Over the past two decades, the thickness of Antarctica’s floating ice shelves has declined by up to 18% in certain areas, researchers at the Scripps Institution of Oceanography at UC San Diego and Earth & Space Research in Oregon reported on Thursday.
The scientists, who published their findings in the academic journal Science, said their findings provide new insights on how climate change is affecting the Antarctic ice sheet.
The NASA-supported study found that according to data from satellite missions from 1994 to 2012, ice volume decline in Antarctica is accelerating.
Eighteen years of change in thickness and volume of Antarctic ice shelves. (Image: Scripps Institution of Oceanography, UC San Diego)
Fernando Paolo, a Scripps graduate student, Helen Amanda Fricker, a Scripps glaciologist, and Laurie Padma, an oceanographer at Earth & Space Research, constructed a new high-resolution record of ice shelf thickness based on ESA’s (European Space Agency’s) satellite radar altimetry missions.
By merging data from three overlapping missions, the scientists identified changes in ice thickness that occurred over more than ten years, which was an advancement over analyzing data from single missions that only provide snapshots of trends.
Ice shelf volume down since 2003
From 1994 to 2003, total ice shelf volume – mean thickness times ice shelf area – changed very little across Antarctica. However, after 2003 it declined rapidly.
Throughout the whole 18-year observation period, ice shelves in West Antarctica lost ice, with the loss occurring at a faster rate over the last decade.
Earlier gains observed in East Antarctic ice shelf volume came to a halt in 2003, the researchers found. Some ice shelves have lost up to 18% of their volume since 1994.
“Eighteen percent over the course of 18 years is really a substantial change. Overall, we show not only the total ice shelf volume is decreasing, but we see an acceleration in the last decade.”
Melting ice shelves do not necessarily contribute directly to rising sea levels. However, the researchers believe there is an important indirect effect.
The rate of thickness change in the Antarctic Peninsula increases spatially with time from north to south in the Larsen Ice Shelf. The eastern (Weddell Sea) side of the Antarctic Peninsula (top) shows independent behavior from the western (Bellingshausen Sea) side (bottom). (Image: Scripps Institution of Oceanography, UC San Diego)
Affects flow from grounded ice into the ocean
Prof. Fricker said:
“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.”
If the thinning continues at its current rate, the ice shelves could lose half their volume within the next 200 years, the researchers estimated.
Thomas Wagner, Program Manager for Cryospheric Sciences at NASA Headquarters, said:
“This work demonstrates the power of satellite observations to understand change in the great polar ice sheets. And with data spanning decades, we can understand some of the most important changes and their implications for sea-level rise.”
Future studies will focus on the causes behind the thinning of the ice shelf, Prof. Flicker said, including the effects of the ocean and atmosphere.
Mr. Paolo said:
“We’re looking into connections between El Niño events in the tropical Pacific and changes in the Antarctic ice sheet. It’s very far apart but we know that these teleconnections exist. That may ultimately allow us to improve our models for predicting future ice loss.”
Citation: “Volume loss from Antarctic ice shelves is accelerating,” Fernando S. Paolo1,*, Helen A. Fricker1, Laurie Padman. Science. Published on March 26, 2015. DOI: 10.1126/science.aaa0940.