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NZ scientists lead big climate probe in Antarctica - 06/10/2006

Kiwi ingenuity will be at the forefront when a large multi-national drilling project to investigate Antarctica’s past climate gets underway this month.

The US$30 million ANDRILL (Antarctic geological drilling) programme will use a ‘state of the art’ drill rig to pierce the Ross Ice Shelf and retrieve a 1km-long core of sediment and rock from beneath the seabed.

The aim is to find out more about the behaviour of Antarctic ice sheets during the past five to 10 million years. A key aspect is to find out how quickly ice sheets collapsed in the past when average global temperatures were up to 3 degrees Celsius warmer than at present.

By analysing records preserved in the sediment core of previous times when temperatures were higher than at present, scientists aim to improve predictions about ice sheet behaviour over the next century.

The project will involve 50 scientists and support crew from New Zealand, Italy, Germany, and the United States. It will be the most ambitious seafloor drilling project ever undertaken at the edge of the Antarctic continent.

Located on the Ross Ice Shelf, about 15km west of Scott Base, the drill will pass through 100m of floating ice in McMurdo Sound, then through 900m of water, and into 1000m of sediment and rock. A second drill site, 25km east of Scott Base, is planned for the summer season of 2007-2008.

Porirua company Webster Drilling and Exploration, in collaboration with Victoria University polar drilling specialist Alex Pyne, have developed a drill system to meet the challenging conditions on the Ross Ice Shelf.

The rig has to operate in temperatures as low as 30 degrees below zero and it has to deal with an ice shelf that is continually rising and falling with the tides. To counter this it features a hydraulic platform to accommodate the tidal changes and a hot water system that moves up and down the drill hole to keep it from refreezing.

Chair of the ANDRILL International Science Committee, Gary Wilson of Otago University, said the project had involved five years of intensive planning.

“It’s very exciting to see our drilling programme finally get underway. We are looking forward to seeing what the new drill will uncover,” Dr Wilson said.

Tim Naish

Co-Chief Scientist of the project, Tim Naish of GNS Science, said the project team was hoping the sediment core recovered this summer would provide answers about ice sheet behaviour going back as far as 10 million years.

“Most scientific models predict that the Earth will warm between one and six degrees during the next 100 years. We want to know how this will impact not only on Antarctica, but on the earth’s climate as well,” said Dr Naish, who is also Deputy Director of the Joint Antarctic Research Institute at Victoria University.

“Scientists are increasingly concerned about the stability of the Ross Ice Shelf as global temperatures continue to increase.”

Sections of core recovered by the drill will be taken to the US-run McMurdo Station where a team of scientists from the four participating countries will examine them for initial evidence of Antarctica’s past climate changes. Early in 2007, the cores will be shipped to Florida State University where they will be stored for further detailed research.

Antarctica New Zealand will manage the drilling project, with the drill team being housed at Scott Base. The United States is paying half the cost of the project, New Zealand is contributing 25 percent, Italy 18.5 percent, and Germany 6.5 percent.

http://www.andrill.org

BACKGROUND:

Antarctica acts as the earth’s thermostat, helping to regulate the planet’s climate. Scientists know a lot about how other places respond to global climate change, but little is known about Antarctica. A wealth of information is trapped beneath the ice.

Antarctica is extremely sensitive to climate change. When global temperatures warm past critical thresholds, the ice sheet melts and accelerates the warming effect. When global temperatures cool, the ice sheet expands and accelerates the cooling effect. The cores retrieved by the ANDRILL project will provide a layered sedimentary record that scientists can read like a history book to infer past climate changes.

Seismic surveys in the McMurdo Sound area during the past four years have enabled scientists to determine the best drilling sites. The McMurdo Sound region was selected because it provides access to a full range of geological activity. This includes sedimentary deposits left by glaciers, igneous deposits from volcanic activity, and tectonic shifts that uplifted the nearby Transantarctic Mountains.

At present the knowledge of ice sheet behaviour in Antarctica over the past 20 million years is incomplete. This is a time period that is critical to the understanding of how the earth’s climate system works. Drilling in deeper water than has been attempted in the past will provide a more complete record for scientists to study. Understanding how often, how big, and how fast Antarctica’s past climate changes have been will help scientists understand what is likely to happen in the future.

The Transantarctic Mountains bisect the continent’s ice sheet into two unequal parts. The larger more stable East Antarctic Ice Sheet contains 26 million cubic kilometres of ice. The less stable West Antarctic Ice Sheet contains 3 million cubic kilometres of ice and could contribute 5m to global sea level rise if it melted.