Penguins Spared After Mammoth Iceberg Splits Into Smaller Pieces
Scientists had feared for wildlife as the iceberg headed for remote South Georgia Island in the South Atlantic
By James HookwayFeb. 6, 2021 8:00 am ET
An iceberg that had been the world’s largest is now breaking into pieces close to the island of South Georgia in the South Atlantic.
Scientists had worried about the impact on the remote island’s wildlife if the berg had grounded on its continental shelf. Salinity levels and water levels would have caused sweeping changes to the ecosystem, while plants and animals on the sea bed might have been crushed if the berg—once the size of Jamaica—had been borne ashore by the strong South Atlantic currents.
Then there was the matter of the penguins.
Ecologists feared that the island’s huge colonies of king and gentoo penguins would have to make large detours to reach their usual hunting grounds, with potentially dire consequences for chicks waiting back onshore.
Near Miss
A huge iceberg came close to being swept into the island of South Georgia and its fragile habitat before breaking up in the strong currents of the South Atlantic.
Instead, more than three years after calving off Antarctica’s Larsen C Ice Shelf some 930 miles to the south, warmer waters and the torque of the currents have shattered the behemoth into a dozen pieces, now known as A68b, A68c, and so on under the U.S. National Ice Center’s naming system. They now appear set to drift north, where they might prove a bigger problem for humans.
“As it breaks up, thousands of smaller icebergs have the possibility to obstruct shipping lanes in the area, especially as they disperse,” said Andrew Fleming, head of remote sensing at the British Antarctic Survey, which has been tracking the A68a’s voyage north through images provided by the European Space Agency and flyovers by Britain’s Royal Air Force.
The biggest section, still called A68a, is 330 square miles, bigger than New York City, with several chunks nearly as large. The breakup of A68a means the largest iceberg is now A23a, which broke off from Antarctica in 1986 but has remained grounded on the sea floor.
A team from the British Antarctic Survey is on its way from the Falkland Islands to assess the impact of the icebergs on the marine ecology of the area and gain some insight into what can be expected if the Antarctic ice shelf calves off more giant bergs as global temperatures rise.
“Everyone is pulling out all the stops to make this happen,” said oceanographer and team leader Povl Abrahamsen, aboard the RRS James Cook, which will arrive at the icebergs in mid-February.
Navigating a pack of vast icebergs can be a dicey undertaking, however. Besides the bergs themselves—particularly the parts below the surface—there are waterfalls of melting ice and the prospect of more chunks breaking off, causing large waves. To mitigate the risk, the mission includes two underwater robotic gliders to take samples that will allow the team to get a better idea of what kind of impact such a large mass of icebergs is having on the ocean conditions off South Georgia, one of the most biologically rich places on the planet and one of the world’s largest Marine Protected Areas.
The biggest concern is how the melting bergs might disrupt the ocean’s food chain. An influx of cold fresh water could kill off microscopic marine organisms called phytoplankton, starving the krill that feed on them and depleting populations of fish, seals, penguins and whales.
The area is so plentiful in marine life that Norwegian whalers established a whaling station on South Georgia in the early 20th century, which has since been abandoned.
Today there are no permanent residents on the island, only a rotating team of ecologists and other scientists who track fishing stocks and other wildlife, including albatrosses and seals.
The island is becoming increasingly important, however, as a base from which to monitor the number of icebergs breaking off from the Antarctic ice sheet and drifting their way north to warmer waters.
While icebergs have always broken off, or calved, from the ice cap, the concern is that a warming climate will flatten it like a melting snow-cone, driving more ice to the edge of the continent, where it eventually snaps off.
In a study published earlier this week, two geophysicists from the University of Copenhagen in Denmark warned that climate change might cause ocean levels to rise faster than initially feared, increasing the flood risk to heavily populated coastal regions.
Aslak Grinsted and Jens Hesselbjerg Christensen sought out data going back several centuries and found that ocean levels could rise by more than a meter if global temperatures rise by 2 degrees Celsius, more than current projections adopted by the United Nations Intergovernmental Panel on Climate Change, and by half a meter if temperatures rise by just half a degree Celsius.
Write to James Hookway at james.hookway@wsj.com
