With Speed and Violence Fred Pearce - Global Commons Institute

In recent years, Larsen B had been moving forward by about a yard a day.
Despite this constant movement, the ice shelf itself, at more than 650 feet
thick, was a surprisingly permanent structure. After its collapse, study of the
diatoms in the sediment beneath the former shelf suggested that Larsen B
had been there for the entire 12,000 years since the end of the last ice age,
when a single ice sheet covered the whole region.
Larsen B wasn't alone; nor has it been alone in disappearing. In all, more
than 500 square miles of ice shelves have been lost from around the
Antarctic Peninsula in the past half century. The Larsen A ice shelf, the other
side of an ice-covered headland called Seal Nunatak, broke up in a storm in
1995. And before that, the Wordie shelf, on the west side of the peninsula,
disappeared between 1974 and 1996, triggering a dramatic thinning of the
glaciers that fed it. But both were much smaller than Larsen B, and neither
disappeared in the catastrophic manner of Larsen B.
"Really we don't think there is much doubt that the collapse of the Larsen
B shelf was caused by man-made climate change," says John King, chief
climatologist at the British Antarctic Survey (BAS), the inheritor of the great
tradition of explorers such as Robert Scott and Ernest Shackleton. From
their base at Rothera, on Adelaide Island, BAS researchers have mapped in
detail how a pulse of warmer air temperatures has pushed south across the
peninsula over the past fifty years, lengthening the summer melt season,
sending glaciers into retreat, and destabilizing ice shelves as it goes.
Armed with the evidence of Larsen B, glaciologists are reassessing the
stability of dozens of peninsula ice shelves—starting with Larsen C,
immediately to the south, which is thinning and widely expected to be the
next to go. Eventually, they say, the warming will reach the Ronne ice shelf, a