The Amundsen Sea is a key region of Antarctica where ocean, atmosphere, sea ice, and ice sheet interact. For much of Antarctica, the relatively warm water of the open Southern Ocean (a few degrees above freezing) does not reach the Antarctic continental shelf in large volumes under current climate conditions. However, in the Amundsen Sea, warm water penetrates onto the continental shelf and provides heat that can melt the underside of the area’s floating ice shelves, thinning them. Here, we discuss how the ocean’s role in melting has come under increased scrutiny, present 2014 observations from the Amundsen Sea, and discuss their implications, highlighting aspects where understanding is still incomplete.

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, I.A. Renfrew, D.P. Stevens, and B.G.M. Webber. 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.

Arndt, J.E., H.W. Schenke, M. Jakobsson, F.O. Nitsche, G. Buys, B. Goleby, M. Rebesco, F. Bohoyo, J. Hong, J. Black, and others. 2013. The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0—A new bathymetric compilation covering circum-Antarctic waters. Geophysical Research Letters 40(9):3,111–3,117, https://doi.org/10.1002/grl.50413. 
1. 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(12):6,603–6,620, https://doi.org/​10.1002/2013JC008871.
2. Boehme, L., P. Lovell, M. Biuw, and M. Fedak. 2009. Technical note: Animal-borne CTD-satellite relay data loggers for real-time oceanographic data collection. Ocean Science 5(2):685–695, https://doi.org/10.5194/os-5-685-2009.
3. Chavanne, C.P., K.J. Heywood, K.W. Nicholls, and I. Fer. 2010. Observations of the Antarctic Slope Undercurrent in the southeastern Weddell Sea. Geophysical Research Letters 37, L13601, https://doi.org/10.1029/2010GL043603.
4. Church, J.A., P.U. Clark, A. Cazenave, J.M. Gregory, S. Jevrejeva, A. Levermann, M.A. Merrifield, G.A. Milne, R.S. Nerem, P.D. Nunn, and others. 2013. Sea level change. Chapter 13 in Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. T.F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex, and P.M. Midgley, eds, Cambridge University Press, Cambridge, United Kingdom, and New York, NY, USA. 
5. Connolley, W.M. 1997. Variability in annual mean circulation in southern high latitudes. Climate Dynamics 13(10):745–756, https://doi.org/10.1007/s003820050195.
6. Doake, C.S.M., H.F.J. Corr, H. Rott, P. Skvarca, and N.W. Young. 1998. Breakup and conditions for stability of the northern Larsen Ice Shelf, Antarctica. Nature 391:778–780, https://doi.org/10.1038/35832.
7. 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.
8. Elvidge, A.D., I.A. Renfrew, J.C. King, A. Orr, and T.A. Lachlan-Cope. 2016. Foehn warming distributions in non-linear and linear flow regimes: A focus on the Antarctic Peninsula. Quarterly Journal of the Royal Meteorological Society 142:618–631, https://doi.org/10.1002/qj.2489.
9. Fogt, R.L., A.J. Wovrosh, R.A. Langen, and I. Simmonds. 2012. The characteristic variability and connection to the underlying synoptic activity of the Amundsen-Bellingshausen Seas Low. Journal of Geophysical Research 117, D07111, https://doi.org/10.1029/2011JD017337.
10. Fretwell, P., H.D. Pritchard, D.G. Vaughan, J.L. Bamber, N.E. Barrand, R. Bell, C. Bianchi, R.G. Bingham, D.D. Blankenship, G. Casassa, and others. 2013. Bedmap2: Improved ice bed, surface and thickness datasets for Antarctica. The Cryosphere 7:375–393, https://doi.org/10.5194/tc-7-375-2013.
11. Gille, S.T. 2008. Decadal-scale temperature trends in the Southern Hemisphere ocean. Journal of Climate 21:4,749–4,765, https://doi.org/​10.1175/2008JCLI2131.1. 
12. 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.
13. Heuzé, C., K.J. Heywood, D.P. Stevens, and J.K. Ridley. 2013. Southern Ocean bottom water characteristics in CMIP5 models. Geophysical Research Letters 40:1,409–1,414, https://doi.org/10.1002/grl.50287.
