Massive iceberg on alarming collision course with marine life haven

The world’s largest iceberg, A68a, is currently on course to ground itself off the coast of sub-Antarctic island South Georgia, which could have some serious negative implications for local marine life including penguins and seals.

Satellite imagery shows A68a (shaped like a pointing finger at the bottom of the photo) on a collision course with South Georgia (the crescent shaped island at the top)

In 2017, A68a became the largest iceberg in the world’s oceans when it broke off from the Antarctic Peninsula. Ever since the massive iceberg, which is currently the size of Cyprus at around 2000 square miles (5,100km2), has been slowly edging its way north. Now satellite imagery from the British Antarctic Survey (BAS) shows it is on course to reach South Georgia, where it may become stuck on the island’s submarine shelves. If it does get stuck it could spell disaster for the local marine wildlife by majorly disrupts feeding routes of penguins, seals, seabirds and even whales. It is still touch and go as to whether or not this nightmare scenario will come to pass, but it highlights a potential new problem for islands across the South Atlantic as the Antarctic ice sheet continues to break apart.

Iceberg graveyard

The idea of icebergs getting stuck of the coast of sub-Antarctic islands is unfortunately nothing new. Over the last few decades it has become increasingly common for the huge chunks of ice to get caught on the submarine shelves surrounding islands like South Georgia. This happens because around 90% of icebergs are actually underwater, meaning they extend much deeper into the water column than most people imagine. For larger icebergs like A68a this means they can get stuck in waters as shallow as 100 to 200 metres. As more icebergs continue to break off from the Antarctic Peninsula, due to rising temperatures from global warming, this has become a more frequent occurrence. As a result the South Atlantic region has earned the nickname of the ‘iceberg graveyard’, which unfortunately is going to become even more relevant in the coming decades.

A68a breaks off from a 10,000 year old ice sheet in the Antarctic Peninsula

A 10 year stay

On its current trajectory A68a is likely to get caught on the submarine shelves surrounding South Georgia. Experts at BAS believe that if this does happen it could remain in the area for as long as a decade. This has the potential to be extremely devastating for the local marine life which relies on the island as a haven. There are hundreds of thousands of marine animals living on South Georgia including seabirds such as albatross, but most importantly seals and penguins who rely on the island as a breeding ground. The main worry researchers have is that A68a will impede these animals ability to feed of the coast, which could mean they fail to provide for their juvenile offspring as a result.

South Georgia is an important breeding ground for seal and penguin populations in the Southern Atlantic

The best reference we have for this type of disruption was a similar incident in the early 2000’s, when another massive iceberg B-15A struck parts of the Ross Islands and became stuck there for around four years. During this time penguin breeding failed for several years as the parents had to travel so much further afield to find food that their chicks would die from starvation before they returned. Given that A68a is larger than B-15A and could remain in South Georgia for over twice as long, the impacts on seals and penguins there may be even more severe. It could potentially mean they lose several generations of new recruits and put the entire populations at risk as a result. This could also have unforeseen knock-on consequences for other animals in the food chain such as whales and dolphins, who have only recently recovered from historically high levels of whaling in South Georgia.

Still some hope

Whilst things aren’t looking too good for the wildlife residents of South Georgia, there is still a chance that the island may escape its icy fate. A68a is moving at around one kilometre a day, which puts it on course to reach South Georgia within a month. However, despite currently being on course to hit the island according to satellite imagery, some researchers still aren’t totally convinced that it will. The southern ocean has some of the strongest currents in the world, so it could still significantly shift course over the next month. It is also unclear how deep into the water column A68a extends and given its size, it may actually get stuck before it gets too close to land, which would mean less of an impact on local marine life. There is also a chance that due to its size it may fracture under its own weight when it grounds, which could alter the impact it has on marine life in a much harder to predict way. Only time will tell if the worst case scenario does occur and A68a becomes a permanent fixture off the coast of South Georgia, but there is still a chance it might not.

Humpback whales have only recently returned to South Georgia after a 50 year absence, but how long will they be aloud to stay?

Big problem for the future?

As we are already seeing icebergs are starting to become a big problem for islands in the South Atlantic. For glaciologists like Dr M Jackson, a National Geographic explorer and author of ‘The Secret Lives of Glaciers’, it is a problem that only going to get worse in the coming decades. “I am doubtful given the increasing rate of ice melt worldwide that this is the last time we’ll see this,” she said whilst recently talking to the New York Times, “I wouldn’t be surprised in the years to come if we continue to see bigger icebergs presenting bigger hazards to communities of people and wildlife alike.” Her stark prediction highlights that as the effects of global warming continue to come into effect that there a number of new problems this will create for marine life and coastal human communities. Twenty years ago something like this would be almost unthinkable, but unfortunately it seems like just another issue we are going to have to start dealing with throughout the rest of this century.

The gigantic fracturing of A68a from the Antarctic as seen from a plane window. This is likely to become a much more common sight over the next few decades

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