In the past 25 years, the Antarctic ice sheet has been diluted to 122 meters in certain areas. The worst affected area is West Antarctica, where the melting of the ocean speeds up the process. However, affected glaciers are becoming unstable everywhere in the frozen continent, a new article reports, meaning that they lose more ice by melting and cooling than they get by snowfall.
The authors of the study, a team from the UK Center for Polar Observation and Modeling (CPOM) led by Professor Andy Shepherd of the University of Leeds, used altitude measurement data captured by satellites from the European Space Agency and a regional climate model for 25 years. condition of the Antarctic ice.
Antarctica, shaken, no ice, please
"In parts of Antarctica, the ice sheet has been thinned with extraordinary amounts, so we wanted to show how much was due to climate change and how much was due to the weather," explains Professor Shepherd.
"Although most of the ice sheet has remained stable, 24% of West Antarctica is now in a state of dynamic imbalance," the newspaper said.
The glacier's thinning patterns are not static, the team reports. Since 1992, glaciers across more than 24% of West Antarctica has begun to become thinner, just like those of the continent's largest ice flows – the Pine Island and Thwaites Glaciers. These two glaciers are now melting a full five times faster than at the start of the study, the team notes. All in all, fluctuations in snowfall cause small changes in the volume of the glacier for a few years a time, but the significant changes observed by the team persisted for decades and are indicative of the effects of climate change instability of the glacier, the team explains.
The data used in the study included more than 800 million measurements of the height of the ice sheet in Antarctica registered by the ERS-1, ERS-2, Envisat and CryoSat-2 satellite altimeter tasks between 1992 and 2017 and simulations of snowfall in the same produced by the RACMO regional climate model. Thanks to this wealth of data, the team was able to distinguish changes in ice sheet height due to weather conditions – such as variations in snowfall – from long-term changes caused by the climate, such as warmer ocean water that melts ice. To separate the two effects, the researchers compared the measured surface heights in the field with snowfall changes they simulated with the RACMO model. In fact, any discrepancies between the two data sets are the product of glacier imbalance (that is, climate change).
"Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice in the satellite record," says Professor Shepherd. "We can now clearly see that a wave of thinning has spread rapidly over some of the most vulnerable glaciers in Antarctica, and their losses are driving up the sea level around the planet."
"Altogether, ice losses in East and West Antarctica have contributed 4.6 mm since 1992 to global sea level rise."
The study is a good example of how satellite data can be used to study major climate trends that are going on on our planet. This is especially true in hostile environments such as the Arctic and Antarctic, where ground level missions are not only difficult but potentially fatal.
The article "Trends in Antarctic Ice Sheet Elevation and Mass" is published in the magazine Geophysical Research Letters.