Antarctic glaciers revolve around the concept of “glacial rhythm”. A new study of a little-observed area of the continent finds that rising heat causes ice currents to flow faster, which has worrying consequences for rising sea levels.
He to study, published this week in Nature Communications, uses a quarter-century of satellite records to observe changes in the Getz ice shelf in West Antarctica. The study “is the first to show that this region is accelerating over long periods of multi-decade time,” author Heather Selley said in an email. “Only with detailed maps of where changes are taking place can we investigate the physical process that leads to change.”
Selley explained that although scientists had previously observed changes in ice levels in the Getz region, they could not be sure if it was due to atmospheric processes, such as snowfall or surface ice melting. or changes in ice speed. The latter is driven by warmer ocean water that reduces floating ice and points to worrying impacts of climate change. The new study allows scientists to more specifically link long-term ocean warming to changes in the ice shelf.
The results are pretty amazing. The speed of the 14 glaciers surveyed increased by an average of almost 23% between 1994 and 2018. Three of these glaciers accelerated by more than 44%. A particularly fast flow of ice was moving 59% faster than two decades ago.
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Ice loss also increased dramatically. Glaciers lost 315 gigatons of ice, enough to fill 126 million Olympic pools, during that time period. And the loss has accelerated dramatically in recent years. Between 1994 and 1999 and from 2000 to 2009, the area lost 5.6 and 5.8 gigatonnes per year, respectively. But between 2010 and 2018, the ice loss rate soared to 24.8 gigatons of ice loss a year. This great loss is responsible just over 10% of the total contribution of Antarctica to sea level rise since the early 1990s.
The Getz ice shelf is located in an area of great importance for understanding sea level rise, but relatively little is known about the region. Getz is not exactly on the list of tourist destinations for Antarctic cruises. It’s so remote that no humans have stepped on portions of the region, and nine of the study’s 14 glaciers don’t even have a name.
“There are only a handful of studies on Getz compared to hundreds of glaciers in the Amundsen maritime sector (Thwaites and Pine Island),” Selley noted. “This study shows that the percentage acceleration of Getz Glaciers is comparable to the acceleration measured at Thwaites and Pine Island, showing the importance of the Getz region in relation to the fastest-changing glaciers in Antarctica.”
Thwaites and Pine Island are among the most endangered glaciers in Antarctica. Researchers on a trip to Thwaites last year drilled into the floating part of the glacier and searched direct observations of warm sea water flowing beneath. David Holland, a New York University glaciologist who conducted the research, dit in a press release at the time that “suggests it could be suffering an unstoppable setback that has huge implications for rising global sea levels.”
New findings on the Getz region add another layer of concern. Antarctica has a huge impact on sea level rise around the world and understanding how ice behaves on the continent is increasingly crucial to figuring out how far we can raise sea level. Also, the ice shelves that collapse in the region behave a bit like the corks coming out of a bottle of wine, releasing a torrent of ice into the sea and creating more instability and melting in the region. The glaciers of Thwaites and Pine Island, for example, are the cork on land ice that, if it went into the ocean, could push the seas 10 feet (3.1 meters) or more. Paying more attention to the way little-studied areas like Getz are located will be important in preparing for the future.
“If we don’t understand why changes are happening, we won’t be able to accurately model change,” Selley said. “In turn, this means we cannot reliably predict future ice loss and the contribution of Antarctic sea level.”