14. Hosking, J.S., A. Orr, G.J. Marshall, J. Turner, and T. Phillips. 2013. The influence of the Amundsen-Bellingshausen Seas Low on the climate of West Antarctica and its representation in coupled climate model simulations. Journal of Climate 26(17):6,633–6,648, https://doi.org/10.1175/JCLI-D-12-00813.1.
15. Jacobs, S.S., and C.F. Giulivi. 2010. Large multidecadal salinity trends near the Pacific-Antarctic continental margin. Journal of Climate 23(17):4,508–4,524, https://doi.org/​10.1175/2010JCLI3284.1.
16. Jacobs, S.S., H.H. Hellmer, and A. Jenkins. 1996. Antarctic Ice Sheet melting in the Southeast Pacific. Geophysical Research Letters 23(9):957–960, https://doi.org/10.1029/96GL00723.
17. Jacobs, S.S., H. Hellmer, C. Giulivi, F. Nitsche, B. Huber, and R. Guerrero. 2012. The Amundsen Sea and the Antarctic Ice Sheet. Oceanography 25(3):154–163, https://doi.org/10.5670/oceanog.2012.90. 
18. Jacobs, S.S., C.F. Giulivi, and P.A. Mele. 2002. Freshening of the Ross Sea during the late 20th century. Science 297:386–389, https://doi.org/10.1126/science.1069574.
19. 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.
20. 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.
21. Jenkins, A., and S. Jacobs. 2008. Circulation and melting beneath George VI Ice Shelf, Antarctica. Journal of Geophysical Research 113, C04013, https://doi.org/10.1029/2007JC004449.
22. 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(7):468–472, https://doi.org/10.1038/ngeo890.
23. Jones, R.W., I.A. Renfrew, A. Orr, B.G.M. Webber, D.M. Holland, and M.A. Lazzara. 2016. Evaluation of four global reanalysis products using in situ observations in the Amundsen Sea Embayment, Antarctica. Journal of Geophysical Research 121:6,240–6,257, https://doi.org/​10.1002/2015JD024680.
24. Joughin, I., B.E. Smith, and B. Medley. 2014. Marine ice sheet collapse potentially under way for the Thwaites Glacier Basin, West Antarctica. Science 334:735–738, https://doi.org/10.1126/science.1249055.
25. Keck Institute for Space Studies. 2015. The Sleeping Giant: Measuring Ocean-Ice Interactions in Antarctica. A. Thompson, J. Willis, and A. Payne, study co-leads, California Institute of Technology, Pasadena CA, http://kiss.caltech.edu/new_website/programs/Ocean_Ice_Final_Report.pdf.
26. 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.
27. Nakayama, Y., M. Schroder, 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.
28. Nakayama, Y., R. Timmermann, M. Schröder, and 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.
29. Paolo, F.S., H.A. Fricker, and L. Padman. 2015. Volume loss from Antarctic ice shelves is accelerating. Science 348:327–331, https://doi.org/​10.1126/science.aaa0940.
30. Park, J.W., N. Gourmelen, A. Shepherd, S.W. Kim, D.G. Vaughan, and D.J. Wingham. 2013. Sustained retreat of the Pine Island Glacier. Geophysical Research Letters 40(10):2,137–2,142, https://doi.org/10.1002/grl.50379.
31. Richardson, G., M.R. Wadley, K.J. Heywood, D.P. Stevens, and H.T. Banks. 2005. Short-term climate response to a freshwater pulse in the Southern Ocean. Geophysical Research Letters 32, L03702, https://doi.org/10.1029/2004GL021586.
32. Rignot, E., S.S. Jacobs, J. Mouginot, and B. Scheuchl. 2013. Ice-shelf melting around Antarctica. Science 341:266–270, https://doi.org/10.1126/science.1235798.
33. 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 41:3502–3509, https://doi.org/10.1002/2014GL060140. 
34. Ruddick, B.R. 1983. A practical indicator of the stability of the water column to double-diffusive activity. Deep Sea Research Part A 30:1,105–1,107, https://doi.org/10.1016/0198-0149(83)90063-8. 
35. 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.
36. 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 53:156–162, https://doi.org/10.3189/2012AoG60A073.
37. 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.
