Mass Change

By combining 25 years of European Space Agency satellite altimeter measurements and a model of the regional climate, the UK Centre for Polar Observation and Modelling (CPOM) have tracked changes in snow and ice cover across the continent.

Data sets for download

The following data sets are available for download containing the change in mass with time of Antarctica and its constituent drainage basins and major ice sheet regions, calculated from 25 years of satellite altimetry data (ERS-1, ERS-2, ENVISAT and CryoSat-2).

A full explanation of methods and data is given in the paper:

Shepherd, Gilbert, Muir, Konrad, McMillan, Slater, Briggs, Sundal, Hogg, Engdahl: Trends in Antarctic Ice Sheet Elevation and Mass, Geophysical Research Letters, 2019, DOI: 10.1029/2019GL082182.

When using these data, please acknowledge the authors by citing this article.

Data

To access the data please provide us with your contact details so that we can let you know about any future updates. Your details will not be used for any other purpose or passed to any third party.

In only 25 years, ocean melting has caused ice thinning to spread across West Antarctica so rapidly that a quarter of its glacier ice is now affected, according to our new study.

A team of researchers lead by Professor Andy Shepherd from the University of Leeds, found that Antarctica's ice sheet has thinned by up to 122 metres in places, with the most rapid changes occurring in West Antarctica where ocean melting has triggered glacier imbalance. This means that the affected glaciers are unstable as they are losing more mass through melting and iceberg calving than they are gaining through snowfall.

Average rate of AIS elevation change between 1992-2017 from satellite radar altimetry. Black circles at the pole indicate the southern limit of the CryoSat-2 (dashed) and other (solid) satellite orbits. Grey boundaries and numbers show glacier drainage basins and their numeric identifiers (Zwally et al., 2012). Green boundaries show areas of dynamical imbalance in 2017 (dark), 2007 (mid), and 1997 (light). In basins 21 and 22, the area of dynamical imbalance evolves over time.

The team found that the pattern of glacier thinning has not been static. Since 1992, the thinning has spread across 24% 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, published in Geophysical Research Letters on 16th May 2019, 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.

Mass change in East (left) and West (right) Antarctica as determined from satellite altimetry using a classification of areas in a state of ice dynamical imbalance (the optimal solution, black line) and the estimated 1-sigma (67%) uncertainty (grey shaded area). Also shown for comparison are mass changes determined from an alternative altimetry solution directly employing a firn density model and a regional climate model (blue) and from GRACE (red).

In parts of Antarctica the ice sheet has thinned by extraordinary amounts, and so we set out to show how much was due to changes in climate and how much was due to weather.

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

They found that fluctuations in snowfall tend to drive small changes in height over large areas for a few years at a time, but the most pronounced changes in ice thickness are signals of glacier imbalance that have persisted for decades.

Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice within the satellite record. 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.

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

This is an important demonstration of how satellite missions can help us to understand how our planet is changing. The polar regions are hostile environments and are extremely difficult to access from the ground. Because of this, the view from space is an essential tool for tracking the effects of climate change.

Further Information

The paper Trends in Antarctic Ice Sheet Elevation and Mass is published in Geophysical Research Letters 16 May 2019 DOI: 10.1029/2019GL082182

The ERS-1, ERS-2, ENVISAT and CryoSat-2 satellite radar altimetry time-series produced in this study was funded by the European Space Agency Climate Change Initiative and is freely available at the top of this page.

The RACMO regional climate model data 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: a.shepherd@leeds.ac.uk