468–472, https://doi.org/10.1038/ngeo890.
Johnson, J.S., M.J. Bentley, J.A. Smith, R.C. Finkel, D.H. Rood, K. Gohl, G. Balco, R.D. Larter, and J.M. Schaefer. 2014. Rapid thinning of Pine Island Glacier in the early Holocene. Science 343:999–1,001, https://doi.org/10.1126/science.1247385.
Joughin, I., B.E. Smith, and D.M. Holland. 2010. Sensitivity of 21st century sea level to ocean-induced thinning of Pine Island Glacier, Antarctica. Geophysical Research Letters 37, L20502, https://doi.org/10.1029/2010GL044819.
Joughin, I., B.E. Smith, and B. Medley. 2014. Marine ice sheet collapse potentially under way for the Thwaites Glacier basin, West Antarctica. Science 344:735–738, https://doi.org/10.1126/science.1249055.
Kalén, O., K.M. Assmann, A.K. Wåhlin, H.K. Ha, T.W. Kim, and S.H. Lee. 2016. Is the oceanic heat flux on the central Amundsen Sea shelf caused by barotropic or baroclinic currents? Deep Sea Research Part II 123:7–15, https://doi.org/10.1016/j.dsr2.2015.07.014.
Kim, C.S., T.W. Kim, K.H. Cho, H.K. Ha, S.H. Lee, H.C. Kim, and J.H. Lee. 2016. Variability of the Antarctic Coastal Current in the Amundsen Sea. Estuarine, Coastal and Shelf Science 181:123–133, https://doi.org/10.1016/j.ecss.2016.08.004.
Martinson, D.G., and D.C. McKee. 2012. Transport of warm Upper Circumpolar Deep Water onto the western Antarctic Peninsula continental shelf. Ocean Science 8:433–442, https://doi.org/10.5194/os-8-433-2012.
McMillan, M., A. Shepherd, A. Sundal, K. Briggs, A. Muir, A. Ridout, A. Hogg, and D. Wingham. 2014. Increased ice losses from Antarctica detected by CryoSat-2. Geophysical Research Letters 41:3,899–3,905, https://doi.org/10.1002/2014GL060111.
Morlighem, M., J. Bondzio, H. Seroussi, E. Rignot, E. Larour, A. Humbert, and S. Rebuffi. 2016. Modeling of Store Gletscher’s calving dynamics, West Greenland, in response to ocean thermal forcing. Geophysical Research Letters 43:2,659–2,666, https://doi.org/10.1002/2016GL067695.
Mouginot, J., E. Rignot, and B. Scheuchl. 2014. Sustained increase in ice discharge from the Amundsen Sea Embayment, West Antarctica, from 1973 to 2013. Geophysical Research Letters 41:1,576–1,584, https://doi.org/10.1002/2013GL059069.
Nakayama, Y., M. Schröder, and H.H. Hellmer. 2013. From Circumpolar Deep Water to the glacial meltwater plume on the eastern Amundsen Shelf. Deep Sea Research Part I 77:50–62, https://doi.org/10.1016/j.dsr.2013.04.001.
Nakayama, Y., R. Timmermann, M. Schröder, and H.H. Hellmer. 2014. On the difficulty of modeling Circumpolar Deep Water intrusions onto the Amundsen Sea continental shelf. Ocean Modelling 84:26–34, https://doi.org/10.1016/j.ocemod.2014.09.007.
Nøst, O.A., M. Biuw, V. Tverberg, C. Lydersen, T. Hattermann, Q. Zhou, L.H. Smedsrud, and K.M. Kovacs. 2011. Eddy overturning of the Antarctic Slope Front controls glacial melting in the eastern Weddell Sea. Journal of Geophysical Research 116, C11014, https://doi.org/10.1029/2011JC006965.
Orsi, A.H., and T. Whitworth III. 2005. Hydrographic Atlas of the World Ocean Circulation Experiment (WOCE): Volume 1. Southern Ocean. M. Sparrow, P. Chapman, and J. Gould, eds, International WOCE Project Office, Southampton, UK.
Park, J.W., N. Gourmelen, A. Shepherd, S.W. Kim, A. Vaughan, and D.G. Wingham. 2013. Sustained retreat of the Pine Island Glacier. Geophysical Research Letters 40:2,137–2,142, https://doi.org/10.1002/grl.50379.
