The History and Geography of the Larsen Ice Shelf:

The Larsen ice shelf is one of the northernmost ice shelves in all of Antarctica, located between 60-62° W longitude and 65-66° S latitude on the eastern coast of the Antarctic Peninsula. The shelf is divided into four parts lettered 'A' through 'D:" Larsen-A is the northernmost section stuck between Robertson Island and the Sobral Peninsula while Larsen B is situated between Robertson Island and the Jason Peninsula (7). The Larsen-B ice shelf is fed by the Crane Glacier and the Hektoria-Green-Evans glacier system (1), and sediment samples taken near Larsen-B indicate that the shelf has been present for at least 12,000 years. However, since the 1940's there has been a gradual 2.5° C increase in temperatures recorded around the Antarctic Peninsula, resulting in a longer summer melting season on top of the Larsen ice shelf by about thirty days (from 50 to about 80 days). This has resulted in the creation of melt water ponds on top of the ice shelf, some up to a kilometer wide (4). Paralleling this increase in melting period has been a 20% decline in sea ice extents surrounding the Larsen ice shelf since 1978 (7), which corroborate the temperature changes during winter months.

Breakup Incidents Before 2002:

The outer bounds of the Larsen ice shelf were either expanding or at equilibrium until 1975, when drastic retreats in Larsen-A began to be observed. Towards the end of January 1995, a storm battering the tip of the Antarctic Peninsula destroyed around 2000km² of the Larsen-A ice shelf and knocked a 1700km² iceberg off of the Larsen-B ice shelf. The destruction of the A shelf paved the way for further retreats in the B shelf, such as a 1024km² retreat in November of 1998 (7). By the year 2000, 4016km² of area had already been lost from Larsen-B.

The 2002 Larsen-B Breakup :

Beginning January 31st, 2002 during the hottest summer ever recorded for the area the interior of the half-moon bay that was Larsen-B crumbled, destroying 3250km2 of ice shelf (4). Satellite images taken by NASA reveal the extent of the collapse. The blue areas on the surface of the ice before it breaks up are melt water ponds that are large enough to be seen from space. As the collapse continues, blue glacial ice becomes exposed as the white, top layers of snow and firn crumble sideways revealing the ancient glacial ice underneath. By March 5th the disintegration was complete, with only a sea of icebergs remaining.

Time lapse animation of the Larsen-B collapse. (8)