In July 2017, a massive iceberg named A-68 broke free from Antarctica’s Larsen C Ice Shelf in an event known as “calving,” launching a four-year journey across the Southern Ocean. Covering an area of over 2,200 square miles (5,698 square kilometers) more than twice the size of Luxembourg A-68 became the world’s largest iceberg adrift, capturing attention as it drifted north.
As it traveled, A-68 encountered a critical breeding ground for threatened marine species near South Georgia Island, raising concerns. Geraint Tarling, a polar ecologist at the British Antarctic Survey, highlighted the rich marine ecosystem surrounding South Georgia, teeming with phytoplankton, krill, king penguins, and wandering albatrosses. Fortunately, A-68 narrowly avoided a direct collision with the island but began to break apart in late 2020, gradually melting and releasing billions of tons of freshwater into the ocean.
The melting iceberg created conditions that temporarily supported diverse ecosystems. As A-68 broke down, it released freshwater that increased nutrient levels, attracting algae and zooplankton and establishing a temporary “halo” of life. This environment likely drew larger animals, including baleen whales, creating a unique ecosystem surrounding the iceberg fragments.
The influx of freshwater also altered water dynamics by pushing deeper layers downward, forcing food particles and nutrients to sink faster. This accelerated descent could have increased carbon burial in the ocean’s depths, where it’s less likely to be consumed and more likely to remain sequestered, potentially reducing greenhouse gas concentrations in the atmosphere.
Throughout its journey, A-68 shed around 802 billion tonnes of ice. In its final stage between 2020 and 2021, it released about 152 billion tonnes of freshwater equivalent to nearly 61 million Olympic-sized pools reshaping not only marine ecosystems but also contributing to the global understanding of icebergs’ potential climate impact