Con­ti­nen­tal ice mas­ses in wes­tern Ant­ar­c­ti­ca are belie­ved to be less sta­ble than their coun­ter­parts in East Ant­ar­c­ti­ca. Most likely, they are alre­a­dy making a signi­fi­cant con­tri­bu­ti­on to glo­bal sea level rise. This con­tri­bu­ti­on may even increase stron­gly in the future. One reason is that ice mas­ses in wes­tern Ant­ar­c­ti­ca rest on the ground below sea level over lar­ge are­as. Loss of shelf ice, which has a sta­bi­li­zing effect on gla­ciers in the catch­ment area, are ano­ther fac­tor.

The ice loss has now been exami­ned and con­firm­ed with 4 inde­pen­dent methods. Ear­lier stu­dies focus­sed on one method only, lea­ving the pos­si­bi­li­ty of unde­tec­ted metho­di­cal errors. This risk is eli­mi­na­ted by using 4 inde­pen­dent methods. The­se are laser and radar alti­me­try time-varia­ble gra­vi­ty, sur­face mass balan­ce, and radar-based ice velo­ci­ty and ice thic­k­ness mea­su­re­ments. All methods con­firm the ice loss and its acce­le­ra­ti­on in recent years.

Over the who­le stu­dy peri­od from 1992 to 2013, the ice loss is mea­su­red at 83±5 Gt/yr (bil­li­on tons per year), with an acce­le­ra­ti­on of 6.1±0.7 Gt/yr2. Loo­king only at the more recent years 2003-2009, the resul­ting ice loss is 84±10 Gt, no signi­fi­cant chan­ge. But the acce­le­ra­ti­on has almost tri­pled to 16.3±5.6 Gt/yr2. Inclu­ding 2 more years, loo­king at 2003-2011, yields a hig­her ice loss rate of 102±10 Gt/yr and an acce­le­ra­ti­on of 15.7±4.0 Gt/yr2.

The increase of acce­le­ra­ti­on is reason for con­cern. Curr­ent­ly, con­ti­nen­tal wes­tern Ant­ar­c­ti­ca ice mas­ses are esti­ma­ted to con­tri­bu­te with 0.3 mm/yr to glo­bal sea level rise.

Source: Geo­phy­si­cal Rese­arch Let­ters