A Delaware-sized iceberg that broke off Antarctica’s Larsen C Ice Shelf in 2017 is on a potential collision course with Britain’s South Georgia Island, home to multiple species of penguins, seals, seabirds and blue whales that feed just offshore.
Satellite imagery shows the iceberg, shaped like a finger pointed in its direction of travel, headed toward South Georgia Island. It measures about 95 miles in length and 30 miles in width, making it roughly equivalent to the size of the island itself. It is now located less than 300 miles from the island, NASA found.
According to David Long, a Brigham Young University professor who tracks polar ice using satellite imagery, the iceberg is sizable enough that if it becomes grounded in shallow waters off the island’s eastern shore, it could make it difficult for native wildlife to forage for food.
Geraint Tarling, an ecologist at the British Antarctic Survey, said in a news release that the iceberg could have “massive implications” for local species, especially if it is there for a long time.
“When you’re talking about penguins and seals during the period that’s really crucial to them — during pup and chick-rearing — the actual distance they have to travel to find food [fish and krill] really matters,” Tarling said. “If they have to do a big detour, it means they’re not going to get back to their young in time to prevent them starving to death in the interim.”
According to Long, an iceberg following a similar path in the 2000s ran aground on the east side of South Georgia Island and remained in place for a year and a half. The incoming slab of ice is also following a route similar to one that Ernest Shackleton followed when he sailed between Elephant Island and South Georgia Island in the early 20th century.
Stanley Jacobs, an ocean and climate researcher at Columbia University’s Lamont-Doherty Earth Observatory, said it is unlikely the iceberg will collide directly with the island.
“It could depend on currents and winds at the time, but most 'bergs slip by to the south of South Georgia Island, then often loop toward the north for a while before continuing eastward,” Jacobs said in an email. “If the 'berg comes close, it could run aground on a relatively wide shelf around the island.”
Most icebergs calving off ice shelves and glaciers in Antarctica are swept from the Weddell Sea into the South Atlantic Ocean, as A-68A has been, Long said. But A-68A has the distinction of being a consequence of human-caused climate change.
“The calving of A-68A is directly related to global warming,” Long said.
The Antarctic Peninsula, where the Larsen C Ice Shelf is located, is one of the fastest-warming areas in the world. In February, a temperature of nearly 70 degrees was recorded on Seymour Island in the Antarctic Peninsula, which may be the continent’s highest temperature on record.
As the ice shelves like Larsen C melt, they free up inland ice to move into the ocean, raising sea levels. Many other parts of the Antarctic Ice Sheet are also showing disturbing signs of instability.
For example, the Pine Island Glacier is melting, shedding icebergs as it does so. An international scientific effort is underway to better understand the fate of Pine Island and Thwaites Glaciers which already constitute about 5 percent of global sea level rise.
Should Thwaites be lost, it could cause the West Antarctic Ice Sheet to slide into the sea, raising global average sea levels by about 10 feet.