2012, Oceanography 25(3):202–203, http://dx.doi.org/10.5670/oceanog.2012.95
Adrian Jenkins | British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
Pierre Dutrieux | British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
Stan Jacobs | Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA
Steve McPhail | National Oceanography Centre, Southampton, UK
James Perrett | National Oceanography Centre, Southampton, UK
Andy Webb | National Oceanography Centre, Southampton, UK
Dave White | National Oceanography Centre, Southampton, UK
In recent years, mass loss from the Antarctic Ice Sheet has contributed nearly 0.5 mm yr–1 to global mean sea level rise, about one-sixth of the current rate (Church et al., 2011). Around half of that contribution has come from accelerated draining of outlet glaciers into the southeast Amundsen Sea (Rignot et al., 2008), where the flow speed of Pine Island Glacier (PIG; Figure 1) in particular has increased by over 70%, to around 4 km yr–1, since the first observations in the early 1970s (Rignot, 2008; Joughin et al., 2010). The accelerations have been accompanied by rapid thinning of the glaciers extending inland from the floating ice shelves that form the glacier termini (Shepherd et al., 2002, 2004). One implication of these observed patterns of change is that the mass loss has probably been driven by changes in the rate of submarine melting of the floating ice shelves. The ubiquitous presence of warm Circumpolar Deep Water (CDW) on the Amundsen Sea continental shelf, at temperatures 3–4°C above the pressure freezing point, was first revealed during a 1994 cruise of RVIB Nathaniel B Palmer (Jacobs et al., 1996). Repeat observations at the Pine Island Ice Front made from the Palmer in 2009 showed that submarine melting of PIG had increased by 50% over the intervening 15 years despite a modest rise in the temperature of CDW of only about 0.1°C (Jacobs et al., 2011). While ice front observations were able to document those changes, the reason for the dramatic increase in submarine melting would have remained speculative while the ocean cavity beneath the approximately 65 x 35 km, fast-flowing, central part of the ice shelf remained a black box.
Jenkins, A., P. Dutrieux, S. Jacobs, S. McPhail, J. Perrett, A. Webb, and D. White. 2012. Autonomous underwater vehicle exploration of the ocean cavity beneath an Antarctic ice shelf. Oceanography 25(3):202–203, http://dx.doi.org/10.5670/oceanog.2012.95.
Church, J.A., N.J. White, L.F. Konikow, C.M. Domingues, J.G. Cogley, E. Rignot, J.M. Gregory, M.R. van den Broeke, A.J. Monaghan, and I. Velicogna. 2011. Revisiting the Earth’s sea-level and energy budgets from 1961 to 2008. Geophysical Research Letters 38, L18601, http://dx.doi.org/10.1029/2011GL048794.
Jacobs, S.S., H.H. Hellmer, and A. Jenkins. 1996. Antarctic ice sheet melting in the southeast Pacific. Geophysical Research Letters 23:957–960, http://dx.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, http://dx.doi.org/10.1038/ngeo1188.
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, http://dx.doi.org/10.1038/ngeo890.
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, http://dx.doi.org/10.1029/2010GL044819.
McPhail, S.D., M.E. Furlong, M. Pebody, J.R. Perrett, P. Stevenson, A. Webb, and D. White. 2009. Exploring beneath the PIG Ice Shelf with the Autosub3 AUV. Paper presented at Oceans 09 – Europe, Bremen, Germany, May 11–14, 2009, http://dx.doi.org/10.1109/OCEANSE.2009.5278170.
Rignot, E. 2008. Changes in West Antarctic ice stream dynamics observed with ALOS PALSAR data. Geophysical Research Letters 35, L12505, http://dx.doi.org/10.1029/2008GL033365.
Rignot, E., J.L. Bamber, M.R. van den Broeke, C. Davis, Y. Li, W.J. van de Berg, and E. van Meijgaard. 2008. Recent Antarctic ice mass loss from radar interferometry and regional climate modelling. Nature Geoscience 1:106–110, http://dx.doi.org/10.1038/ngeo102.
Schoof, C. 2007. Ice sheet grounding line dynamics: Steady states, stability, and hysteresis. Journal of Geophysical Research 112, F03S28, http://dx.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, http://dx.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, http://dx.doi.org/10.1029/2004GL021106.