Almost 100 volcanoes have been newly identified beneath the ice covering West Antarctica. It’s not yet known whether they’re active, but if they are, it could spell added trouble for ice sheets already in retreat because of global warming.
“If they erupted, they would create water beneath the ice,” says Robert Bingham at the University of Edinburgh, UK. “That would make the ice above flow faster, so it would have the potential to increase the losses of ice we’re already seeing.”
Bingham and his colleagues identified the volcanoes by examining an existing data set called Bedmap2, a collection of ground-penetrating radar scans made from aeroplanes or vehicles above or on the surface.
The scans show the profile of the rock some 4 kilometres beneath the ice, and the team identified all conical structures as possible volcanoes. “No one had interrogated the data before for shapes,” says Bingham.
Next, the researchers checked to see whether the cones tallied with other data from satellite imagery, such as subtle deformations on the ice surface directly above possible volcanoes, and telltale variations in gravity and magnetic fields. “We found 180 cones, but discounted 50 because they weren’t matched with the other data,” says Bingham.
They settled on a final tally of 138 beneath the West Antarctic ice sheet, which includes 47 volcanoes already known because their peaks protrude through the ice – leaving 91 newly discovered. The volcanoes range in height from 100 to 3850 metres, with 29 higher than 1 km.
Bingham suspects that more volcanoes may lurk beneath the neighbouring Ross ice shelf, for which ground-penetrating radar information is sparse. If so, it could mean that the West Antarctic ice sheet and the adjoining area hide one of the world’s largest volcanic systems, comparable with the largest known – the East African rift system.
The team now wants to deploy instruments to find out how active the volcanoes are. But even if they are active, Eric Rignot at NASA’s Jet Propulsion Laboratory in Pasadena, California, thinks the effect on the ice will be relatively minor – and that the main threat to the ice sheets is warmer ocean water. “This ocean heat largely surpasses what could ever be produced by a few active volcanoes,” he says.
What lurks in Antarctica’s bedrock?, Andy Coghlan, Geological Society, London, Special Publications, DOI: 10.1144/SP461.7, 15 August 2017