Antarctica lost 3 trillion tonnes of ice in blink of an eye
Wednesday, June 13, 2018, 5:46 PM - Antarctica has lost trillions of tonnes of ice to global warming over the past quarter of a century, according to a new study, and that loss has been accelerating in recent years, to triple the rate that was seen prior to 2012.
The East and West Antarctic ice sheets have enough mass accumulated to raise the world's ocean levels by a staggering 58 metres if it all melted - enough to submerge a 14-story office building - and as the planet continues to warm due to the increase in greenhouse gases in the atmosphere, we are picking away at ice mass at a faster and faster rate.
According to a new study by the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE), now considered to be the most complete and up-to-date picture of the changes happening to the Antarctic ice sheet, satellites had been recording a fairly steady rate of ice loss from Antarctica, of around 76 billion tonnes per year, between 1992 and 2012. After 2012, however, the losses have skyrocketed to nearly triple that amount - 219 billion tonnes of ice lost per year, up until 2017.
In total, that amounts to nearly 3 trillion tonnes of ice lost, in just 25 years time.
Spread out over the roughly 360 million square kilometers of Earth's oceans, that accounts to over 7 millimetres of sea level rise - directly from the additional volume of water. Total sea level rise from all sources, including thermal expansion of the warming oceans, has been recorded by NASA at roughly 87 millimetres by the end of 2017.
Changes in global sea level, from 1992 to 2017, due to contributions from the Antarctic ice sheet. The total contribution is highlighted by the bold white line, while the blue lines track the individual contributions from East Antarctic, the Antarctic Peninsula and West Antarctica. Credit: IMBIE/Planetary Visions
"We have long suspected that changes in Earth’s climate will affect the polar ice sheets. Thanks to the satellites our space agencies have launched, we can now track their ice losses and global sea level contribution with confidence," Professor Andrew Shepherd, the lead researcher of the study from the University of Leeds, said in a press release on Wednesday. As part of IMBIE, Professor Shepherd coordinated with 83 other scientists, from 44 international organizations, to combine the data from two dozen different satellite surveys for this comprehensive look at the changes in Antarctica's ice mass balance.
"According to our analysis, there has been a step increase in ice losses from Antarctica during the past decade, and the continent is causing sea levels to rise faster today than at any time in the past 25 years," Shepherd said. "This has to be a concern for the governments we trust to protect our coastal cities and communities."
Watch below to see where the Antarctic ice sheet has been suffering its greatest losses over the past 25 years.
As shown in the video above, these changes are not uniform over the entire Antarctic ice sheet.
West Antarctica is currently bearing the brunt of this loss, as its glacial ice shelves have been melted from below by warming deep ocean water. According to the study, the rate of loss in that part of the content has increased from 53 billion tonnes per year in the 1990s, up to the current rate of 159 billion tonnes per year. The Antarctic Peninsula - the portion of the continent that reaches out for the southern tip of South America - has seen an increase from an average of 7 billion tonnes per year, up to 33 billion tonnes per year in that same time period.
Only East Antarctica has actually seen an overall increase in mass over the 25 years, amounting to an average of 5 billion tonnes per year. This increase has been very small compared to the losses recorded from the rest of the ice sheet, though.
According to NASA, the data for this study was gathered by over a dozen different satellites - NASA's ICESat mission, the NASA/German Aerospace Center twin GRACE satellites, the European Space Agency's Envisat and CryoSat-2 satellites, the German Aerospace Center TerraSAR-X satellite, the European Union's Sentinel-1 and Sentinel-2 satellites, the Italian Space Agency's COSMO-SkyMed satellite constellation, the Japan Aerospace Exploration Agency's Advanced Land Observatory System, and the Canadian Space Agency's RADARSAT-1 and RADARSAT-2 satellites.
"Satellites have given us an amazing, continent-wide picture of how Antarctica is changing," said Dr. Pippa Whitehouse, a member of the IMBIE team from Durham University, according to a University of Leeds press release. "The length of the satellite record now makes it possible for us to identify regions that have been undergoing sustained ice loss for over a decade."
"The next piece of the puzzle is to understand the processes driving this change," Whitehouse added. "To do this, we need to keep watching the ice sheet closely, but we also need to look back in time and try to understand how the ice sheet responded to past climate change."