Three years of observations from Europe’s CryoSat satellite show that the Antarctic ice sheet is now losing 159 billion tonnes of ice each year – twice as much as when it was last surveyed.

The polar ice sheets are a major contributor to the rise in global sea levels - the newly measured losses from Antarctica alone are enough to raise global sea levels by 0.45 mm each year.

The latest findings by a team of scientists from the UK’s Centre for Polar Observation and Modelling show that the pattern of imbalance continues to be dominated by glaciers thinning in the Amundsen Sea sector of West Antarctica.

Between 2010 and 2013, West Antarctica, East Antarctica and the Antarctic Peninsula lost 134, 3 and 23 billion tonnes of ice each year, respectively.

The average rate of ice thinning in West Antarctica has increased compared to previous measurements, and this area’s yearly loss is now one third more than measured over the five years before CryoSat’s launch.

Launched in 2010, CryoSat carries a radar altimeter that can measure the surface height variation of ice in fine detail, allowing scientists to record changes in its volume with unprecedented accuracy. s The satellite’s novel instrument design and near-polar orbit has enabled the scientists to survey coastal and high-latitude regions of Antarctica that were beyond the capability of past altimeter missions.

CryoSat surveys almost all – 96% – of the Antarctic continent, reaching to within 215 km of the South Pole. In addition, it has increased coverage over coastal regions, where today’s ice losses are concentrated.

Professor Andrew Shepherd from the University of Leeds, UK, who led the study, said  the increased thinning detected in West Antarctica was a worrying development. The area has long been identified as the most vulnerable to changes in climate and recent assessments say its glaciers may have passed a point of irreversible retreat. The thinning adds concrete evidence that dramatic changes are now under way in this part of the planet.