Decadal Ocean Forcing and Antarctic Ice Sheet Response: Lessons from the Amundsen Sea

• Published in: Oceanography
• Main Authors: Adrian Jenkins, Pierre Dutrieux, Stan Jacobs, Eric J. Steig, G. Hilmar Gudmundsson, James Smith, Karen J. Heywood
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Oceanography Society 2016
• Subjects: Antarctic Ice Sheet; Amundsen Sea; ice shelves; ocean warming; Oceanography; GC1-1581; Antarctic; The Antarctic; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves; Sea ice
• Online Access: https://doi.org/10.5670/oceanog.2016.103; https://doaj.org/article/e05c89ccd58444708892ba96514f6e73

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.