Thousands of marks on the Antarctic seafloor, caused by icebergs which broke free from glaciers more than ten thousand years ago, show how part of the Antarctic Ice Sheet retreated rapidly at the end of the last ice age as it balanced precariously on sloping ground and became unstable. Today, as the global climate continues to warm, rapid and sustained retreat may be close to happening again, and could trigger runaway ice retreat into the interior of the continent, which in turn would cause sea levels to rise even faster than currently projected.
Thousands of marks on the Antarctic seafloor, caused by icebergs which broke free from glaciers more than ten thousand years ago, show how part of the Antarctic Ice Sheet retreated rapidly at the end of the last ice age as it balanced precariously on sloping ground and became unstable. Today, as the global climate continues to warm, rapid and sustained retreat may be close to happening again, and could trigger runaway ice retreat into the interior of the continent, which in turn would cause sea levels to rise even faster than currently projected.
Researchers from the University of Cambridge, the British Antarctic Survey and Stockholm University imaged the seafloor of Pine Island Bay, in West Antarctica. They found that, as seas warmed at the end of the last ice age, Pine Island Glacier retreated to a point where its grounding line – the point where it enters the ocean and starts to float – was perched precariously at the end of a slope.
Break up of a floating ‘ice shelf’ in front of the glacier left tall ice ‘cliffs’ at its edge. The height of these cliffs made them unstable, triggering the release of thousands of icebergs into Pine Island Bay, and causing the glacier to retreat rapidly until its grounding line reached a restabilising point in shallower water.
Read more at British Antarctic Survey
Image: Large tabular icebergs grounded on a bank near the northern margin of inner Pine Island Bay. (Photo credit: Robert Larter)
