Quarter of West Antarctic glacier ice unstable, says 25-year satellite study

With the Earth in a state of flux at the moment, we need to keep a particularly close eye on Antarctica. Plenty of satellites are whizzing overhead to do just that, and now a new study has examined 25 years of data they've collected to get a sense of the extent of ice loss across Antarctica. According to the findings, warming waters have destabilized as much as a quarter of the glacier ice in West Antarctica.

The study taps into the eyes in the sky that the European Space Agency (ESA) has had over Antarctica for decades. It takes into account data gathered between 1992 and 2017 by several generations of satellites, including ERS-1, ERS-2, Envisat and CryoSat, all of which use radar altimeters to measure the height of the ice sheet.

This data has been extensively studied in the past, but the new research was designed to sort out which changes in ice sheet elevation could be attributed to glacial ice loss, and which ones were due to shorter-term changes caused by the weather.

To make the distinction, the team used simulations of snowfall over that time, as created by the RACMO regional climate model. The researchers compared the measurements of changes in surface height to what would be expected with snowfall of the time.

They found that natural fluctuations in snowfall created small, short-lived changes in the surface height over large areas. But the biggest changes, which persisted for decades, showed rather drastic ice loss, indicating glacier imbalance.

"Knowing how much snow has fallen has really helped us to isolate the glacier imbalance within the satellite record," says Andy Shepherd, corresponding author of the study. "We can see clearly now that a wave of thinning has spread rapidly across some of Antarctica's most vulnerable glaciers, and their losses are driving up sea levels around the planet."

According to the team, the data shows that since 1992, the pattern of glacier thinning has spread across 24 percent of West Antarctica. In some places, the ice has thinned by as much as 122 m (400 ft), and in areas like Pine Island Glacier and Thwaites Glacier, ice loss is happening five times faster now than it was in the 1990s.

All that water has to go somewhere of course, and the team says the glaciers across East and West Antarctica have raised the global sea levels by 4.6 mm since 1992.

This new study is just the latest brushstroke on the increasingly-detailed picture scientists are painting of Antarctica's grim future. Giant icebergs seem to be breaking off the mainland with alarming regularity, and ice loss rates appear to have tripled since 2012.

The research was published in the journal Geophysical Research Letters.

Source: ESA