Ice losses from Antarctica have tripled since 2012, according to a comprehensive survey by scientists from all over the world.
The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) is a major climate assessment by 84 scientists from 44 international organisations combining data from 24 satellite surveys.
Their findings, published in Nature, show that global sea levels have risen by 7.6mm since 1992, but worryingly, two fifths of this rise happened in the last five years alone.
“We have long suspected that changes in Earth’s climate will affect the polar ice sheets,” said Professor Andrew Shepherd of the University of Leeds, who led the assessment.
“Thanks to the satellites our space agencies have launched, we can now track their ice losses and global sea level contribution with confidence.
“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. This has to be a concern for the governments we trust to protect our coastal cities and communities ,” he added in his statement.
IMBIE previously reported in 2012 that Greenland and Antarctica were losing more than three times as much ice (equivalent to 0.95 mm of sea level rise per year) as they were in the 1990s (equivalent to 0.27 mm of sea level rise per year). But this study is even more comprehensive, according to co-lead Dr Erik Ivins at NASA’s Jet Propulsion Laboratory in California.
“This is the most robust study of the ice mass balance of Antarctica to date,” he said. “It covers a longer period than our 2012 IMBIE study, has a larger pool of participants, and incorporates refinements in our observing capability and an improved ability to assess uncertainties.”
The researchers believe that the worrying jump in ice loss since 2012 is down to both the reduced growth of the East Antarctic ice sheet and increased rates of melt in West Antarctica and the Antarctic Peninsula.
Antarctica’s ice loss is a huge concern for the world, as the continent has the potential to contribute almost 7.5 times more to global sea levels than all other sources of land-held ice on the planet combined. If it all ends up melting, the oceans will rise by 190 feet across the globe.
“Satellites have given us an amazing, continent-wide picture of how Antarctica is changing,” said Dr Pippa Whitehouse, NERC Independent Research Fellow at Durham University.
“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. 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.”
Satellites launched by the European Space Agency and NASA along with agencies in Japan, Canada, Germany and Italy have all provided data for the study.
They showed that West Antarctica has experienced the largest change in the last two decades, with ice losses rising from 53 billion tonnes per year in the 1990s to 159 billion tonnes per year since 2012. Most of this came from the huge Pine Island and Thwaites Glaciers, which are retreating rapidly due to ocean melting.
Meanwhile, the East Antarctic ice sheet has remained practically static in the last 25 years, gaining just five billion tonnes of ice per year on average. And in the north of the continent, ice shelf collapse at the Antarctic Peninsula has driven a 25 billion tonne per year increase in ice loss since the early 2000s.