Team aims to crack Antarctic ice secrets

The Pine Island Glacier, one of the biggest on Antarctica, may be on the verge of slipping into the sea far faster than anyone previously thought, according to the preliminary results of a survey mission to the White Continent.

The team of scientists from Chile's independent Centre for Scientific Studies and the US space agency (Nasa) has teamed up with the Chilean Navy to make a series of flights over some of Antarctica's most important and unexplored regions.

Their aim has been to create the most detailed maps ever made of the ice surface and the underlying geology, so scientists can accurately measure the impact of climate change.

The mission's head, Chilean theoretical physicist Claudio Teitelboim, described Pine Island as "the Holy Grail" of Antarctic Glaciology.

"It's in the most remote part of the continent, and so we don't know much about it. But it is also where Antarctica is the most unstable, and where any small changes in the Earth's temperature are likely to have a big impact on the ice," he said.

Glaciologist Gino Casassa said recent discoveries had made the study critically important.

"These glaciers are already responding to global warming at a rate that has really surprised the scientific community.

"We've seen them responding over the past decade. But now we can see the disintegration of the ice sheets much faster than we thought. There's evidence that both small and large glaciers could disintegrate even in our own lifetime."

Pine Island is a massive block of ice in the remote and relatively unexplored western corner of Antarctica.

It stretches some 50 kilometres across in places, with ice up to four kilometres deep. It pushes out into the ocean, its mouth protected by the Antarctic sea ice.

The head of Nasa's team, Waleed Abdulat, said one theory was that the sea ice offers a restraint or back pressure, keeping the glaciers in place.

"If you remove that back pressure, the theory suggests that the ice will accelerate much more rapidly, causing a corresponding rise in sea-levels," he said.

In order to carry out the study, Dr Teitelboim invited Nasa to send some of its own scientists and state-of-the-art technology, and convinced the Chilean Navy to dedicate a P-3 Orion aircraft normally used for hunting submarines.

The P-3 Orion is designed to travel long distances, and at relatively low altitude - attributes that make it perfect for a study of this nature.

"This approach is bold," said Dr Teitelboim. "It's not the standard method with lots of logistics and ground support, but it's a hit-and-run mission."

But he pointed out that the collaboration between a civilian research institute and the Chilean navy was also unprecedented in a country still wary of the military institutions that were responsible for brutal repression through the 1970s and 80s.

"It's not only very unusual, but it is also very important to help close that gap and heal the wounds of the past," he said.

For the expedition, the scientists stripped the P-3 of its usual armaments and submarine-detecting equipment, replacing them with five key instruments of their own.

• A laser-imaging system that fires 5,000 pulses of light at the ground every second. The reflections help map the ice surface in stunning detail.
• A ice-penetrating radar to probe the underlying rock-surface, revealing just how deep the ice sheets really are, and what's likely to happen to glaciers should the Earth's temperature rise.
• A pair of high-resolution digital cameras linked together to create stereoscopic images of the ice surface.
• A magnetometer to detect geological activity underneath the rocks, and discover whether underlying volcanic activity might be creating lubricating sheets of water to further destabilise glaciers.
• A Global Positioning System capable of locating the aircraft to within 10 centimetres, and keeping all the other measurements within the same breathtaking degree of accuracy.

The researchers flew a series of low-altitude passes from the Navy's base in over the Antarctic Peninsula, the Patagonian Ice Fields, and the Pine Island Glacier, creating relatively narrow strip-maps or profiles of the ice.

It will take months to process the colossal amount of data into meaningful results, but when it is done, they will provide baseline information for future similar flights.

Even so, the numbers have already indicated that the substrata beneath Pine Island Glacier makes it inherently much more unstable than was previously thought.

"These flights have been incredibly successful," said Claudio Teitelboim. "At every step of the way, the collaboration has worked perfectly, the technology worked perfectly, and even the weather couldn't have been better.

"But the bad news is that it looks as though the rock surface makes Pine Island Glacier very unstable indeed.

"We'll have to do a lot more work to confirm the results, but they don't look very positive."