Between January 31st and March 7th,
3,275-square-kilometers of the Larsen B ice shelf disintegrated. While unusual in style, this event follows a pattern of retreat on this eastern Peninsula ice-shelf first identified by glaciologists from the Argentine Antarctic Institute.
The break-up of the floating ice mass, which had survived thousands of years of climate variations, comes at the end of one of the warmest summers on record around the Antarctic Peninsula.
The Larsen Ice Shelf has been under careful observation since 1995, when its northernmost sector collapsed in a similarly dramatic event. At the time, there was no obvious explanation for why an ice shelf should break apart into so many small pieces. The usual pattern is frequent, small iceberg calving events punctuated by infrequent, larger calving events.
Perhaps even more remarkable is the uniqueness of these events within our current interglacial climate. The breakup events have allowed marine geologists access to the sub-ice shelf seafloor, where sediment layers reveal ocean-surface conditions over the millennia. That record indicates that the Larsen A had been in place for about the last 2000 years. The Larsen B is likely to have been significantly older, according to new results from Eugene Domack (Hamilton College, Clinton, NY), Glenn Berger (Desert Research Institute, University of Nevada), and Robert Gilbert (Queen's University, Canada), who sailed into the region this spring aboard the RV Nathanial B. Palmer (the U.S. NSF-supported research icebreaker).
