Clue to climate change in Antarctic ice

Clue to climate change in Antarctic ice

New Zealand scientist Mike Williams has received $100,000 funding over two years to study how ice shelves respond to climate change in one of the world’s most pristine and least explored parts of Antarctica – and he won’t even need to get his feet wet.

Dr Williams from the National Institute of Water & Atmospheric Research (NIWA) and Dr Roland Warner from the Australian Antarctic Division and the Antarctic Climate and Ecosystems Cooperative Research Centre will develop computer models to study the formation, transport, and deposition of ice crystals known as ‘frazil ice’ in Lake Vostok and under the Amery Ice Shelf in Antarctica.

Iceberg at barrier transit, Antarctica.

‘Because Lake Vostok is covered by more than 3000 metres of ice, and the Amery Ice Shelf is between 200 metres and 1000 metres thick, computer model simulations are the only way that we can comprehensively study them,’ said Dr Williams. ‘By using a computer model we can also study the lake without risking its unique ecosystem.’

Frazil ice – a slurry of small, thin, disk-shaped crystals, measuring only a few millimetres in diameter – is believed to play an important role in the movement and deposition of ice under ice shelves, and in lakes under the Antarctic Ice Sheet. It has been found suspended in ‘plumes’ next to ice shelves and icebergs, and at the base of the Vostok ice core.

Dr Williams said they would embed a computer model of small-scale ice physics into a larger model that can simulate the water flow within Lake Vostok and in the ocean under the Amery Ice Shelf.

'This will enable us to better understand how ice shelves respond to climate change, including whether or not frazil ice slurries delay the melting of ice shelves caused by a warming Southern Ocean,’ said Dr Williams.

‘Ice shelves effectively isolate the underlying ocean from the atmosphere around much of Antarctica’s coastline, creating a unique environment in the ocean. Lake Vostok, which is the largest of the lakes under the Antarctic Ice Sheet at about 240 km long and 50 km wide, is a completely pristine ecosystem that has never been explored.’

The research is expected to start early next year and is due to finish at the end of 2005. In the longer term it is hoped the results will help scientists understand how ice shelves retreat and why they seem to collapse rapidly at the end of their lives.

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