Study Finds 24 Percent of West Antarctic Ice is Unstable

Over the past 25 years, ice has thinned across West Antarctica so rapidly that a quarter of its glacier ice is now affected, according to a new study.

Scientists at the Centre for Polar Observation and Modelling (CPOM), based at the University of Leeds in the U.K., have combined 25 years of European Space Agency satellite altimeter measurements and a model of Antarctica’s regional climate to track changes in snow and ice cover across the continent.

The study finds Antarctica’s ice sheet has thinned by up to 122 meters in places, with the most rapid changes occurring in West Antarctica where ocean melting has triggered glacier imbalance. This means the affected glaciers are unstable as they are losing more mass through melting and iceberg calving than they are gaining through snowfall.

Altogether, ice losses from East and West Antarctica have contributed 4.6 millimeters to global sea level rise since 1992, according to the study.

The rate of glacier thinning has not been static over time. Since 1992, the thinning has spread across 24 percent of West Antarctica and over the majority of its largest ice streams – the Pine Island and Thwaites Glaciers – which are now losing ice five times faster than they were at the start of the survey.

The study used over 800 million measurements of the Antarctic ice sheet height recorded by the ERS-1, ERS-2, Envisat, and CryoSat-2 satellite altimeter missions between 1992 and 2017 and simulations of snowfall over the same period produced by the RACMO regional climate model. Together, these measurements allow changes in the ice sheet height to be separated into those due to weather patterns, such as less snowfall, and those due to longer term changes in climate, such as increasing ocean temperatures that eat away ice.