Slice of ice

Reuters

Two Adelie penguins rest on the shores of Commonwealth Bay in Antarctica.

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Far from New Zealand's Antarctic camp, Scott Base, lost in the vast expanse of the Ross Ice Shelf, lies an ice-covered land mass by the name of Roosevelt Island.

Come early October a Kiwi-led group of scientists will be flown into the bleak wilderness to establish camp and begin to drill 780 metres of ice core to the bedrock as part of an international scientific collaboration.

Trapped inside the ice cores are little air bubbles that record the climatic history of the atmosphere, from when snow packs were compressed to become ice thousands of years ago. Once retrieved, the core samples can be taken to places like the ice core facility at the Geological and Nuclear Sciences (GNS) national isotope centre in Lower Hutt and processed. Scientists are able to determine such variables as temperature change, the chemical makeup of the trapped air and when the snow fell.

Why is this information important? The Ross Ice Shelf is a vast floating mass of ice, approximately the size of Spain, which holds in the West Antarctic Ice Sheet (WAIS). Previous research by New Zealand scientists has found that when the Ross Ice Shelf has disappeared in the past, West Antarctica became unstable and disintegrated.

This can have a serious impact on sea level rise, says Ed Butler, science and information manager for Antarctica New Zealand. If the Ross Ice Shelf ceases to support the glaciers of the ice sheet behind it, the glaciers rush forward into the ocean, and if they melt it can contribute between 5m to 7m of sea-level rise.

It was with this in mind that research was planned to investigate the Ross Ice Shelf as an early warning system and thus the five nations' "Roosevelt Island Climate Evolution" or Rice, project was born.

Dr Nancy Bertler, of the Victoria University Antarctic Research Centre, is heading the project.

It is touted as New Zealand's most ambitious yet within the 19-nation International Trans Antarctic Scientific Expedition programme. Ice coring research has previously been conducted by Dr Bertler and other New Zealand scientists as part of the programme's mission to assess environmental and climate change in and from Antarctica.

Dr Bertler says the Rice project aims to establish the stability of the Ross Ice Shelf and therefore the stability of the ice sheet. They will collaborate with partners from the United States, Denmark, Germany, and Britain to establish the relationship between temperature increase and the retreat of the Ross Ice Shelf during the last glacial maximum 30,000 years ago.

They hope to use this information to predict the future behaviour of the Ross Ice Shelf as both Antarctica and the Southern Ocean continue to warm. This will help to improve the prediction on how much sea-level rise the West Antarctic Ice Sheet will contribute to in the future.

The research will take place over two consecutive summer seasons.

The Roosevelt Island site is located on the northern edge of the Ross Ice Shelf, directly in the path of cyclonic storm activity which means there is the high level of snow precipitation needed for high resolution climate records. It is also an ideal site for research as it is one of only two grounded pinning points of the ice shelf where the biggest changes in ice shelf extent and behaviour are observed.

But because the site is about 750km from Scott Base, they will have to use small fixed-wing planes to get there and this limits the weight of equipment to be carried. Unfortunately, the drilling systems that are traditionally used to drill to such depths are incredibly heavy leaving the scientists a weighty problem.

Enter Alex Pyne, projects manager of the Antarctic Research Centre's science drilling office. Along with his team, he has managed to overcome this barrier thanks to a healthy dose of Kiwi ingenuity.

He made a copy of a light-weight Danish drill rig never used for such a depth range then made modifications to increase its drilling capability. In doing so he created the only operational ice-core drill that is lightweight but capable of drilling down to 1000 metres.

Pyne says they designed quite a lot of their own components to go with the system, using light, high- tech materials because everything will have to be unloaded by hand at the site. He will again be working with Danish colleagues this year when he takes the drill to Greenland for three or four weeks of shallow drilling testing and research.

Danish and American scientists are reportedly interested in adopting the drill modifications and other components that Pyne's team has made. The Americans have a much bigger drill currently operating in Antarctica but also need a more portable system to help obtain ice cores down to about 1000m or 1500m. Pyne says the design is also opening up more scientific collaboration between different countries and, in particular, with European partners as well as the US.

Dr Bertler and her team's work will contribute to the Intergovernmental Panel on Climate Change's predictions on what the planet is going to look like in the next 50-100 years. The panel is the leading body for assessment of climate change, reviewing research from thousands of scientists worldwide and advising the current state and potential consequences of climate change.

Butler says this encapsulates Antarctica New Zealand and the Government's strategy for Antarctic science to have practical benefits for New Zealand. "Not a lot is known about Antarctica and its influence on the global climate, so by doing this sort of work it contributes directly with the science strategy that we're putting together and it has a real outcome that helps New Zealand do its job as an international player in this area."

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