A new study, published in the journal Science, combines satellite data to track the health of Antarctica’s floating ice shelves shows that they have decreased by as much as 18 percent over the last two decades. This provides a longer range snapshot of how the Antarctic ice sheet is responding to climate change than previous studies.
The researchers analyzed data from two decades of satellite radar altimetry data, gathered by missions of the European Space Agency between 1994 and 2012. They used the data to create a high-resolution record of ice shelf thickness and were able to show that not only is the ice volume declining but the rate of that decline is accelerating.
The data showed that the total volume of the ice shelf (“mean thickness multiplied by ice shelf area”) changed only a little between 1994 an 2003. After that however, a much more rapid decline began. Volume in the West Antarctic ice shelves declined
“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,” said Fernando Paolo, graduate student at the Scripps Institution of Oceanography at UC San Diego, in a statement.
The Antarctic ice shelves do not contribute directly to sea level rise, as they are already over water, they do play a vital indirect role.
“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.
The floating ice shelves, in other words, act as a sort of dam which prevents water runoff from the ground based ice sheet from reaching the sea. The mounting of ground based ice does increase sea levels.
According to Fricker, the research will continue and the team will next look at the causes behind the ice shelf volume declines including changes in the atmosphere and ocean.
“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,” said Paolo.
News of the reduction in the Antarctic ice shelves comes almost simultaneously with a report from geophysicists from the Jackson School of Geosciences at the University of Texas at Austin which shows that the East Antarctic Totten Glacier is in danger. The researchers in that case were able to show that two seafloor gateways appear to be allowing warm water to flow into the interior of the glacier, causing an increase in melting.
Meanwhile, on the other side of the world, the U.S. National Snow and Ice Data Center (NSIDC) is reporting that winter sea ice coverage in the arctic has hit a record low, which could imply a negative trend as we head toward the summer low.
“A less than 1m sq km summer would mean that the north pole would be open water, that a broad seaway would exist north of Siberia and that major ecosystems and fauna would be severely impacted. My own guess is that we will reach this level around 2030,” NSIDC’s senior research scientist Ted Scambos told the Guardian.
