The world's largest iceberg has become stuck in shallow waters near South Georgia, a remote British island home to a vast number of penguins and seals. The iceberg, which is about twice the size of Greater London, appears to be immobile.
It will likely start breaking apart on the island's southwest shores. Fishermen are concerned that they will have to navigate around huge chunks of ice. This could also impact some macaroni penguins that feed in the area.
However, scientists in Antarctica believe that the ice contains large amounts of nutrients. As the iceberg melts, it could lead to an explosion of life in the ocean. Prof Nadine Johnston from the British Antarctic Survey compares it to "dropping a nutrient bomb into the middle of an empty desert."
Mark Belchier, an ecologist who advises the South Georgian government, warns that if the iceberg breaks up, the resulting icebergs could pose a hazard to vessels. They may move with local currents and restrict access to nearby fishing grounds. This stranding is the latest development in a nearly 40-year journey that began when a massive chunk of ice broke off the Filchner-Ronne Ice Shelf in 1986.
Satellite images had tracked its route since December when it finally broke free after being trapped in an ocean vortex. As it moved north through warmer waters known as Iceberg Alley, it remained surprisingly intact. For a brief period, it even seemed to spin in place before accelerating in mid-February, traveling at about 20 miles (30km) per day.
Prof Huw Griffiths, speaking to BBC News from the Sir David Attenborough polar research ship currently in Antarctica, expressed surprise at the iceberg's longevity. He noted that all icebergs eventually die, but A23a has lasted an exceptionally long time, losing only about a quarter of its area. On Saturday, the 300-meter-tall ice giant collided with the shallow continental shelf approximately 50 miles (80km) from land.
It now seems to be securely stuck in place. Prof Andrew Meijers from the British Antarctic Survey predicts that it will likely remain more or less where it is until pieces break off. The iceberg shows signs of advancing decay. Initially measuring 3,900 sq km (1,500 sq miles), it has been continuously shrinking, losing significant amounts of water as it enters warmer seas.
Its current estimated size is 3,234 sq km. Prof Meijers describes the changes, saying, "Instead of a big, sheer, pristine box of ice, you can see caverns under the edges." Tides will now lift the iceberg up and down. Where it touches the continental shelf, it will grind back and forth, eroding both the rock and ice.
Prof Meijers explains that if the ice underneath is rotten and eroded by salt, it will crumble under stress and potentially drift to shallower areas. However, where the ice touches the shelf, there are thousands of tiny creatures like coral, sea slugs, and sponges. Prof Griffiths describes their situation, saying, "Their entire universe is being bulldozed by a massive slab of ice scraping along the sea floor."
This is catastrophic in the short term for these species, but he emphasizes that it is a natural part of the region's life cycle. He adds, "Where it is destroying something in one place, it's providing nutrients and food in other places." There had been concerns for the islands' larger animals.
In 2004, an iceberg in the Ross Sea affected the breeding success of penguins, leading to an increase in deaths. However, experts now believe that most of South Georgia's birds and animals will avoid that fate. Peter Fretwell at the British Antarctic Survey suggests that some Macaroni penguins that forage on the shelf where the iceberg is stuck could be impacted.
The iceberg melts freshwater into saltwater, reducing the amount of food, including krill (a small crustacean), that penguins eat. He explains that the birds could move to other feeding grounds, but that would put them in competition with other creatures. The ice could block harbors or disrupt sailing when the fishing season begins in April.
Andrew Newman from Argos Froyanes acknowledges, "We will have to do battle with A23a for sure." Scientists currently working in Antarctica are also discovering the incredible contributions that icebergs make to ocean life. Prof Griffiths and Prof Johnston are working on the Sir David Attenborough ship, collecting evidence of what their team believes is a massive flow of nutrients from ice in Antarctica across the Earth.
The scientists explain that particles and nutrients from around the world get trapped in the ice, which is then slowly released into the ocean. Prof Griffiths emphasizes the importance of ice, stating, "Without ice, we wouldn't have these ecosystems. They are some of the most productive in the world, and support huge numbers of species and individual animals, and feed the biggest animals in the world like the blue whale."
A sign that this nutrient release has begun around A23a will be when vast phytoplankton blooms flourish around the iceberg. It would appear as a vast green halo around the ice, visible from satellite images over the coming weeks and months. The life cycle of icebergs is a natural process, but climate change is expected to create more icebergs as Antarctica warms and becomes more unstable.
