Antarctic evidence too strong to ignore

More than 50 top international polar scientists will meet at Victoria University of Wellington this week to discuss their cutting-edge climate change research.

The focus will be establishing models that explain how Antarctica’s ice sheets have behaved in Earth’s recent past and explore how they may change in the future.

For several years, scientists from Italy, Germany, New Zealand and the United States have been studying a 1300 metre-long rock core recovered by the multinational ANDRILL (ANtarctic geological DRILLing) programme from beneath the Ross Ice Shelf, in McMurdo Sound, Antarctica.

The core was recovered in 2006 by a team of drillers and engineers from Antarctica New Zealand, who drilled through the ice to a record-setting depth.

The rock core contains valuable evidence of how Antarctica’s ice sheets and climate have changed over time and scientists use this information to learn what is likely to happen to Antarctica’s ice masses in the future and determine how these changes might affect the world’s climate and sea level.

Professor Tim Naish, Director of Victoria’s Antarctic Research Centre, and Professor Ross Powell from Northern Illinois University in the United States are Co-Chief Scientists of the collaborative research project.

Professor Naish says the workshop from 10 to 13 February is the culmination of many years of intensive work and new discoveries by a huge team of scientists, engineers, drillers, and educators.

He says Antarctica’s ice sheets have grown and collapsed at least 40 times over the past five million years.

“Much of our research has focused on the time interval from three to five million years ago. This period in Earth’s history is extremely relevant as it represents a global climate analogue to that projected for our very near future.”

“So far results from our studies on this extraordinary archive of Antarctica’s environmental history are providing critical new insights into past changes in Antarctica’s most vulnerable element: the West Antarctic Ice Sheet. If this ice mass were to melt, global sea-level would rise up to 5 metres – our world would be a very different place.”

Dr Richard Levy of GNS Science, Project Staff Scientist and workshop convenor says the workshop provides a rare opportunity for us to review all aspects of research carried out during the project – work by some of the world’s best polar earth scientists.

“This is a chance to combine our findings and take a huge step forward in our understanding of the Antarctic ice sheet’s response to global climate change.”

Scientists will spend the four days sharing results and debating models and interpretations. A key aim is to establish a strategy to deliver key results to the broader scientific community, general public, and policy makers.

ANDRILL Q & A

What is ANDRILL? The ANtractic geological DRILLing Program is a multi-national collaboration involving Germany, Italy, New Zealand, and the United States. The US30 million project has recovered deep sediment cores from the edge of Antarctica that are vital to answering critical questions about past and future behaviour of Antarctic ice sheets. The results will help to refine computer models used to predict how the Antarctic ice sheets will respond to a warming planet in the future.

Why Antarctica? Antarctica plays a key role in regulating Earth’s climate. Our understanding of the Earth system has been developed mainly with a Northern Hemisphere point of view. However, Antarctica acts a driver of worldwide ocean circulation. Also, Antarctica’s ice volume dictates sea level and climate patterns around the world.

Why drill under the ice shelf? Antarctic ice slowly moves away from the centre of the continent towards the coast. This erodes rocks beneath it, eventually depositing the rocks on the seafloor around Antarctica. Over millions of years, thick layers of sedimentary rocks have accumulated. They hold the story of how the environment has changed and how the ice sheet has behaved. In 2006 the ANDRILL team recovered a 1.3km-long continuous core from under the Ross Ice Shelf, a record for Antarctic drilling. In the 2006-2007 season, drilling took place 15km west of Scott Base.

What happens at the drill site? Two drill teams keep the drill working round the clock and the 8cm-diametre core is brought to the surface in 9m lengths. It is examined immediately by technicians who place reference lines on it so faults, fractures, and other features can be located accurately. After scanning with a high-resolution scanner, scientists study the physical properties of the core. This includes its porosity, density, and electrical resistivity. The core is then cut into 1m lengths and taken to McMurdo Station for further scientific examination.

What happens at McMurdo Station? A large team of scientists including sedimentologists, geochemists, paleontologists, geomagneticists, and petrologists study the core. They each deduce a range of information from the core. A significant part of the core is made up of trillions of marine micro-organisms, with diatoms being the most common. One gram of sediment is likely to contain several hundred million fossilised micro-organisms. From their examinations, scientists are able to reconstruct climate and conditions that prevailed in Antarctica going back about 20 million years.

Where is the core kept? The core is kept in safe long-term storage at Florida State University. It is housed in humidity-controlled conditions at 4degC.

Are there any future geological drilling plans in Antarctica? The ANDRILL drill rig is presently being stored in Antarctica. Scientists involved in this project are planning to drill two deep cores on the Coulman High at the edge of the Ross Ice Shelf, 150km northeast of Scott Base. At this site the drill will pass through the 250m thick ice shelf, and 600m of seawater before drilling about 1000m into the seabed. It will recover core dating from 20 to 35 million years back into Earth’s ‘greenhouse’ period when global temperatures were up to 6degC warmer than today. Scientists are aiming to find out how stable the West Antarctic Ice Shelf is and what West Antarctica was like when the world was significantly warmer than today. It is hoped drilling will start in the 2012/2013 season. It will be preceded by two seasons of detailed field surveys.

ENDS

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