Concern over ice structures' stability

The calving of a huge iceberg from the Larsen C ice shelf in the western part of Antarctica has triggered questions about its impact on the stability of the polar ice structures, on sea levels and the world climate. The large stretches of ice in both the poles have a major influence on the way life is lived and organised in far away parts of the world. The iceberg which has got separated from the ice shelf is a trillion-tonne entity. It is about 6,000 sq km in area, and about 350 metres thick. The Larsen C ice shelf from which it has broken away is about 50,000 sq km, about the size of Punjab. Ice shelves are gargantuan structures of ice fed by glaciers. Two other ice shelves, Larsen A and Larsen B, have disintegrated in the last two decades. There are fears that the glaciers that feed into the ice shelves would cause a rise in sea levels if the shelves are not there to absorb the water.

The exact impact of the calving of the iceberg and of the melting of ice shelves cannot be predicted. In fact, there may not be enough information about them to make correct assessments because scientific studies of the polar worlds are recent, while the ice is as old as the world. But in the last few decades, there have been intensive studies about the behaviour of ice shelves and icebergs with the help of ships, stations and labs set up tin the polar region and with satellites. The breaking away of the iceberg from Larsen C has been foreseen for some time. Experts are of the view that its impact may not be immediate, but will be felt in some years.

It is thought that the impact will be in the form of a rise in sea level by about 10 cm. This can have serious consequences on life in all parts of the world, especially Asia. The Larsen C event is not directly attributed to climate change but it is felt that there could be linkages that are little understood now. An event like the collapse of Larsen B has not happened in the last 10,000 years. The average rate of ice loss from Antarctica rose from 30 billion tonnes a year in 1992-2002 to 147 billion tonnes a year in 2002-2011. It will not be possible to reverse the process of damage once it sets in and goes past a critical point. That is why its signs and symptoms should be taken seriously.