Almost A Quarter Of West Antarctic Ice Has Become Unstable

A team of researchers which is led by Professor Andy Shepherd from the University of Leeds, analyzed that the ice sheet of Antarctica has been thinning up gradually and is now thinned by up to 122 metres in places, with the most frequent changes occurring in West Antarctica where ocean melting has triggered glacier imbalance.

This implies that the affected glaciers are becoming unstable as they lose more mass because of melting and iceberg calving than they are gaining through snowfall.

The team researched that the glacier pattern of thinning has not been static. Since 1992, the thinning has spread across 24% of West Antarctica which covers over the majority of its largest ice streams -- the Pine Island and Thwaites Glaciers. They are now losing ice five times faster than they were at the start of the survey.

A study is published in Geophysical Research Letters which represents over 800 million measurements of the Antarctic ice sheet height which is recorded by the ERS-1, ERS-2, Envisat, and CryoSat-2 satellite altimeter missions. This is recorded in between 1992 and 2017 and simulations of snowfall over the same period produced by the RACMO regional climate model.

Together, these measurements allow modifications in the ice sheet height to be separated into those because of weather patterns, like less snowfall, and those due to longer term changes in climate, like rising ocean temperatures that eat away ice.

Lead author and CPOM Director Professor Andy Shepherd explained that in some parts of Antarctica, the ice sheet has thinned by tremendous amounts, and so they set out to represent how much was because of changes in climate and how much was because of weather.

For this, the team compared the measured surface height change to the simulated modifications in the snowfall, and where the discrepancy was greater, they attributed its origin to glacier imbalance.

They analyzed that changes in snowfall is driving small modifications in height over large areas for a few years at a time, but the largely pronounced changes in ice thickness are signs of glacier imbalance which have persisted for decades.

According to professor Shepherd, knowing how much snow has fallen helped us to know the underlying modification in glacier ice within the satellite record. They can see clearly now that a wave of thinning has spread rapidly on some of Antarctica's most vulnerable glaciers, and their losses are driving up sea levels around the planet.

Dr Marcus Engdahl of the European Space Agency who is also a co-author of the study, informed that this is a very significant representation of how satellite missions can help us to know how our planet is modifying. The polar regions are hostile environments and are extremely tough for accessing from the ground. Because of this, the view from the space is an important tool for tracking the effects of climate change.

By: Preeti Narula

Content: https://www.sciencedaily.com/releases/2019/05/190516114601.htm