More Clues as to how Climate Change may Affect Global Sea Levels

A report published today in the journal Science helps to reveal more about the possible effects of climate change on global sea level. According to the 2007 4th Assessment Report issued by the Intergovernmental Panel on Climate Change ice shelf breakup is a major contributor to global sea level rise:

“Taken together, the ice sheets in Greenland and
Antarctica have very likely been contributing to sea
level rise over 1993 to 2003.”  IPCC 4th Assessment Report

• » See also: Greenland Ice Sheet Melting Faster than Ever
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The research undertaken by scientists in the U.S.A. helps to shed light on how ice shelves break up into icebergs. An ice shelf is the part of an ice sheet that lies over the ocean. They are formed as the ice sheet spreads under its own weight. Some shelves can be quite narrow, with others such as the Ross ice shelf in Antarctica extending 800km from the coast and covering an area about 1/2 the size of France.

Ice shelves lose ice, and therefore mass, when icebergs ‘calve’ away from the seaward front of the shelf. The team has identified the rate at which the shelf spreads away from the continent as the primary cause of calving. They also indicate that smaller ice shelves should calve away more slowly than larger shelves.

Computer models which predict how ice shelves will behave as the world warms have until now been restricted in their ability to predict ice shelf calving. Hopefully this new study will allow the models to be able to predict this behaviour with greater accuracy. This will enable scientists to have a more precise idea of how sea level will change as the climate changes.

It is estimated that if all the ice locked up in the Greenland and Antarctica were to melt then global sea level would rise by approximately 60m. Obviously any research that helps improve our understanding of the complex behaviour of these systems will be very valuable in predicting how it may affect the rest of the world. Especially considering that most of the planets population presently lives on or near the coast.

Image credit: kaet44 at Flickr under a Creative Commons license

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