Antarctica has several dozen ice shelves which are huge masses of ice which project from the continent into the southern Ocean. During early 2002 something as amazing as it is worrying happened on the southern tip of the Antarctic continent. More precisely this phenomenon concerns what is left of the 10,000 year old Larsen B ice shelf. In February 2002 NASA scientists first observed the collapse of this particular body of ice. By the end of March 2002 an area of ice measuring over 3000km2 (1,800 square miles), famously quoted as being “at least the size of Rhode Island” simply ceased to exist as a cohesive mass.
The Larsen B ice shelf now exists as an area of slush and icebergs interspersed with pools of melt water that are visible from outer space. As of May 2015 all that is left of the C shaped Shelf is an area which covers 1600 km2. This is between a third and half of the same state of Rhode Island. It is this remaining section of the Larsen B ice shelf that looks set to collapse by 2020.
Research published by NASA in the journal Earth and Planetary Science Letters suggests that a confluence of glacial instability caused by increasing temperatures, faulting and shearing within the ice as well as local topography have allowed the documented collapse of the ice. It’s counterpart the Larsen A ice shelf partially collapsed in 1995 and today both Larsen A and B are losing giga-tonnes of mass on an annual basis.
These findings give climate scientists extra information on how ice shelves move and how they are likely to behave as average temperatures continue to increase. The paper asserts that a series of widening rifts inside what is left of the shelf will precipitate its total collapse by 2020. The need for a global and legally binding framework to reduce and then stop emissions of greenhouse gases is even more apparent
On currents trends of greenhouse gas emissions it is not a question of but when, the Larsen B shelf completely disintegrates. Once Larsen B collapses the glacial system which feeds it is likely to meet the same fate as they will fall directly into the Southern Ocean, thus contributing to increases in global sea levels. This pronouncement is backed by evidence derived from previous studies of the glacier / shelf system which exists in this part of Antarctica. The two principle glaciers the Leppard and Flask are thinning rapidly and the rate of thinning has accelerated since the 2002 collapse.
Other parts of Antarctica are not thinning and some are accumulating snow and ice. However, the Larsen B is not the only collapsing body of ice in Antarctica. The Wilkins Ice Shelf located on the opposite of the peninsula to the Larsen B began to collapse in 2008 and by the summer of 2009 it had entirely collapsed. In total an area of ice approximately 13,500 km2 (5,200 square miles) and up to 300metres thick no longer exists.
In recent decades there have been ten ice shelf collapses and the process shows no sign of deceleration.