By AFP - Agence France Presse
Drifting mega-iceberg could threaten remote baby penguins
Nick Perry
The world's largest iceberg - a giant more than twice the size of London - is drifting towards a remote island where scientists say it could run aground and threaten baby penguins and seals.
The gigantic ice wall is moving slowly from Antarctica on a possible collision course with South Georgia, a crucial breeding ground for wildlife.
Satellite images suggest that unlike previous “mega bergs”, this rogue is not breaking up into smaller pieces as it advances across the Southern Ocean, Andrew Meijers, a physical oceanographer with the British Antarctic Survey, told AFP on Friday.
He said it was difficult to predict its exact course, but prevailing currents suggested the colossus would reach the shallow continental shelf around South Georgia in two to four weeks.
But what might happen next is unknown, he said.
It could avoid the shelf and be carried into open waters beyond South Georgia, a British overseas territory about 1,400 kilometers (870 miles) east of the Falkland Islands.
Or it could hit the sloping bottom and be trapped for months or break into pieces.
Meijers said that this scenario could seriously prevent seals and penguins from trying to feed and raise their young on the island.
“Icebergs have run aground there in the past and this has caused significant mortality of penguin chicks and seals,” he said.
- 'Whitewall'
Some 3,500 square kilometers (1,550 square miles) in diameter, the world's largest and oldest iceberg, known as A23a, emerged from the Antarctic shelf in 1986.
It remained trapped for more than 30 years before finally breaking free in 2020, its heavy journey north sometimes delayed by oceanic forces that kept it spinning in place.
Meijers - who encountered the iceberg face to face while leading a scientific mission in late 2023 - described “a huge white cliff, 40 or 50 meters high, stretching from horizon to horizon”.
“It's like a white wall. It's a lot like Game of Thrones,” he said, referring to the dark fantasy series. He described “the feeling that it would never end”.
A23a followed more or less the same path as previous massive icebergs, passing along the eastern side of the Antarctic Peninsula through the Weddell Sea on a route called “iceberg alley”.
Weighing just under a trillion tons, this monstrous block of fresh water was being dragged by the world's most powerful oceanic “jet stream” - the Antarctic Circumpolar Current.
Meijers said it was following “more or less a straight line from where it is now to South Georgia”, where the waters quickly become shallow and the current bends sharply.
The iceberg could follow this current out to sea or run aground on the shelf, he said.
Raul Cordero, from the University of Santiago in Chile, who is also part of the National Antarctic Research Committee, said he was confident that the iceberg would avoid South Georgia.
“The island acts as an obstacle to ocean currents and therefore usually diverts the water long before it reaches the island,” he said.
“The iceberg is moved by this flow of water, so the chances of it being hit are not that high,” although chunks could be hit, he said.
- Icy obstacle
It's summer in South Georgia and the resident penguins and seals along the south coast are foraging in the icy waters to fatten up their chicks.
“If the iceberg parks there, it will physically block the place they feed from or they will have to go around it,” said Meijers.
“This consumes a huge amount of extra energy for them, which means less energy for the pups and young, which causes increased mortality.”
The seal and penguin populations in South Georgia are already going through a “bad season” with an outbreak of bird flu “and this (the iceberg) would make things much worse,” he said.
“It would be quite tragic, but it's not unprecedented.”
When A23a melts, it could cover the ocean with small - but still dangerous - chunks of ice difficult for fishermen to navigate, Meijers added.
It would also seed the water with nutrients that would stimulate the growth of phytoplankton, feeding whales and other species and allowing scientists to study how these blooms absorb carbon dioxide from the atmosphere.
Although icebergs are very natural phenomena, Meijers said that the rate of loss of Antarctic icebergs is increasing, probably due to human-induced climate change.
np-mpr/gv/rlp
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