An iceberg roughly the size of Delaware heading for the sub-Antarctic island of South Georgia has worried experts that it could deter wildlife from food sources and threaten the island’s ecosystem.
The iceberg, known as the A68a, was about 400 kilometers off the coast of the British island area of South Georgia on Wednesday, the British Antarctic Survey said.
The iceberg could run aground near the island and lie a few weeks off the island’s coast, said Andrew Fleming, a remote sensing manager on the survey.
The iceberg broke off the Antarctic Peninsula in 2017 and is approximately 100 miles long and 30 miles wide. The iceberg’s trajectory could change and keep it away from the island as it is in the strongest ocean current where the water is not obstructed by continents. This means that the iceberg can easily drive past the island depending on the course nature takes.
It is unpredictable what could happen if the iceberg runs aground near South Georgia, said M Jackson, a glaciologist who is a researcher with the National Geographic Society. Such episodes are not uncommon, but they are usually given more attention when they pose a threat to humans and wildlife, she said.
There is a chance that A68a, if aground, could disrupt part of the South Georgian ecosystem and affect some of the areas and trails where animals like seals and penguins hunt and forage.
“Essentially, seals and penguins are born on land and then commute back and forth in the ocean for food and come back to feed their young,” said Dr. Jackson. “The iceberg could interfere with this, and seals and penguins may not be able to provide food to their pups and chicks on land, potentially leading to widespread starvation.”
Douglas R. MacAyeal, professor of geophysics at the University of Chicago who has studied the behavior of large icebergs, compared A68a to another large iceberg, B-15A.
In the 2000s, the B-15A struck parts of Ross Island in the Ross Sea, as well as the other icebergs that surrounded it, disrupting the island’s penguin colonies. Some colonies went years without hatching chicks. The disruption caused some penguins to crossbreed with those from different colonies.
“This resulted in a genetic advantage of exchanging genetic material from different, usually isolated, cohorts,” said Dr. MacAyeal in an email. “In my opinion, if A68a hit the island itself or the swarms around it, it would be spectacular for a few days, but it would not lead to an ecosystem disaster.”
Some experts predict that due to strong currents, A68a will eventually crumble into large pieces.
“The Southern Ocean around South Georgia is an extremely wild place with strong currents and swell that” bends “the iceberg on the grounding point and loads and breaks it like a ship,” said Dr. MacAyeal.
If the iceberg breaks near the island’s coast, there is a chance it will displace large amounts of seawater that “can flood coastal communities,” said Dr. Jackson.
This type of danger has had to be addressed by experts as climate change has caused ice to melt and ice systems to break at significant rates.
“With ice melting around the world, I am doubtful that this will be the last time we will see this,” said Dr. Jackson. “I wouldn’t be surprised in the years to come if we continued to see bigger icebergs that pose greater threats to human and wildlife communities.”