January 31 2002 March 7 2002
Figure 6A.4: Break-up of the Larsen B ice shelf. These are images from NASA’s MODIS satellite sensor. Part of the Antarctic Pe-
ninsula is on the left. The image on the left shows the shelf in late summer, with dark bluish melt ponds on the surface. The image
on the right, collected only five weeks later, shows a large part of the ice shelf collapsed, with thousands of sliver icebergs at the
margins and a large blue area of ice fragments.
Images: National Snow and Ice Data Center
The questionable stability of Antarctic ice shelves in a The Larsen B collapse prompted researchers to look at
warming climate was highlighted by the collapse of the the implications of ice-shelf decay for the stability of Ant-
Larsen B Ice Shelf in 2002 off the northern Antarctic Pe- arctica’s inland ice. Glaciers that fed the former ice shelf
ninsula (Figure 6A.4). The significance of this event was have speeded up by factors of two to eight following the
highlighted by records from six marine sediment cores in collapse
13
. In contrast, glaciers further south did not ac-
the vicinity showing that this scale of collapse is unprec- celerate as they are still blocked by an ice shelf. The large
edented since the end of the last ice age. Research implies magnitude of the glacier changes illustrates the impor-
that the long-term thinning of the ice shelf has combined tant influence of ice shelves on ice sheet mass balance.
with the modern half-century-long warming in the Ant-
arctic Peninsula region to cause its disintegration
12
. More- Much further south, in the Amundsen Sea sector of
over, nine other small ice shelves around the Antarctic Pe- West Antarctica, satellite radar measurements show that
ninsula have broken up over the last 100 years. ice shelves have thinned by up to 5.5 meters per year
106 GLOBAL OUTLOOK FOR ICE AND SNOW