Four different measurement techniques and a comprehensive study across 21 years have revealed that the melt rate of glaciers in west Antarctica has tripled in the last decade. The glaciers lost water equivalent to Mt Everest's-worth every two years over the last 21 years.

The UCI-Nasa study of glaciers in the Amundsen Sea Embayment in West Antarctica shows melting in this part of Antarctica is shifting into high gear.

"Previous studies had suggested that this region is starting to change very dramatically since the 1990s, and we wanted to see how all the different techniques compared," lead author Tyler Sutterley, a UCI doctoral candidate, said. "The remarkable agreement among the techniques gave us confidence that we are getting this right."

According to Nasa, glaciers in the Amundsen region hold water that can raise sea levels by four feet.

Measurements from 1992 to 2013 of the mass balance of glaciers flowing into the Amundsen Sea Embayment showed an accelerated rate of loss averaging six billion tonnes per year since 1992.

The mass balance measures how much ice the glaciers gain and lose over time from accumulating or melting snow, discharges of ice as icebergs, and other causes.

The researchers calculated the total amount of loss, and the changes in the rate of loss.

The total amount of loss averaged 83 billion tonnes per year (91.5 billion US tons). By comparison, Mt Everest weighs about 161 billion tonnes.

From 2003 to 2009, when all four observational techniques overlapped, the melt rate increased an average of 16.3 billion tonnes per year — almost three times the rate of increase for the full 21-year period.

The observations include those from Nasa's Gravity Recovery and Climate Experiment (GRACE) satellites, laser altimetry from Nasa's Operation IceBridge airborne campaign and earlier ICESat satellite, radar altimetry from the European Space Agency's Envisat satellite, and mass budget analyses using radars and the University of Utrecht's Regional Atmospheric Climate Model.

Earlier studies have shown rapid ice melt in the northern region of the continent as well as a bounce effect on the earth's crust. A recently discovered active volcano further adds to fears of ice melt and sea level rise.