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Scientists explain why ice shelf shattered in Antarctica


Paulina Keber
Staff Writer

Wednesday, August 14, 2013, 2:55 -

Ever since the summer of 2002, scientists have been wondering what caused a 12,000 year old ice shelf in Antarctica to shatter. This particular ice shelf is named the Larsen B and was responsible for creating about 3000 lakes— which later drained in the space of a week. 

This long ice shelf is a part of the Larsen ice shelf which is located along the east coast of the Antarctic peninsula. It’s broken up into three segments known as Larsen A, Larsen B, and Larsen C. 

The first indication that something was happening to the shelf was when the lakes began draining and disappearing. After this time, the 220 metre thick and 2,700km wide ice shelf began to break apart and disintegrate into small icebergs. 

A new study led by Douglas MacAyeal, a geophysicist at the University of Chicago, sheds light on why this may have happened. According to MacAyeal, the draining of the lakes is what caused the demise of the Larsen B ice shelf. This drainage then impacted the ice shelf as it changed the stress field in nearby areas. The resulting stress then contributed to numerous fractures that formed around the lake that were eventually big enough to shatter the ice shelf. 

It all comes down to the elasticity of the ice. As one lake drains, the weight is taken off of the ice shelf and bounces back up. 

MacAyeal explains that the fractures set off a sort of chain reaction. It was found that when one lake disappeared, fractures appeared under other lakes. And because the lakes were tightly packed together, the close proximity helped to weaken the ice shelf and contribute to fractures in surrounding lakes. So when one lake drained and fractured it caused a chain reaction with other lakes producing more and more fractures. 

Scientists found that each drained lake left a ring fracture that was about 4,000 metres wide. 

The Larsen B ice shelf is not the only one to have disintegrated. Of the three sections that make up the Larsen ice shelf, Larsen A, also disintegrated in January 1995. This leaves Larsen C as the only section left. At this time it appears to be stable, although scientists believe that if the localized warming continues at its current rate, it will also be gone in the foreseeable future.

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