A novel use of satellite data is giving scientists insight into what is going on beneath the surface of ice in West Antarctica.
It will also aid understanding of how fast glaciers in the region flow towards the ocean.
Understanding the movements of glaciers is critical for predicting how the ice sheet may behave in the future and how it may affect sea level.
New information, from the European Space Agency’s CryoSat mission, has revealed how lakes beneath West Antarctica’s Thwaites Glacier recently drained into the Amundsen Sea.
Drainage from the glacier is estimated to have peaked at about 240 cubic metres a second, possibly the largest outflow of meltwater ever reported from subglacial lakes in this region.
Thwaites Glacier, and its neighbour Pine Island Glacier, are the fastest receding glaciers on the Western Antarctic Ice Sheet.
Although the Antarctic ice sheet is some 2 km thick in places, much of its floor is well below sea level.
This makes it is particularly vulnerable to change, especially where warmer ocean waters meet the underside of the floating edge of the glacier.
Research published today in The Cryosphere explains how CryoSat measurements have been processed in a new way.
The study reveals that, in 2013, four interlinked lakes under Thwaites Glacier drained into the ocean.
Lakes have been found under glaciers in many parts of Antarctica and are commonly associated with fast-flowing glaciers.
However, this is the first time they have been found and observed draining into the Amundsen Sea. In addition, this emptying is thought to happen only every 20–80 years.
Water below the ice sheet plays an important role in how quickly glaciers flow towards the sea.
This may be because a layer of meltwater reduces friction between the ice and the bedrock.
In addition, when channels form under the ice they lubricate the glacier bed.
The study, carried out in collaboration with the University of Washington, was funded by the European Space Agency.
Repeat observations from CryoSat over Thwaites Glacier revealed that the surface of the ice subsided by several metres as water drained away from four lakes under the ice. The lakes totalled an area of about 700 sq km.