A massive iceberg weighing 315 billion tons has broken away from the Amery Ice Shelf in Antarctica encompassing 1,636 square kilometers (245 square miles) of ice, the largest iceberg to calve from the continent in more than half a century. Dubbed “D-28” by the National Ocean and Atmospheric Administration (NOAA), it's about the size of Greater London or urban Sydney.
It sounds dramatic, but experts are quick to remind the public that such calving events are perfectly normal, and it's unlikely related to climate change.
Amery Ice Shelf drains about 16 percent of the East Antarctic Ice Sheet and deposits ice into the ocean through the “natural, cyclical process of iceberg calving – a process that can take decades to complete,” according to NASA Earth Observatory.
D-28 measures around 210 meters (690 feet) thick and contains an estimated 315 gross tonnage of ice, said glaciologist Professor Helen Fricker in a tweet. Fricker notes that this portion of the ice is not the affectionately named “Loose Tooth” – a section of Amery that appears to be hanging on by a thread – that some publications have reported but rather a larger piece of ice the size of the Isle of Skye to the west of it.
“It is like expecting a baby tooth to come out, and instead out comes a molar," she wrote.
This part of the iceberg shelf was first spotted by researchers in 2002 and those monitoring it have been anticipating the calving for years. It was originally thought that the iceberg would break off sometime between 2010 and 2015. Though it appears dramatic, the calving event is part of a “healthy ice shelf cycle.” Icebergs often break off from ice shelves, huge portions of floating ice that spreads out over the water, due to natural processes contingent on a number of variables that include the temperature of both the outside air and the glacier, density, thickness, and environmental factors that may provide pressure on the ice sheet.
“Glaciologists are not alarmed about most of these processes; they are examples of Antarctica simply doing what we know Antarctica has done for thousands of years,” wrote Fricker in an article for The Guardian in 2017. She adds that there is a potential link between climate changes and the Antarctic ice sheet and because of this, every crack or melt stream becomes news.
“The situation is a conundrum: we want people to be aware of Antarctica and concerned about what might happen there in the near future as climate changes,” she wrote. “But hyping research results to sound like climate change, when they are just improved understanding of natural behavior, is misleading.”
Real threats do face sea ice around the world every day. A NASA analysis published earlier this year found that Antarctica’s sea ice is experiencing a “precipitous decline” bringing total sea ice coverage to the lowest it has been in 40 years, melting an estimated six times faster than it was in 1979. Between 1992 and 2017, Antarctica has lost 3 trillion tonnes of ice that has contributed to a global sea-level rise of 8 millimeters over the last 25 years. Similar preliminary findings are seen at the opposite poll as well; measurements of Arctic sea ice at the end of this summer were recently found to be the second-lowest since modern record-keeping began in the 1970s.