Focusing on two individual icebergs – the larger of which was 21 kilometres wide, had a height above the water level of 40 metres and extended 300 metres below the surface – geochemist Timothy Shaw of the University of South Carolina, USA, and his team found that nutrients released as the masses melted were altering the ecology and chemistry of the sea within a three-kilometre radius. Krill, fish and seabirds are believed to be benefiting from these nutrients, as are phytoplankton – tiny plants that absorb CO2 from the atmosphere as they grow.

Using satellite imagery, the team counted 1,000 icebergs within 11,140 square kilometres of the Weddell Sea in the Southern Ocean. By extrapolating their initial findings, they estimated that biological productivity in the area had increased by 40 per cent.

These findings could have implications for predicting the effects of climate change, as it may mean the oceans are absorbing more CO2 than was previously thought.

August 2007