West Antarctic ice melt rate tripled

Washington: The fastest-melting region of Antarctica is losing the equivalent weight in ice of Mount Everest every two years, with the melt rate of glaciers in the region tripling during the last decade, a new study has found.

The glaciers in the Amundsen Sea Embayment in West Antarctica are hemorrhaging ice faster than any other part of Antarctica and are the most significant Antarctic contributors to sea level rise, researchers said.

The study is the first to evaluate and reconcile observations from four different measurement techniques to produce an authoritative estimate of the amount and the rate of loss over the last two decades.

"The mass loss of these glaciers is increasing at an amazing rate," said scientist Isabella Velicogna, jointly of the University of California, Irvine and NASA's Jet Propulsion Laboratory.

Lead author Tyler Sutterley, a UCI doctoral candidate, and his team did the analysis to verify that the 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," Sutterley said.

The researchers reconciled measurements of the mass balance of glaciers flowing into the Amundsen Sea Embayment.

Mass balance is a measure of how much ice the glaciers gain and lose over time from accumulating or melting snow, discharges of ice as icebergs, and other causes.

Measurements from all four techniques were available from 2003 to 2009. Combined, the four data sets span the years 1992 to 2013.

The glaciers in the embayment lost mass throughout the entire period. The researchers calculated two separate quantities: the total amount of loss, and the changes in the rate of loss.

The total amount of loss averaged 83 gigatonnes per year.

By comparison, Mt Everest weighs about 161 gigatonnes, meaning the Antarctic glaciers lost a Mt -Everest's-worth amount of water weight every two years over the last 21 years.

The rate of loss accelerated an average of 6.1 gigatonnes per year since 1992.

From 2003 to 2009, when all four observational techniques overlapped, the melt rate increased an average of 16.3 gigatonnes per year - almost three times the rate of increase for the full 21-year period. The total amount of loss was close to the average at 84 gigatonnes.