A 21-year analysis of Antarctica's fastest-melting region shows the melt rate of glaciers there tripled during the past decade, according to new research by UC Irvine and NASA's Jet Propulsion Laboratory (JPL) in Pasadena.
(Some data came from NASA's Gravity Recovery and Climate Experiment or GRACE satellites that played a starring role in the recent Weekly cover story "An Inconvenient Thirst: Rain Can't Save Us From This Drought.")
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, according to the study, which 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," says UCI/JPL scientist Isabella Velicogna–who co-authored a paper on the results that will be in the Dec. 5 publication of the journal Geophysical Research Letters–in a university statement.
"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," says Tyler Sutterley, the lead author and a UCI doctoral candidate, in the same release. "The remarkable agreement among the techniques gave us confidence that we are getting this right."
What they're getting right: The melting in that part of Antarctica is shifting into high gear. Looking at 1992 through 2013, the glaciers flowing into the Amundsen Sea Embayment lost 83 gigatons per year (91.5 billion U.S. tons). By comparison, Mt. Everest weighs about 161 gigatons, so the Antarctic glaciers lost a Mt.-Everest's-worth amount of water weight every two years over the last 21 years. The melt rate increased an average of 16.3 gigatons per year from 2003-'09–almost three times the rate of increase for the full 21-year period.
This was confirmed by matching the data from four sets of observations, which include GRACE, 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.
"We have an excellent observing network now," notes Velicogna. "It's critical that we maintain this network to continue monitoring the changes because the changes are proceeding very fast."
So much for glacial speed.