The glaciers of Antarctica are changing the concept of “glacial rhythm”. A new study of a little-observed area on the continent finds that increased heat is causing ice currents to flow faster, which has worrying consequences for rising sea levels.
the study, published this week in Nature Communications, uses a quarter century of satellite records to observe changes to the Getz Ice Shelf in West Antarctica. The study “is the first to show that this region is accelerating on long, multi-decade time scales,” lead author Heather Selley said by email. “It is only with detailed maps of where the changes are occurring that we can investigate the physical process that drives the change.”
Selley explained that while scientists had previously observed changes in the ice level in the Getz region, they could not be sure if they were due to atmospheric processes, such as less snowfall or melting of surface ice, or changes in the speed of the ice. ice. The latter is driven by warmer ocean water undermining floating ice and pointing to the 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 studied increased by an average of almost 23% between 1994 and 2018. Three of those glaciers increased by more than 44%. A particularly fast flow of ice was moving 59% faster than it was two decades ago.
The loss of ice also increased dramatically. Glaciers lost 315 gigatons of ice, enough to fill 126 million Olympic swimming pools, during that period. And the loss accelerated dramatically in recent years. Between 1994 and 1999 and from 2000 to 2009, the area lost 5.6 and 5.8 gigatons per year, respectively. But between 2010 and 2018, the rate of ice loss skyrocketed to 24.8 gigatons of ice loss per year. This huge loss is responsible for little more than 10% of Antarctica’s total contribution to sea level rise since the early 1990s.
The Getz Ice Shelf is in an area of enormous importance for understanding sea level rise, but comparatively little is known about the region. Getz isn’t exactly on a list of tourist destinations for Antarctic cruises. It’s so remote that no human has ever set foot in parts of the region, and nine of the 14 glaciers in the study don’t even have names.
“There are only a handful of studies on Getz compared to the hundreds of glaciers in the marine sector of Amundsen (Thwaites and Pine Island),” Selley noted. “This study shows that the percentage acceleration of the Getz glaciers is comparable to the acceleration measured at Thwaites and Pine Island, showing the importance of the Getz region in relation to the most rapidly changing glaciers in Antarctica.”
Thwaites and Pine Island are among the most threatened glaciers in Antarctica. Researchers on a trip to Thwaites last year drilled the floating portion of the glacier and recorded direct observations of warm seawater flowing underneath. David Holland, a glaciologist at New York University who conducted the research, saying in a press release at the time that “suggests that it may be experiencing an unstoppable retreat that has huge implications for global sea level rise.”
The new finds in the Getz region add another layer of concern. Antarctica has a major impact on sea level rise around the world, and understanding how ice behaves on the continent is becoming increasingly crucial in determining how much sea level rise we could expect. Additionally, collapsing ice shelves in the region behave like corks coming out of a wine bottle, releasing a torrent of ice into the sea and creating more instability and melting in the region. The Thwaites and Pine Island glaciers, for example, are the cork in land ice that, if dropped into the ocean, could push the seas. 10 feet (3.1 meters) or higher. Paying more attention to how little-studied areas like Getz are doing will be important in preparing for the future.
“If we don’t understand why the changes are happening, then we can’t accurately model the change,” Selley said. “This, in turn, means that we cannot reliably predict future ice loss and sea level contribution from Antarctica.”