Will a massive iceberg end up striking South Georgia island? Scientists unsure but tracking A68a’s movement
Iceberg A68a made headlines in July 2017 when the block, which NASA estimates to be roughly the size of Delaware, broke from the Larsen C ice shelf on the Antarctic Peninsula. Believed to be the world’s largest, the berg is back in the spotlight as it is now drifting toward South Georgia, a remote island in the southern Atlantic Ocean. Scientists fear that if it becomes grounded near the island or hits it, it has the potential to cause major damage by disrupting the local wildlife that forages in the food-rich ocean. The South Georgia and South Sandwich Islands marine protected area is one of the world’s largest marine protected areas, covering 1.24 million square kilometers.
Images of A68a were released recently following a reconnaissance flight of the iceberg. Currently traveling through the Southern Antarctic Front, it remains on course towards the island of South Georgia. Professor Geraint Tarling, an ecologist at British Antarctic Survey (BAS), told Reuters, “It is really, really close, less than 50 kilometers away.”
The massive size of A68a meant it was impossible to capture its entirety in one single shot. But this reconnaissance has provided “close up” imagery of the iceberg and surrounding waters for observers and experts to study. The aircraft was able to observe with unprecedented detail cracks and fissures within the main body of the iceberg. The data collected has been shared with both the Government of South Georgia & the South Sandwich Islands (GSGSSI) and the BAS, who are following the progress of the A68a. The imagery stills, video footage, and visual observations will all assist in predicting the iceberg’s future behavior and ascertaining the scale of the threat to the local area, explain officials.
We are keeping a close eye on the A68a iceberg as it drifts through #SouthGeorgia waters. These shots taken from a @RoyalAirForce A400M aircraft provide a unique view. It was so huge it was impossible to capture its entirety in a single shot! #SGSSIdiscover pic.twitter.com/nX8ToUfQP9
— Government SGSSI (@GovSGSSI) December 5, 2020
Between July 10 and July 12, 2017, the iceberg split off from Antarctica’s Larsen C ice shelf, says NASA. In just over three years at sea, A68a has moved generally northward, and it now continues to move toward South Georgia. Experts have pointed to a possible collision with the island, or that the iceberg could become stuck, or grounded in the shallow waters surrounding it. Either outcome could spell trouble for the island’s wildlife if the berg blocks the foraging routes of penguins and seals.
“Whether it grounds and gets stuck or drifts past the island is in the balance. The currents should take it on what looks like a strange loop around the south end of South Georgia, before then spinning it along the edge of the continental shelf and back off to the northwest. But it’s very difficult to say precisely what will happen,” notes BAS remote-sensing and mapping specialist Dr Peter Fretwell.
According to Tarling, ecosystems can and will bounce back, but there is a danger here that if this iceberg gets stuck, it could be there for 10 years. “An iceberg has massive implications for where land-based predators might be able to forage. When you’re talking about penguins and seals during the period that’s really crucial to them – during pup- and chick-rearing – the actual distance they have to travel to find food (fish and krill) really matters. If they have to do a big detour, it means they’re not going to get back to their young in time to prevent them starving to death in the interim,” he explains.
However, it could even have a positive impact. “The iceberg does bring benefits if it remains in the open ocean. It carries enormous quantities of dust that fertilize the ocean plankton in the water that cascades up the food chain. This plankton also draws in carbon from the atmosphere, partially offsetting human carbon dioxide emissions,” says Tarling.
The iceberg could still change path or break up significantly. “A68a is spectacular. The idea that it is still in one large piece is actually remarkable, particularly given the huge fractures you see running through it in the radar imagery. I’d fully expected it to have broken apart by now. If it spins around South Georgia and heads on northwards, it should start breaking up. It will very quickly get into warmer waters, and wave action especially will start killing it off,” emphasizes Andrew Fleming, BAS remote sensing manager.