Petty, A.A., D.L. Feltham, and P.R. Holland. 2013. Impact of atmospheric forcing on Antarctic continental shelf water masses. Journal of Physical Oceanography 43:920–940, https://doi.org/10.1175/JPO-D-12-0172.1.
Rignot, E.J. 1998. Fast recession of a West Antarctic glacier. Science 281:549–551, https://doi.org/10.1126/science.281.5376.549.
Rignot, E. 2008. Changes in West Antarctic ice stream dynamics observed with ALOS PALSAR data. Geophysical Research Letters 35, L12505, https://doi.org/10.1029/2008GL033365.
Rignot, E., S. Jacobs, J. Mouginot, and B. Scheuchl. 2013. Ice-shelf melting around Antarctica. Science 341:266–270, https://doi.org/10.1126/science.1235798.
Rignot, E., J. Mouginot, M. Morlighem, H. Seroussi, and B. Scheuchl. 2014. Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011. Geophysical Research Letters 41:3,502–3,509, https://doi.org/10.1002/2014GL060140.
Schmidtko, S., K.J. Heywood, A.F. Thompson, and S. Aoki. 2014. Multidecadal warming of Antarctic waters. Science 346:1,227–1,231, https://doi.org/10.1126/science.1256117.
Schneider, D.P., and E.J. Steig. 2008. Ice cores record significant 1940s Antarctic warmth related to tropical climate variability. Proceedings of the National Academy of Sciences of the United States of America 105:12,154–12,158, https://doi.org/10.1073/pnas.0803627105.
Schodlok, M.P., D. Menemenlis, E. Rignot, and M. Studinger. 2012. Sensitivity of the ice-shelf/ocean system to the sub-ice-shelf cavity shape measured by NASA IceBridge in Pine Island Glacier, West Antarctica. Annals of Glaciology 53(60):156–162, https://doi.org/10.3189/2012AoG60A073.
Schoof, C. 2007. Ice sheet grounding line dynamics: Steady states, stability, and hysteresis. Journal of Geophysical Research 112, F03S28, https://doi.org/10.1029/2006JF000664.
Shepherd, A., D.J. Wingham, and J.A.D. Mansley. 2002. Inland thinning of the Amundsen Sea sector, West Antarctica. Geophysical Research Letters 29, 1364, https://doi.org/10.1029/2001GL014183.
Shepherd, A., D. Wingham, and E. Rignot. 2004. Warm ocean is eroding West Antarctic ice sheet. Geophysical Research Letters 31, L23402, https://doi.org/10.1029/2004GL021106.
Smedsrud, L.H., A. Jenkins, D.M. Holland, and O.A. Nøst. 2006. Modeling ocean processes below Fimbulisen, Antarctica. Journal of Geophysical Research 111, C01007, https://doi.org/10.1029/2005JC002915.
Smith, J.A., T.J. Andersen, M. Shortt, A.M Gaffney, M. Truffer, T.P. Stanton, R. Bindschadler, P. Dutrieux, A. Jenkins, C.-D. Hillenbrand, and others. 2016. Sub-ice-shelf sediments record twentieth-century retreat of Pine Island Glacier. Nature, https://doi.org/10.1038/nature20136.
Smith, J.A., C.-D. Hillenbrand, G. Kuhn, A.G.C. Graham, R.D. Larter, J.-P. Johann, W. Ehrmann, S.G. Moreton, and T. Williams. 2014. New constraints on the timing of West Antarctic Ice Sheet retreat in the eastern Amundsen Sea since the Last Glacial Maximum. Global and Planetary Change 122:224–237, https://doi.org/10.1016/j.gloplacha.2014.07.015.
Steig, E.J., Q. Ding, D.S. Battisti, and A. Jenkins. 2012. Tropical forcing of Circumpolar Deep Water inflow and outlet glacier thinning in the Amundsen Sea Embayment, West Antarctica. Annals of Glaciology 53:19–28, https://doi.org/10.3189/2012AoG60A110.
