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Antarctic knowledge-gap needs to be filled - scientist - 21/03/2002

This week's report of the latest collapse of Larsen B ice shelf in Antarctica is a timely reminder that little is known about the behaviour of the Antarctic ice sheets and ice shelves and their role in global climate change, a New Zealand scientist said today.

Tim Naish, of the GNS Science Limited, said if average global temperatures continue to rise during the next 100 years by as much as 5 degrees, as currently accepted models are predicting, other much larger Antarctic ice shelves will become vulnerable to collapse.

" The Antarctic Peninsula has experienced 2.5 degree increase in temperature over last 50 years, and since the 1990s its ice shelves have progressively deteriorated," Dr Naish said.

" More recently scientists have become concerned with the stability of Antarctica's largest ice shelf, the 536,000 square kilometre Ross Ice Shelf.

" It is becoming especially vulnerable as huge ice streams that feed it from West Antarctica begin to slow or have stopped.

" What we've seen this week is a wake-up call to expect more collapses. It also underlines how little we know about the behaviour of the ice sheets."

The international scientific community was responding to this concern. New Zealand Antarctic climate researchers were taking a leading role in the multinational ANDRILL Project to recover better climate records from the edges of Antarctica.

A major part of the project is to obtain sediment records dating back five million years from under the Ross Ice Shelf.

" This will show us how the ice shelf has behaved in the past so we can better understand its natural instability and predict its future changes due to global warming.

" Even a partial collapse of the Ross Ice Shelf would be globally significant. It would dramatically affect ocean circulation and climate, and could raise sea-level."

Dr Naish is the New Zealand leader of the ANDRILL project.

Preliminary investigations have shown there is likely to be a highly detailed climate record stored in ice under the Ross Ice Shelf.

This summer a team from the Antarctic Research Centre at Victoria University, led by Professor Peter Barrett, will drill holes through the ice shelf and take the first samples from the seafloor in preparation for the major phase of drilling that is expected to recover cores up to 1000m below the seafloor. The $NZ25 million project will drill in four locations in the Southern Curd Sound region.

The project involves scientists from New Zealand, United States, Britain, Italy and Germany. Drilling is scheduled to start in the summer of 2003-4, providing the consortium secures final funding.

Two of the sites will be the deepest drilling projects yet attempted in Antarctica.

Next week Dr Nash is scheduled to travel to Nebraska to attend a meeting of representatives from the five countries to finalise plans for the project.