Sensitivity of Pine Island Glacier to observed ocean forcing

Christianson, Knut, Bushuk, Mitchell, Dutrieux, Pierre, Parizek, Byron R., Joughin, Ian R., Alley, Richard B., Shean, David E., Abrahamsen, E. Povl, Anandakrishnan, Sridhar, Heywood, Karen J., Kim, Tae-Wan, Lee, Sang Hoon, Nicholls, Keith, Stanton, Tim, Truffer, Martin, Webber, Benjamin G. M., Jenkins, Adrian, Jacobs, Stan, Bindschadler, Robert and Holland, David M. (2016) Sensitivity of Pine Island Glacier to observed ocean forcing. Geophysical Research Letters, 43 (20). 10,817-10,825. ISSN 0094-8276

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Abstract

We present subannual observations (2009–2014) of a major West Antarctic glacier (Pine Island Glacier) and the neighboring ocean. Ongoing glacier retreat and accelerated ice flow were likely triggered a few decades ago by increased ocean-induced thinning, which may have initiated marine ice sheet instability. Following a subsequent 60% drop in ocean heat content from early 2012 to late 2013, ice flow slowed, but by < 4%, with flow recovering as the ocean warmed to prior temperatures. During this cold-ocean period, the evolving glacier-bed/ice shelf system was also in a geometry favorable to stabilization. However, despite a minor, temporary decrease in ice discharge, the basin-wide thinning signal did not change. Thus, as predicted by theory, once marine ice sheet instability is underway, a single transient high-amplitude ocean cooling has only a relatively minor effect on ice flow. The long-term effects of ocean temperature variability on ice flow, however, are not yet known.

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