Steig, E.J., Q. Ding, J.W.C. White, M. Kuttel, S.B. Rupper, T.A. Neumann, P.D. Neff, A.J.E. Gallant, P.A. Mayewski, K.C. Taylor, and others. 2013. Recent climate and ice-sheet changes in West Antarctica compared with the past 2,000 years. Nature Geoscience 6:372–375, https://doi.org/10.1038/ngeo1778.
St-Laurent, P., J.M. Klinck, and M.S. Dinniman. 2015. Impact of local winter cooling on the melt of Pine Island Glacier, Antarctica. Journal of Geophysical Research 120:6,718–6,732, https://doi.org/10.1002/2015JC010709.
Talbot, M.H. 1988. Oceanic environment of George VI Ice Shelf, Antarctic Peninsula. Annals of Glaciology 11:161–164.
Thoma, M., A. Jenkins, D. Holland, and S. Jacobs. 2008. Modeling Circumpolar Deep Water intrusions on the Amundsen Sea continental shelf, Antarctica. Geophysical Research Letters 35, L18602, https://doi.org/10.1029/2008GL034939.
Thomas, R.H., T.J.O. Sanderson, and K.E. Rose. 1979. Effect of climatic warming on the West Antarctic ice sheet. Nature 277:355–358, https://doi.org/10.1038/277355a0.
Timmermann, R., A. Le Brocq, T. Deen, E. Domack, P. Dutrieux, B. Galton-Fenzi, H. Hellmer, A. Humbert, D. Jansen, A. Jenkins, and others. 2010. A consistent data set of Antarctic ice sheet topography, cavity geometry, and global bathymetry. Earth System Science Data 2:261–273, https://doi.org/10.5194/essd-2-261-2010.
Vaughan, D.G., A.M. Smith, H.F.J. Corr, A. Jenkins, C.R. Bentley, M.D. Stenoien, S.S. Jacobs, T.B. Kellogg, E. Rignot, and B.K. Lucchitta. 2001. A review of Pine Island Glacier, West Antarctica: Hypotheses of instability vs. observations of change. Pp. 237–256 in The West Antarctic Ice Sheet: Behavior and Environment. Antarctic Research Series, vol. 77, R. Alley and R. Bindschadler, eds, American Geophysical Union, Washington, DC.
Wåhlin, A.K., O. Kalén, L. Arneborg, G. Björk, G.K. Carvajal, H.K. Ha, T.W. Kim, S.H. Lee, J.H. Lee, and C. Stranne. 2013. Variability of warm deep water inflow in a submarine trough on the Amundsen Sea shelf. Journal of Physical Oceanography 43:2,054–2,070, https://doi.org/10.1175/JPO-D-12-0157.1.
Wåhlin, A.K., X. Yuan, G. Björk, and C. Nohr. 2010. Inflow of Warm Circumpolar Deep Water in the Central Amundsen Shelf. Journal of Physical Oceanography 40:1,427–1,434, https://doi.org/10.1175/2010JPO4431.1.
Walker, D.P., M.A. Brandon, A. Jenkins, J.T. Allen, J.A. Dowdeswell, and J. Evans. 2007. Oceanic heat transport onto the Amundsen Sea shelf through a submarine glacial trough. Geophysical Research Letters 34, L02602, https://doi.org/10.1029/2006GL028154.
Walker, D.P., A. Jenkins, K.M. Assmann, D.R. Shoosmith, and M.A. Brandon. 2013. Oceanographic observations at the shelf break of the Amundsen Sea, Antarctica. Journal of Geophysical Research 118:2,906–2,918, https://doi.org/10.1002/jgrc.20212.
Weertman, J. 1974. Stability of the junction of an ice sheet and an ice shelf. Journal of Glaciology 13:3–13.
Whitworth, T. III, A.H. Orsi, S.-J. Kim, W.D. Nowlin Jr., and R.A. Locarnini. 1998. Water masses and mixing near the Antarctic Slope Front. Pp. 1–27 in Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin. Antarctic Research Series, vol. 75, S.S. Jacobs and R.F. Weiss, eds, American Geophysical Union, Washington, DC.
Wingham, D.J., D.W. Wallis, and A. Shepherd. 2009. Spatial and temporal evolution of Pine Island Glacier thinning, 1995–2006. Geophysical Research Letters 36, L17501, https://doi.org/10.1029/2009GL039126.
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