UK-led mission to study world’s biggest iceberg on collision course with South Georgia

Berg almost as large as Jamaica expected to have major effect on one of world’s most important ecosystems

A UK-led team of scientists will be sent to Antarctica to study the world’s largest iceberg, which is on a collision course with the sub-Antarctic island of South Georgia.

The iceberg, A-68a – a floating chunk roughly the size of Jamaica – is now less than 50km from the island.

Its arrival could spell disaster for much of the wildlife around South Georgia, one of the world’s most important ecosystems.

The island was a major whaling station until the mid-20th century, but now has no permanent human residents.

It is a major seal and penguin colony, and the iceberg is predicted to arrive during the animals’ breeding season.

The towering walls of ice, up to 38 metres (125 feet) high, combined with the extraordinary extent of the berg – 3,900 square kilometres – means that depending on exactly where it ends up, it could block animals from accessing the sea and finding food for their young.

Furthermore, the iceberg is likely to grind over the seabed, crushing the island’s underwater life.

This would not just be a temporary problem for the seals and penguins in the affected area. The British Antarctic Survey said the iceberg could remain lodged against the coast for up to 10 years before the ice finally melted and broke away.

It could prevent the island’s population of 2 million penguins – which includes king, gentoo, macaroni and chinstrap – from reaching the waters to feed their young.

The iceberg is composed of fresh water, which as it melts could also make the ocean inhospitable for phytoplankton and other sea creatures which are crucial parts of the food chain.

The A-68A iceberg South George island (via REUTERS)

The research mission will aim to determine the various impacts the A-68a iceberg will have, and gets under way next month.  

The scientists, led by the British Antarctic Survey, will set sail on the National Oceanography Centre’s (NOC) ship, following a proposal to NERC to fund an urgent mission south.  

Recent images captured from the air by the Ministry of Defence show the iceberg is breaking up. The team will investigate the impact of fresh water from the melting ice into a region of the ocean that sustains the penguins, seals and whales. These waters are also home to some of the most sustainably managed fisheries in the world.

Underwater robotic gliders will be deployed from the NOC research ship RRS James Cook, which will depart from the Falkland Islands and head for the iceberg in late January.

Oceanographer Dr Povl Abrahamsen, from the British Antarctic Survey, is leading the mission.

“We have a unique opportunity to visit the iceberg,” he said. “Normally, it takes years to plan the logistics for marine research cruises, but NERC, working with the government of South Georgia and the South Sandwich Islands and the UK government’s Blue Belt Programme, recognised the urgency to act quickly, allowing us to study the iceberg during an upcoming voyage to monitor the ecosystem and climate of the Southern Ocean.  

“Everyone is pulling out all the stops to make this happen.”

The two 1.5-metre untethered submersible gliders will spend almost four months collecting measurements of seawater salinity, temperature and chlorophyll from opposite sides of the iceberg, piloted over satellite link by personnel at NOC and the British Antarctic Survey.

The team will also measure how much plankton is in the water and compare its findings with long-term oceanographic and wildlife studies around South Georgia and nearby Bird Island.  

The British Antarctic survey said the waters around South Georgia were recognised as one of the most biologically rich places on the planet, with more described marine species than the Galapagos. The area is one of the world’s largest Marine Protected Areas.

A satellite image of the A-68A iceberg (via REUTERS)

Professor Geraint Tarling, an ecologist at the British Antarctic Survey, said: “The iceberg is going to cause devastation to the sea floor by scouring the seabed communities of sponges, brittle stars, worms and sea-urchins, so decreasing biodiversity. 

"These communities help store large amounts of carbon in their body tissue and surrounding sediment. Destruction by the iceberg will release this stored carbon back into the water and, potentially, the atmosphere, which would be a further negative impact.”

But Professor Tarling said that not all the impacts along the iceberg’s path were negative.

“For example, when travelling through the open ocean, icebergs shed enormous quantities of mineral dust that will fertilise the ocean plankton around them, and this will benefit them and cascade up the food chain,” he said.

The breakup of the edges of the ice and the smaller bergs which A-68a is shedding could pose threats to shipping. But the mission will also aim to keep tabs on dangerous bergs.

Andrew Fleming, head of remote sensing at the British Antarctic Survey, has been tracking the iceberg’s journey on images from the Copernicus Sentinel-1 and other satellites.

“We are watching the progress of the A-68a iceberg very closely as we haven’t seen a berg of this size in the area for some time,” he said. “As it breaks up, thousands of smaller icebergs have the possibility to obstruct shipping lanes in the area, especially as they disperse. The European Space Agency has delivered regular Sentinel-1 images and we will use these to continue tracking in the coming months.

“The images and footage collected by MoD flight missions have helped enormously in confirming some of the features we can see in the images from space. Close up images provide detail on how the berg is starting to break up and allow us to better understand these processes.”

Zac Goldsmith, minister for Pacific and the environment, said: “We need to understand the effects that huge icebergs can have on wildlife and marine life, so I’m delighted the Blue Belt Programme, which works with British Overseas Territories to protect and sustainably manage their waters, is able to support this critically important research mission.”