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  BBC Online 19 Apr 06
Secret rivers found in Antarctic
By Helen Briggs BBC News science reporter

PlanetArtk 20 Apr 06
Scientists Find Rivers Under Antarctic Ice

LONDON - Rivers as big as the Thames in England that may connect sub-glacial lakes have been found deep under the Antarctic ice, scientists said on Wednesday.

British researchers who discovered the plumbing system that moves water hundreds of miles said it challenges the notion that the lakes under the Antarctic ice evolved independently and could support ancient life.

"Previously, it was thought water moves underneath the ice by very slow seepage," said Professor Duncan Wingham of University College London (UCL) who headed the research team. "But this new data shows that, every so often, the lakes beneath the ice pop off like champagne corks, releasing floods that travel very long distances."

Scientists had plans to drill through the ice to take samples from the lakes but were worried about contaminating them with new microbes.

"We had thought of these lakes as isolated biological laboratories. Now we are going to have to think again," Wingham added in a statement.

The research, which is reported in the journal Nature, also means that water from the Antarctic lakes, which were first discovered in the 1960s, could have flowed into the ocean in the past and that it could happen again.

About 150 sub glacial lakes have been discovered in Antarctica but researchers believe there could be thousands. Lake Vostok, at 15-20 million years old, is thought to be the most ancient.

Scientists from UCL and the Natural Environment Research Council Centre for Polar Observation and Modelling found the rivers by examining changes in measurements taken by the European Space Agency ERS-2 satellite of a region in East Antarctica known as the Dome Concordia. They suspect the changes in the ice sheet show a flow of water from one sub-glacial lake to others.

"The lakes are like a set of beads on a string, where the lakes are the beads connected by a string or river of water," said Wingham. The scientists believe when the pressure in one of the lakes increases, a flood fills the next bead down the string. But they do not know whether the flow of water which melts ice causes a chain reaction down the string.

BBC Online 19 Apr 06
Secret rivers found in Antarctic
By Helen Briggs BBC News science reporter

Antarctica's buried lakes are connected by a network of rivers moving water far beneath the surface, say UK scientists. It was thought the sub-glacial lakes had been completely sealed for millions of years, enabling unique species to evolve in them.

Writing in the journal Nature, experts say international plans to drill into the lakes may now have to be reviewed. Any attempts to drill into one body of water risks contaminating others.

"What this paper shows is that not only could you contaminate a lake, you could contaminate the whole drainage system," lead author Duncan Wingham, of University College London, told the BBC News website.

Time capsules

The sub-glacial lakes of Antarctica are regarded as "time capsules" of the period when the continent began to freeze over. Scientists believe any life they contain might shed light on extreme environments on other worlds, such as the ice-bound ocean on Jupiter's moon Europa.

The presence of the drainage system may change current thinking on the chances of finding microbial life that has evolved "independently". "The notion that these things have been sitting in the lakes evolving for millions of years probably won't wash," said Professor Wingham. "I think the idea that they have an isolated biological environment where things have gone their own way will have to be re-examined."

Professor Martin Siegert, of the University of Bristol, a co-author of the Nature study, said there would still be a very interesting microbiological story to uncover. "We have always thought of sub-glacial lakes as being distinct bodies isolated from each other," he said. "For at least some of these lakes, that won't be true but they will still be isolated from the atmosphere."

It was once thought the Antarctic continent was too cold for water to exist in liquid form beneath its frozen wastes.

But since the 1960s, satellites and aircraft with powerful radar devices have discovered more and more lakes buried kilometres beneath the thick ice sheet. More than 150 have been detected so far, but they are expected to run into thousands.

The largest underground body of water in Antarctica is known as Lake Vostok, which is 250km (155 miles) long, 40km (25 miles) wide and 400m (1,300ft) deep.

The US space agency (Nasa) and the Russian academy of sciences are planning to break through the ice to sample the water for life. There are also proposals to explore and sample Lake Ellsworth in west Antarctica by a team involving 14 UK universities and research institutions, plus scientists from Chile, the US, Sweden, Belgium, Germany and New Zealand.

Satellite data

The latest research was carried out by scientists at the Natural Environment Research Council (Nerc) Centre for Polar Observation and Modelling (CPOM) at UCL, the University of Bristol and University of Cambridge. They took ultra-precise measurements of a region in East Antarctica - home to some of the oldest, thickest ice on the continent - using radars on the European Space Agency's ERS-2 satellite.

The satellite found synchronous changes in the surface height at several locations hundreds of kilometres apart. "To find a whole section - 30km (18 miles) by 10km (6 miles) - had dropped vertically was a great surprise," Professor Wingham explained. "We then found another similar event 300km (186 miles) away, but that bit had increased instead of decreasing. "We were then left with the problem of explaining what was going on. Movement of water was the only mechanism conceivable."

Catastrophic flood

The scientists believe that every so often there are large flows of water from one lake to another along rivers the size of the Thames. Most of the time there is very little discharge, but if a lake over pressurises, a flood occurs that forces the water along the river to the next lake.

"You could think of these things as flushing like lavatories every now and again," said Professor Wingham.

It was once speculated that Lake Vostok, which contains enough water to supply London for 5,000 years, may have generated huge floods that reached the coast at some point in its history.

The latest research raises the prospect that the same thing could happen again. "Currently, we don't know how full Lake Vostok is or the length of time it will take to fill," said Professor Siegert. "It might be thousands or even tens of thousands of years. Whether such a discharge could affect the ocean circulation around Antarctica is an open question at this stage."

He said any discharge would probably take place over a period of months and would change sea level by less than a centimetre.
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