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A Delaware-sized iceberg headed for the sub-Antarctic island of South Georgia has worried experts about the possibility that it will block wildlife from food sources and threaten the island’s ecosystem.
The iceberg, known as the A68a, was about 400 kilometers, or about 250 miles, off the coast of the British island territory of South Georgia as of Wednesday, the British Antarctic Survey said.
The iceberg could run aground near the island and be a few weeks off the island’s coast, said Andrew Fleming, a remote sensing manager with the survey.
The iceberg broke off the Antarctic Peninsula in 2017 and is about 100 miles long and 30 miles wide. The trajectory of the iceberg could change and move away from the island, because it is in the strongest ocean current where the waters are not obstructed by the continents. This means that the iceberg could easily sail past the island, all depending on the path nature takes.
It’s unpredictable what could happen if the iceberg ran aground near South Georgia, said M Jackson, a glaciologist who is a National Geographic Society explorer. Such incidents are not unheard of, but more attention is usually paid to them when they pose a threat to people and wildlife, he said.
It is possible that if the A68a runs aground, it could disrupt part of the South Georgia ecosystem, affecting some of the areas and routes that animals, such as seals and penguins, travel to hunt and gather food.
“Basically, seals and penguins are born ashore, then commute back and forth in the ocean to get and return with food to feed their young,” said Dr. Jackson. “The iceberg could disrupt this process and seals and penguins may not be able to get and feed their pups and chicks on land, potentially leading to widespread hunger.”
Douglas R. MacAyeal, a professor of geophysical sciences at the University of Chicago who has studied the behavior of large icebergs, compared A68a to another large iceberg, B-15A.
In the 2000s, B-15A struck parts of Ross Island in the Ross Sea and other surrounding icebergs, disturbing the island’s penguin colonies. Some colonies have gone years without hatching chicks. The disturbance has led some penguins to interbreed with those of different colonies.
“This has led to a genetic advantage of exchanging genetic material from different, normally isolated cohorts,” said Dr. MacAyeal in an email. “In my opinion: if A68a were to encounter the island itself or the shoals around it, it would be spectacular for a few days but it would not lead to an ecosystem catastrophe.”
Some experts predict that the A68a will eventually break into large pieces due to strong currents.
“The Southern Ocean around South Georgia is an absolutely wild place with strong currents and storm surges that will ‘flex’ the iceberg at the top of the ground point, causing stress and fractures just like a ship,” said Dr. MacAyeal.
If the iceberg breaks near the island’s coast, there is a possibility that it could displace large amounts of seawater “that can flood coastal communities,” said Dr. Jackson.
This type of danger is something that experts have faced as climate change has led to ice melt and ice systems breaking up at significant rates.
“I’m doubtful given the growing rate of ice melt around the world that this is the last time we’ll see it,” said Dr. Jackson. “I wouldn’t be surprised in the years to come if we continue to see larger icebergs that pose greater risks to communities of people and wildlife.”
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