Scientists have discovered that 40 percent of Antarctica’s ice shelves have significantly reduced in volume over the past quarter-century. This alarming revelation points to the accelerating impact of climate change on the world’s southernmost continent.
The loss of the ice shelves threatens to accelerate glaciers flowing into the sea, potentially raising ocean levels worldwide. It also increases the risk of an irreversible tipping point – beyond which Antarctica’s polar ecosystem as we know it may no longer survive.
A recent study of ice shelf thinning reveals the worst decline in decades. Researchers from the Scripps Institution of Oceanography in California analyzed 18 years of satellite radar images of Antarctica’s ice sheets and floating ice shelves. The results show that the ice shelves are shrinking fast, and no sign of recovery exists.
Scientists use ice shelves as buttresses to hold back the glaciers that flow into the sea. They take thousands of years to form and act like “gatekeepers,” keeping the glaciers from flowing too rapidly into the water and causing sea levels to rise more quickly. When ice shelves are thin enough, they collapse, and the massive glaciers behind them slide into the sea, which raises global ocean levels.
This is a significant concern, as Antarctica holds 88% of the world’s potential sea level contribution. A thinning ice sheet is a lot like a glass full of water. Adding another ice cube could cause the glass to spill over.
Ice shelves are also critical to the habitat of Antarctic wildlife. From tiny crustaceans such as Antarctic krill to the largest penguin species, the animals of Antarctica rely on sea-ice habitats for survival. This habitat is rapidly declining, with record-low sea-ice coverage for the past two years.
The thinning ice shelves are because warmer waters are rising beneath Antarctica, and this warm water melts the ice shelf from underneath. As the ice shelf melts, plumes of colder water rise from beneath, which counteracts the warming effect of the upwelling.
The research shows that the collapse of ice shelves is a global phenomenon, with some areas of Antarctica losing much more ice than others. The fastest rate of ice loss comes from the western side of Antarctica, where centuries-old glaciers are draining into the Amundsen Sea. The Thwaites glacier – nicknamed ‘Doomsday Glacier’ – has lost about 70% of its ice shelf mass since 1997.
The research was funded by ESA’s Earth Observation Science for Society program and published in the journal Science Advances. Science Advances is a multidisciplinary open-access journal in the Science family of journals. It was launched in early 2015 and is published by the American Association for the Advancement of Science. It has been described as a leading international journal with high visibility and readership. For more information, visit the Science Advances website.