More icebergs could break away from the continent's vast ice sheets and melt at faster rates, disrupting patterns of wildlife and fishing in the region.
It will likely start breaking apart on the island's southwest shores. Fishermen are concerned that they will have to navigate around huge chunks of ice. This could also impact some macaroni penguins that feed in the area.
However, scientists in Antarctica believe that the ice contains large amounts of nutrients. As the iceberg melts, it could lead to an explosion of life in the ocean. Prof Nadine Johnston from the British Antarctic Survey compares it to "dropping a nutrient bomb into the middle of an empty desert."
Mark Belchier, an ecologist who advises the South Georgian government, warns that if the iceberg breaks up, the resulting icebergs could pose a hazard to vessels. They may move with local currents and restrict access to nearby fishing grounds. This stranding is the latest development in a nearly 40-year journey that began when a massive chunk of ice broke off the Filchner-Ronne Ice Shelf in 1986.
Satellite images had tracked its route since December when it finally broke free after being trapped in an ocean vortex. As it moved north through warmer waters known as Iceberg Alley, it remained surprisingly intact. For a brief period, it even seemed to spin in place before accelerating in mid-February, traveling at about 20 miles (30km) per day.
Prof Huw Griffiths, speaking to BBC News from the Sir David Attenborough polar research ship currently in Antarctica, expressed surprise at the iceberg's longevity. He noted that all icebergs eventually die, but A23a has lasted an exceptionally long time, losing only about a quarter of its area. On Saturday, the 300-meter-tall ice giant collided with the shallow continental shelf approximately 50 miles (80km) from land.
It now seems to be securely stuck in place. Prof Andrew Meijers from the British Antarctic Survey predicts that it will likely remain more or less where it is until pieces break off. The iceberg shows signs of advancing decay. Initially measuring 3,900 sq km (1,500 sq miles), it has been continuously shrinking, losing significant amounts of water as it enters warmer seas.
Its current estimated size is 3,234 sq km. Prof Meijers describes the changes, saying, "Instead of a big, sheer, pristine box of ice, you can see caverns under the edges." Tides will now lift the iceberg up and down. Where it touches the continental shelf, it will grind back and forth, eroding both the rock and ice.
Prof Meijers explains that if the ice underneath is rotten and eroded by salt, it will crumble under stress and potentially drift to shallower areas. However, where the ice touches the shelf, there are thousands of tiny creatures like coral, sea slugs, and sponges. Prof Griffiths describes their situation, saying, "Their entire universe is being bulldozed by a massive slab of ice scraping along the sea floor."
This is catastrophic in the short term for these species, but he emphasizes that it is a natural part of the region's life cycle. He adds, "Where it is destroying something in one place, it's providing nutrients and food in other places." There had been concerns for the islands' larger animals.
In 2004, an iceberg in the Ross Sea affected the breeding success of penguins, leading to an increase in deaths. However, experts now believe that most of South Georgia's birds and animals will avoid that fate. Peter Fretwell at the British Antarctic Survey suggests that some Macaroni penguins that forage on the shelf where the iceberg is stuck could be impacted.
The iceberg melts freshwater into saltwater, reducing the amount of food, including krill (a small crustacean), that penguins eat. He explains that the birds could move to other feeding grounds, but that would put them in competition with other creatures. The ice could block harbors or disrupt sailing when the fishing season begins in April.
Andrew Newman from Argos Froyanes acknowledges, "We will have to do battle with A23a for sure." Scientists currently working in Antarctica are also discovering the incredible contributions that icebergs make to ocean life. Prof Griffiths and Prof Johnston are working on the Sir David Attenborough ship, collecting evidence of what their team believes is a massive flow of nutrients from ice in Antarctica across the Earth.
The scientists explain that particles and nutrients from around the world get trapped in the ice, which is then slowly released into the ocean. Prof Griffiths emphasizes the importance of ice, stating, "Without ice, we wouldn't have these ecosystems. They are some of the most productive in the world, and support huge numbers of species and individual animals, and feed the biggest animals in the world like the blue whale."
A sign that this nutrient release has begun around A23a will be when vast phytoplankton blooms flourish around the iceberg. It would appear as a vast green halo around the ice, visible from satellite images over the coming weeks and months. The life cycle of icebergs is a natural process, but climate change is expected to create more icebergs as Antarctica warms and becomes more unstable.
More icebergs could break away from the continent's vast ice sheets and melt at faster rates, disrupting patterns of wildlife and fishing in the region.
