In July 2017 the massive iceberg later named A-68 embarked on an extraordinary four years voyage drifting from the Antarctic Sea ice to a distant island.
A massive iceberg named A-68 which separated from Antarctica Larsen-C Ice Shelf in 2017 created a unique marine habitat during its four years drift according to recent scientific studies. In July 2017 this iceberg broke away in a process called calving starting a journey across the Southern Ocean. At the time A-68 was the largest iceberg adrift spanning over 2200 square miles (about 5698 km) more than twice the size of Luxembourg. The iceberg gained worldwide attention as it moved north driven by ocean currents and winds.
In late 2020 concerns grew when A-68 approached South Georgia Island vital breeding area for vulnerable species. South Georgia is an incredibly rich dynamic marine ecosystem said Geraint Tarling polar ecologist at the British Antarctic Survey in Cambridge UK. The nutrient rich waters around the island support phytoplankton, krill and larger marine species while its shores serve as nesting grounds for threatened species such as king penguins and wandering albatrosses.
However A-68 avoided a damaging collision with the island. The iceberg began to disintegrate in December 2020 eventually breaking into smaller fragments and melting throughout 2021.
As it melted A-68 released billions of tons of freshwater into the ocean profoundly impacting the surrounding marine habitat. The iceberg fostered conditions that scientists observed to support diverse ecosystems acting as a temporary refuge for various species.
Nutrient levels in the nearby waters surged attracting ice associated algae and creating temporary vibrant micro ecosystems. Zooplankton gathered to feed on the algae and polar ecologist Geraint Tarling suggested that larger animals such as baleen whales might have followed.
There was this halo effect Tarling explained where algae bloomed around the iceberg fragments.
It was all happening so quickly it completely shifted the dynamics he added. The iceberg was releasing massive amounts of freshwater pushing down the layers beneath it causing conditions typical at 164 feet to instead occur at 328 feet.
Food particles drifting through the water were also forced deeper. This deepening of water masses has created an effect we’ve never seen before driving down particulate matter along with it Tarling noted.
This process may have actually increased the carbon sequestered on the seafloor of the Southern Ocean. Usually organic material descends slowly through the water with much of it consumed before reaching the seabed. However the enormous influx of freshwater from A-68 likely sped up the descent of carbon based particles to depths where they were less likely to be consumed.
No one ever documented this before said Tarling hinting that massive icebergs like A-68 could aid in driving carbon to ocean depths potentially lowering greenhouse gas levels in the atmosphere.
Throughout its journey after detaching from the Antarctic ice shelf A-68 lost a remarkable 802 billion tonnes of ice. Between late 2020 and early 2021 it released approximately 152 billion tonnes of freshwater into the ocean equivalent to nearly 61 million Olympic sized swimming pools.
