Antarctica is now losing its ice at the rate of 160 billion metric tons a year, which is twice as much as when it was last surveyed.
Scientist from the UK Centre for Polar Observation and Modelling used 3 years of data collected by the the European Space Agency’s CryoSat-2 satellite mission, to produce the first comprehensive assessment of Antarctic ice sheet elevation change.
The sattelite carries a high-tech altimeter instrument specially designed to detect elevation change in ice sheet that includes coastal and high-latitute regions of Antarctica.
CryoSat-2 provides 96% coverage of the entire continent, extending to within 215 kilometres of the South Pole and and leading to a fivefold increase in the sampling of coastal regions where the vast majority of all ice losses occur.
“Although we are fortunate to now have, in CryoSat, a routine capability to monitor the polar ice sheets, the increased thinning we have detected in West Antarctica is a worrying development,” said professor Andrew Shepherd of the University of Leeds, who led the study.
“It adds concrete evidence that dramatic changes are underway in this part of our planet.”
Three years of observations, between 2010 and 2013, have estimated that on average, West Antarctica lost 134 gigatonnes of ice, East Antarctica three gigatonnes, and the Antarctic Peninsula 23 gigatonnes a year – a total loss of 159 gigatonnes each year.
The polar ice sheets contribute the most to global sea level rise and the losses in Antarctica alone are enough to raise levels by 0.45mm every year.
In West Antarctica, depletion of ice has been noticed in areas that were poorly surveyed by past missions.
These newly-mapped areas contribute additional losses that bring altimeter observations closer to estimates based on other approaches, said researchers.
In West Antarctica, the average rate of ice thinning has increased and it’s losing almost 31% as much ice each year than it did during the past five years survey (2005-2010) prior to CryoSat-2’s launch.
“We find that ice losses continue to be most pronounced along the fast-flowing ice streams of the Amundsen Sea sector, with thinning rates of between 4 and 8 metres per year near to the grounding lines of the Pine Island, Thwaites and Smith Glaciers,” said lead author Dr Malcolm McMillan from the University of Leeds.
Researchers say this sector is most vulnerable to climate change and, according to recent assessments, its glaciers may have passed a point of irreversible retreat.
“Thanks to its novel instrument design and to its near-polar orbit, CryoSat allows us to survey coastal and high-latitude regions of Antarctica that were beyond the capability of past altimeter missions, and it seems that these regions are crucial for determining the overall imbalance,” said Professor Andrew Shepherd.