38. Shepherd, A., E.R. Ivins, A. Geruo, V.R. Barletta, M.J. Bentley, S. Bettadpur, K.H. Briggs, D.H. Bromwich, R. Forsberg, N. Galin, and others. 2012. A reconciled estimate of ice-sheet mass balance. Science 338:1,183–1,189, https://doi.org/​10.1126/science.1228102.
39. Spence, P., S.M. Griffies, M.H. England, A. McC. Hogg, O.A. Saenko, and N.C. Jouradin. 2014. Rapid subsurface warming and circulation changes of Antarctic coastal waters by poleward shifting winds. Geophysical Research Letters 41:4,601–4,610, https://doi.org/10.1002/2014GL060613.
40. 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(60):19–28, https://doi.org/10.3189/2012AoG60A110.
41. Stewart, A.L., and A.F. Thompson. 2015. Eddy-mediated transport of warm Circumpolar Deep Water across the Antarctic shelf break. Geophysical Research Letters 42:432–440, https://doi.org/10.1002/2014GL062281.
42. St-Laurent, P., J.M. Klinck, and M.S. Dinniman. 2013. On the role of coastal troughs in the circulation of warm circumpolar deep water on Antarctic shelves. Journal of Physical Oceanography 43:51–64, https://doi.org/10.1175/JPO-D-11-0237.1.
43. 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(10):6,718–6,732, https://doi.org/​10.1002/2015JC010709.
44. Thoma, M., A. Jenkins, D. Holland, and S. Jacobs. 2008. Modelling Circumpolar Deep Water intrusions on the Amundsen Sea continental shelf, Antarctica. Geophysical Research Letters 35, L18602, https://doi.org/10.1029/2008GL034939.
45. Thompson, A.F., K.J. Heywood, S, Schmidtko, and A.L. Stewart. 2014. Eddy transport as a key component of the Antarctic overturning circulation. Nature Geoscience 7:879–884, https://doi.org/10.1038/ngeo2289.
46. Thurnherr, A.M., S.S. Jacobs, P. Dutrieux, and C.F. Giulivi. 2014. Export and circulation of ice cavity water in Pine Island Bay, West Antarctica. Journal of Geophysical Research 119:1,754–1,764, https://doi.org/10.1002/2013JC009307. 
47. Turner, J., J.S. Hosking, T.J. Bracegirdle, G.J. Marshall, and T. Phillips. 2015. Recent changes in Antarctic sea ice. Philosophical Transactions of the Royal Society A, https://doi.org/10.1098/rsta.2014.0163.
48. Turner, J., T. Phillips, J.S. Hosking, G.J. Marshall, and A. Orr. 2013. The Amundsen Sea low. International Journal of Climatology 33(7):1,818–1,829, https://doi.org/10.1002/joc.3558.
49. Wåhlin, A.K., R.D. Muench, L. Arneborg, G. Bjork, H.K. Ha, S.H. Lee, and H. Alsen. 2012. Some implications of Ekman layer dynamics for cross-shelf exchange in the Amundsen Sea. Journal of Physical Oceanography 42:1,461–1,474, https://doi.org/10.1175/JPO-D-11-041.1. 
50. 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.
51. 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.
52. 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.
53. Weertman, J. 1974. Stability of the junction of an ice sheet and an ice shelf. Journal of Glaciology 13:3–11.
54. Yager, P.L., R.M. Sherrell, S.E. Stammerjohn, A.-C. Alderkamp, O. Schofield, E.P. Abrahamsen, K.R. Arrigo, S. Bertilsson, D.L. Garay, R. Guerrero, and others. 2012. ASPIRE: The Amundsen Sea Polynya International Research Expedition. Oceanography 25(3):40–53, https://doi.org/​10.5670/oceanog.2012.73.
55. You, Y. 2002. A global ocean climatological atlas of the Turner angle: Implications for double-diffusion and water-mass structure. Deep Sea Research Part I 49:2,075–2,093, https://doi.org/10.1016/S0967-0637(02)00099-7.
56. Zhang, X., A.F. Thompson, M.M. Flexas, F. Roquet, and H. Bornemann. 2016. Circulation and meltwater distribution in the Bellingshausen Sea: From shelf break to coast. Geophysical Research Letters 43:6,402–6,409, https://doi.org/10.1002/2016GL068998.

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.