West Antarctica has recently been recognized as the region with the greatest density of volcanoes in the world. Scientists have counted 138 volcanoes so far. But the remarkable fact about this is that 91 of them lie as much as 2000 metres below the ice sheet, and they were first discovered in 2017 by a team of scientists from the University of Edinburgh. These subglacial volcanoes are 100 to 3850 metres tall and have basal diameters of 4.5 to 58.5 kilometres. Their numbers are particularly high near Marie Byrd Land and along an axis that runs parallel to the Transantarctic Mountains through the centre of the West Antarctic Rift System.
The news of the discovery of volcanoes beneath the ice attracted great worldwide interest. Scientists were concerned that the eruption of one or more of the subglacial volcanoes could lead to a rapid melting of the West Antarctic Ice Sheet. The direct result of this would be an abrupt global sea-level rise of several metres. Observations from other parts of the world suggest that volcanoes can become active when an overlying ice burden melts. Examples of subglacial volcanic activity have been observed in Iceland, for instance, where eruptions have led to melting on the underside of glaciers, causing a significant increase in the velocity of ice flow. It has not yet been definitively determined whether the volcanoes beneath the West Antarctic Ice Sheet are currently active.

fig. 1.8 > Most of the volcanoes in West Antarctica lie beneath the ice.