Scientists drill back in time to find warm Antarctica

RossIce Shelf (Antarctica), Dec 15: From a distance, the ANDRILL operation appears out of nowhere like a mirage: a white-draped tower amid giant blue boxcars laid out on a frozen sea.

But this mammoth venture to drill through ice, ocean and back through time is as real as a science lab and as practical as an oil rig: hard-hatted drillers and scientists work in concert to find clues to a time when Antarctica was warm and wet.

Because the researchers are convinced that a warmer age is in prospect as a result of human-spurred global climate change, they want to know what things were like 10 million years ago, when warmer periods tended to wax and wane on the southern continent.

To do this, they examine core samples taken from the seabed, layer after layer of what looks like solidified gray-green muck. The samples of ancient sediment come out of the rig in cylinders about 30 feet (9 meters) long, contained in steel pipes.

The big drill, which extends about 66 feet (20 meters) above the ice surface, is swathed in a white tent to keep it at temperatures of 50 degrees Fahrenheit (10 degrees Celsius) or higher so that the hydraulics that operate it can continue to work. It runs on JP8 jet fuel.

The scientists start looking at the core samples soon after they are drilled, working out of laboratories fashioned from truck-size blue refrigerator containers.

Some have windows but the sense of being in a meat locker is heightened by the refrigerator-style doors that allow entrance.

Frank Niessen, a geologist with the Alfred Wegener Institute for Polar and Marine Research at Bremerhaven, Germany, studies the core for signs of marine life that indicate an open sea where there is now a 280-foot (85-meter) thick sheet of ice.

Over the last 4 million years or so, Niessen said, there is evidence of some five such warm periods in Antarctica.

Recently, the scientists found a 200-foot (60 meter) length of core that was loaded with microscopic algae called diatoms.

The sediment was so rich in tiny algae skeletons that they dubbed this material diatomite.

At other places, the core was shot through with stones that must have been carried to the sea by glaciers, indicating a colder period, Niessen said.

'A raining of stones'

The transitions between cold and warm times are of particular interest, he said.

Pointing to a detailed graph on his office wall at the drill site, Niessen noted five peaks showing a spike in the density of the core, which he said indicated lots of stones in the sediment.

''To me, it appears a little bit like the raining of stones out of a melting body of ice,'' he said, noting that this is the first sign that it is going to warm up and that the diatoms are about to make a comeback.

''We think this has happened quite a few times in the past,'' and it suggests that at some stage the ice shelf will do the same thing again, Niessen said. ''With global warming, we'll probably go back to these kinds of conditions which would definitely be different than today.'' ''It's very dynamic,'' he said. ''This is the basic message which we are taking home here: We're looking at a very dynamic system.'' ANDRILL stands for Antarctic geological drilling and is a multinational collaboration among Germany, Italy, New Zealand and the United States.

More information is available online at http://www.andrill.org.

Reuters