Iceberg A-68a on collision course with South Georgia | Polarjournal
Cartographers from the British Antarctic Survey are tracking the iceberg’s route by satellite. (Photo: BAS)

A research mission will be launched in January 2021 to determine the impact of the giant A-68a iceberg on South Georgia. The island in the South Atlantic is one of the most important ecosystems in the world. A team of scientists led by the British Antarctic Survey (BAS) will set off towards the sub-Antarctic island on the National Oceanography Centre (NOC) ship for this purpose. This is according to a press release from BAS.

The satellite image taken on December 13, 2020 shows that the giant iceberg is 140 km long and is still about 75 km from South Georgia. (Photo: Copernicus Sentinel-1)

The giant iceberg that broke off from the Larsen C Ice Shelf in Antarctica in 2017 is currently 3,900 square kilometers in size. After satellite images revealed its path towards South Georgia, the science team submitted an application to NERC (Natural Environment Research Council) to fund an urgent mission to the south. Recent images taken from the air by the Department of Defense show that the iceberg is breaking up. Already, a corner of the colossus measuring almost 150 square kilometres has broken off and is now listed as a new iceberg named A68d. The team will study the impact of freshwater from melting ice on the region of the ocean that hosts colonies of penguins, seals and whales. These waters are also home to some of the most sustainably managed fisheries in the world.

Lord Zak Goldsmith, Minister for the Pacific and Environment, “We need to understand the impact that giant icebergs can have on wildlife and marine life, so I’m delighted that the ‘Blue Belt Programme’, which works with the UK Overseas Territories to protect and sustainably manage their waters, will support this important research mission.”

Oceanographer Dr. Povl Abrahamsen of the British Antarctic Survey is leading the mission. He says: “We have a unique opportunity to visit the iceberg. It usually 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 British government’s Blue Belt program, recognized the urgency to act quickly. This will allow us to study the iceberg during an upcoming expedition to monitor the ecosystem and climate of the Southern Ocean.”

The mission will take place on the National Oceanography Centre ship “RRS James Cook”. (Photo: NOC)

Diving robots are used for measurements

The two 1.5-meter-long submersible robots will spend nearly four months collecting measurements of salinity, temperature and chlorophyll in the seawater from opposite sides of the iceberg, controlled via a satellite link by NOC and BAS staff. The team will also measure how much plankton is in the water and compare their results with long-term oceanographic and wildlife studies around South Georgia.

Scientists will use two Slocum gliders to collect data from the A68a iceberg. (Photo: David White)

The waters around South Georgia are considered one of the most biologically rich places on the planet, with more described marine species than the Galapagos Islands, and are one of the largest marine protected areas in the world. The iceberg, if it runs aground near the island, poses a danger to penguins and seals during the breeding season, at least according to experts.

The iceberg A68a can cause massive damage

The iceberg can devastate the seafloor by eroding the communities of sponges, brittle stars, worms and sea urchins, reducing biodiversity. These communities help store large amounts of carbon in their body tissues and the surrounding sediment. Destruction by the iceberg will release this stored carbon back into the water and possibly the atmosphere, which would be another negative impact.

According to Professor Geraint Tarling, an ecologist with BAS, “However, while we are interested in the impacts of A-68a’s arrival in South Georgia, not all of the impacts along its path are negative. For example, icebergs lose enormous amounts of mineral dust as they travel through the open ocean, which fertilizes the plankton around them and promotes their growth.”

Steve Woodward, NOC’s technical manager for robotic diving, who will lead the operation of the National Marine Equipment Pool (NMEP), says: “Autonomous underwater gliders are an excellent, cost-effective and sustainable means of collecting and recording important marine data. In this case, we’ll program the NMEP submersible robots to get as close to the edge of the iceberg as we think is safe and practical, and collect the data needed so the team can understand the implications of what’s happening with A-68a.”

The extent of the damage to the penguin colonies on South Georgia is difficult to estimate at this time. The big colonies like Saint Andrews Bay are on the opposite side of the island. (Foto: Heiner Kubny)

Dr Mark Belchier, Director of Fisheries and Environment at the Government of South Georgia and the South Sandwich Islands (SGSSI), says: “With such events predicted to become increasingly common, understanding their impact on the SGSSI ecosystem is critical to the government’s sustainable management of the territory.”

Heiner Kubny, PolarJournal / British Antarctic Survey

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