Tuesday, August 4, 2009

Antarctic Warming: Wilkins Ice Bridge Collapses

In early April 2009 the Wilkins Ice Bridge connecting Latady and Charcot Island on the Antarctic Peninsula collapsed. The disintegration of this ice bridge will allow the further disintegration of the Wilkins ice shelf. A large part of the Wilkins Ice Shelf disintegrated in February 2008.

As this ice is already floating on water, the subsequent melting will not affect sea levels. Neither does the Wilkins Ice Shelf buttress any major glaciers that would increase speed and thus contribute to increased sea levels. However the breakup is symptomatic of increasing warming being felt in the Southern Ocean and particularly the Antarctica Peninsula and West Antarctica.

Ted Scambos of the National Snow and Ice Data Center said that many factors contributed to the collapse of the ice shelf, including brine on the ice, physical stresses on the shelf, and warming temperatures.

Over the previous 50 years, the Antarctic Peninsula has experienced a temperature increase of 0.5 degrees Celsius (0.9 degrees Fahrenheit) per decade, making it one of the fastest warming places on Earth, according to the National Snow and Ice Data Center.

"Everyone knows it has been warming on the Antarctic Peninsula, where there are lots of weather stations collecting data," said Eric Steig, a climate researcher at the University of Washington in Seattle, "Our analysis told us that it is also warming in West Antarctica." Eric Steig used satellite data and statistical analysis to confirm the warming trend as data collection on the ground is restricted to primarily the few ground-based weather stations around the coast of Antarctica.

West Antarctica is particularly vulnerable to climate changes because its ice sheet is grounded below sea level and surrounded by floating ice shelves holding back several glaciers. If the West Antarctic ice sheet completely melted, scientists estimate global sea level would rise by 16 to 20 feet (5 to 6 meters).

The Wilkins Ice Shelf is the tenth major ice shelf to collapse in recent times. The Larsen B ice shelf rapidly and spectacularly collapsed in 2002, allowing the pent up glacier ice to more rapidly discharge.

Sources:
* NASA March 28, 2008 - Disintegration: Antarctic Warming Claims Another Ice Shelf

* NASA December 4, 2008 - New Cracks in the Wilkins Ice Shelf

* NASA April 8, 2009 - Wilkins Ice Bridge Collapse

* NASA January 21, 2009 - Satellites Confirm Half-Century of West Antarctic Warming

* NASA January 23, 2009 - Antarctic Warming Trends

* RealClimate Blog - April 6, 2009 - Wilkins ice shelf collapse

Originally posted on Climate IMC