Antarctic ice shelves rapidly thinning: study

The thickness of Antarctica's floating ice shelves has decreased by 18 per cent in certain areas over nearly two decades, warns a study that provides insights on how the ice sheet is responding to climate change.
Data from nearly two decades of satellite missions have shown that the ice volume decline is accelerating, researchers said.
The research team led by the Scripps Institution of Oceanography at University of California, San Diego constructed a new high-resolution record of ice shelf thickness based on satellite radar altimetry missions of the European Space Agency from 1994 to 2012.
Merging data from three overlapping missions, researchers identified changes in ice thickness that took place over more than a decade, an advancement over studying data from single missions that only provide snapshots of trends.

Total ice shelf volume (mean thickness multiplied by ice shelf area) across Antarctica changed very little from 1994 to 2003, then declined rapidly, the study shows.
West Antarctic ice shelves lost ice throughout the entire observation period, with accelerated loss in the most recent decade.

Earlier gains in East Antarctic ice shelf volume ceased after about 2003, the study showed. Some ice shelves lost up to 18 per cent of their volume from 1994 to 2012.
"Eighteen per cent over the course of 18 years is really a substantial change," said Scripps graduate student Fernando Paolo.
"Overall, we show not only the total ice shelf volume is decreasing, but we see an acceleration in the last decade," Paolo said.

While melting ice shelves do not contribute directly to sea-level rise, the researchers indicate that there is an important indirect effect.
"The ice shelves buttress the flow from grounded ice into the ocean, and that flow impacts sea-level rise, so that's a key concern from our new study," said Scripps glaciologist Helen Amanda Fricker.
Under current rates of thinning, the researchers estimate the ice shelves restraining the unstable sector of West Antarctica could lose half their volume within the next 200 years.
The study was published in the journal Science.