24% of the ice of West Antarctica is now unstable

By combining 25 years of satellite altimetry measurements from the European Space Agency and a regional climate model, the British Center for Polar Observations and Modeling (CPOM) has tracked the evolution of the coverage of snow and ice on the mainland.

A team of researchers, led by Professor Andy Shepherd of the University of Leeds, discovered that the Antarctic ice floe had thinned up to 122 meters, the fastest changes occurring in West Antarctica, where the melting oceans has caused glacial imbalance.

This means that affected glaciers are unstable because they lose more mass during melting and calving than they do win under the snow.

The team found that the pattern of thinning glaciers was not static. Since 1992, the thinning has spread to 24% of western Antarctica and to most of its larger ice currents – the Pine Island and Thwaites glaciers – which now lose ice five times faster than at the beginning of the survey.

The study, published today in Geophysical Research Letters, used more than 800 million measurements of the Antarctic ice sheet height recorded by the ERS-1, ERS-2, Envisat and CryoSat-2 satellite altimetry missions between 1992 and 2017, as well as snowfall simulations on the same period produced by the regional climate model RACMO.

Together, these measures separate changes in ice cap height as a function of weather conditions, such as reduced snowfall, and those due to long-term climate change, such as rising temperatures of the ice sheet. ocean that destroy the ice.

Professor Andy Shepherd, senior author and director of the CPOM, explained: "In parts of Antarctica, the ice sheet has become considerably thinned, so we wanted to show how much climate change and those due to weather conditions were at the origin of the change. "

To do this, the team compared the measured height change from the measured surface to the simulated snowfall changes and, where the gap was larger, they attributed its origin to glacial imbalance.

They found that fluctuations in snowfall tend to result in small changes in height over large areas for several years, but the most pronounced changes in the thickness of the ice are signs of imbalance of glaciers that have persisted for decades.

Professor Shepherd added, "Knowing how much snow has fallen has really helped us detect the underlying change of glacial ice in the satellite record.We can now clearly see that a wave of Thinning has quickly spread to some of Antarctica's most vulnerable glaciers as their losses raise sea levels around the planet.

"In total, ice losses from the east and west of the Antarctic have contributed 4.6 mm to sea level rise globally since 1992. . "

Dr Marcus Engdahl of the European Space Agency, co-author of the study, added: "This is an important demonstration of how satellite missions can help us understand the evolution of our planet. polar are hostile and extremely difficult environments to access from the ground.For this reason, the view from space is an essential tool for monitoring the effects of climate change. "

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The document Antarctic Ice-Level Altitude and Mass Trends is published in Geophysical Research Letters May 16, 2019 DOI: 10.1029 / 2019GL082182

The satellite radar altimetry time series ERS-1, ERS-2, ENVISAT and CryoSat-2 produced as part of this study were funded by the Agency's Council Initiative. Europe on climate change and are available for free at the following address: http: // www.CPOM.UCL.acUnited Kingdom/csopr /ice caps /Mass.html

The data from the RACMO regional climate model used in this study were provided by Michiel van den Broeke and Stefan Ligtenberg of the University of Utrecht.

Professor Andy Shepherd is available for comment: [email protected]

For more information, please contact Leeds University Press Officer Anna Harrison [email protected] or +44 (0) 113 34 34196.

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