Friday, February 26, 2010

Vast iceberg 'may disrupt ocean currents'

A vast iceberg snapped from the Mertz Glacier Tongue which broke off the Antarctic continent this month could disrupt the world's ocean currents and weather patterns, scientists warn.Australian researchers say the iceberg - the size of Luxembourg - could block an area that produces a quarter of the world's dense and very cold seawater. They say a slowdown in the production of this water could result in colder winters in the north Atlantic. The iceberg is currently floating south of Australia. Dr Neal Young, a glaciologist at the Antarctic Climate and Ecosystems Research Centre in Tasmania, told the BBC that any disruption to the production of the super cold water - known as bottom water - in the region would affect ocean currents, and consequently weather patterns, for years to come. "This area accounts for about 25% of the production of bottom water in Antarctica, and therefore it will reduce the overturning circulation rate," he said. "You won't see it immediately, but it has downstream effects. And it will also have implications for penguins and other wildlife in the region that normally use this area for feeding." The iceberg is sitting in an area of open water surrounded by sea-ice, known as a polynya. Bottom water produced by polynyas sinks to the bottom of the sea and drives the conveyor-belt like ocean circulation around the globe. Benoit Legresy, a French glaciologist, said the iceberg broke from the Mertz Glacier Tongue, a 160km spit of floating ice protruding from East Antarctica south of Melbourne. It was dislodged by another, older, iceberg known as B9B which split off in 1987. "The ice tongue was almost broken already. It was hanging like a loose tooth," Mr Legresy said. "If they [the icebergs] stay in this area - which is likely - they could block the production of this dense water, essentially putting a lid on the polynya," he added.

No comments: