Discovery of Antarctic subglacial rivers may challenge excavation plans
21 April 2006
Plans to drill deep beneath the frozen wastes of the Antarctic, to investigate subglacial lakes where ancient life is thought to exist, may have to be reviewed following a discovery by a British team led by UCL (University College London) scientists at the Natural Environment Research Council (NERC)Centre for Polar Observation and Modelling (CPOM).
In a Letter to Nature they report that rivers the size of the Thames have been discovered which are moving water hundreds of miles under the ice. The finding challenges the widely held assumption that the lakes evolved in isolated conditions for several millions years and thus may support microbial life that has evolved 'independently'. It has been suggested that if microbes exist in the lakes, they could function in the same way as those in the subsurface ocean of Jupiter's moon Europa or within subsurface water pockets on Mars.
Professor Duncan Wingham, of UCL, Director of CPOM and who led the team, says: "Previously, it was thought water moves underneath the ice by very slow seepage. 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.
"A major concern has been that by drilling down to the lakes new microbes would be introduced. Our data shows that any contamination will not be limited to one lake, but will over time extend down the length of the network of rivers. We had thought of these lakes as isolated biological laboratories. Now we are going to have to think again."
The discovery, which came as a great surprise to the team, also raises the possibility that large flood waters from deep within the interior may have reached the ocean in the past and may do so again.
Subglacial lakes in Antarctica were first identified in the 1960s. Since then over 150 have been discovered but it is thought thousands may exist, as much of the bed of Antarctica remains un-surveyed. The team focused on the Dome Concordia region in East Antarctica, where more than 40 lakes are known to exist.
Ultra-precise measurements were taken using radars on the European Space Agency ERS-2 satellite to examine in detail small changes in the surface of some of the oldest, thickest ice in Antarctica. The satellite found synchronous changes in the surface height separated by 290 kilometres.
The scientists argue that the only possible explanation of these changes is that a large flow of water must have occurred beneath the ice from one subglacial lake into several others. The finding re-invigorates old speculations that Lake Vostok, which contains 5,400 cubic kilometres of water (equivalent to London's water consumption over 5000 years), may have generated huge floods that could reach the coast.
"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," explains Professor Wingham.
"For the most part, there is very little flow along the string. Then, one of the lakes over pressurises and a flood occurs that fills the next 'bead' down the string. The lakes must be pressurising until the pressure is high enough to force the water under the surrounding ice. Once it starts to flow, it melts the ice, and there is a run-away effect.
"Whether that could start an immediate 'chain reaction' down the string (and hence to the coast), or whether that bead would 'go off' sometime later is a vital question to which we don't know the answer yet. But, sooner or later, the system will be flushed throughout."
Professor Martin Siegert, of the University of Bristol and a co-author of the study, says: "Currently we don't know how full Lake Vostok is or the length of time it will take to fill - 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."
The study was funded by NERC and the ERS-2 satellite was funded by the European Space Agency.
Notes to editors
(1) Several groups, under the umbrella of Scientific Committee on Antarctic Research (SCAR), are currently investigating the prospect of drilling down to subglacial Antarctic lakes. The most advanced UK plans are to explore Lake Ellsworth. Geophysical surveying of the lake will take place in 2007/8 and 2008/9. In two years time the lake's water depth, the thickness of lake-floor sediments and the best place to drill will have been calculated. A proposal will then be submitted by the +30 strong UK-led team to undertake the actual exploration of the lake in 2012/13. Further details can be found at: www.ggy.bris.ac.uk/ellsworth
(2) Title: Rapid discharge connects Antarctic subglacial lakes, Nature (20/04/06)
Authors: Duncan J. Wingham (a), Martin J. Siegert (b), Andrew P. Shepherd (c) and Alan S. Muir (a)
(a) Centre for Polar Observation and Modelling, Department of Space and Climate Physics, Pearson Building, University College London, Gower Street, London WC1E 6BT, UK.
(b) Centre for Polar Observation and Modelling, Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK.
(c) Centre for Polar Observation and Modelling, Scott Polar Research Institute, University of Cambridge, Lensfield Road , Cambridge CB2 1ER, UK.
(3) For further information, please contact:
Judith H Moore, UCL Media Relations, Tel: +44 (0) 20 7679 7678, Mobile: +44 (0)77333 075 96, Out-of-hours: +44 (0)7917 271 364, Email: email@example.com
Professor Duncan Wingham, NERC Centre for Polar Observation and Modelling, Tel: +44 (0) 20 7679 7870, Email: firstname.lastname@example.org
Professor Martin Siegert, NERC Centre for Polar Observation and Modelling, University of Bristol, Tel: +44 (0) 117 928 8902, Email: email@example.com
CPOM is a collaborative research centre jointly funded by the Natural Environment Research Council and is based at three universities: UCL, Bristol and Cambridge. The centre's aim is to study the role of ice, and the large Arctic and Antarctic ice sheets in particular, in the Earth's climate. http://www.cpom.org/
NERC is one of the UK's eight Research Councils. It uses a budget of about £350m a year to fund and carry out impartial scientific research in the sciences of the environment. NERC trains the next generation of independent environmental scientists. It is addressing some of the key questions facing mankind, such as global warming, renewable energy and sustainable economic development. www.nerc.ac.uk