The world’s largest iceberg, A23a, has begun drifting again through the Southern Ocean, after spending several months spinning in place, according to scientists from the British Antarctic Survey (BAS). Spanning 3,672 square kilometers (1,418 square miles) as of August, the iceberg is slightly larger than Rhode Island. Since its calving from the Filchner-Ronne ice shelf in 1986, A23a has been under close observation by researchers.
For more than three decades, A23a remained grounded on the Weddell Sea floor in Antarctica. Scientists believe that the iceberg remained stuck due to its size, but it eventually shrank enough to loosen its hold on the seafloor. Once free, ocean currents carried it away, but it became trapped once again in a Taylor column, a phenomenon where ocean currents create a vortex around an underwater mountain. This swirling vortex held A23a in place until recently.
Now that the iceberg has broken free, scientists expect it will continue drifting toward warmer waters and the remote South Georgia Island. There, A23a is expected to eventually break up and melt. BAS explained in a statement on Friday that the iceberg’s movement will be monitored as it continues its journey through the Southern Ocean.
Since the 1980s, A23a has been the largest current iceberg several times, although other larger icebergs such as A68 in 2017 and A76 in 2021 have temporarily surpassed it in size. However, these larger icebergs had shorter lifespans, and A23a reclaimed its title as the largest iceberg again after their breakup.
While the calving of A23a was likely a part of the natural cycle of the ice shelf’s growth and won’t directly contribute to rising sea levels, climate change is accelerating changes in Antarctica. These shifts have the potential to lead to significant increases in global sea levels. Scientists have pointed out that, in addition to its size, A23a’s journey has been an important opportunity to study the ways in which sea ice affects oceanic processes and the Earth’s carbon balance.
Over the years, researchers have closely examined the iceberg’s erosion and the impact it has on local ecosystems. Laura Taylor, a biogeochemist from BAS, highlighted that large icebergs like A23a can influence ocean ecosystems by introducing nutrients to waters they pass through, which can support thriving ecosystems in otherwise low-productivity regions.
“We know that these giant icebergs can provide nutrients to the waters they pass through, creating thriving ecosystems in otherwise less productive areas,” Taylor said in the BAS statement. However, she also pointed out that scientists do not yet fully understand the influence that specific icebergs, including their size and origins, have on these processes.
During A23a’s journey, scientists have taken samples from the ocean at different points along its path. These samples, which were collected from the surface waters both behind and ahead of the iceberg, will help researchers understand the role the iceberg plays in stimulating life in the surrounding waters and its effect on the ocean’s carbon dynamics. The samples will also offer insights into how the iceberg might influence the balance of carbon between the ocean and the atmosphere.
“What we don’t know is what difference particular icebergs, their scale, and their origins can make to that process,” Taylor added. The ongoing study of A23a’s journey will continue to provide valuable data on how large icebergs contribute to global ocean cycles of carbon and nutrients.
In the broader context of climate change, A23a’s movement through the Southern Ocean serves as a reminder of the rapidly changing dynamics in Antarctica and the potential long-term impacts on sea level rise. Scientists remain vigilant in tracking the iceberg’s path, as it moves closer to warmer waters, where it is likely to break up and eventually melt.
The movement of icebergs like A23a provides an opportunity to study the broader environmental effects of melting ice in the Southern Ocean. As researchers continue to monitor the iceberg’s journey, the findings could offer crucial insights into the effects of climate change on marine ecosystems and global carbon cycles.
While A23a’s natural detachment from the Filchner-Ronne ice shelf was part of the expected growth cycle of the ice shelf, the acceleration of such events due to climate change raises important concerns. Rising temperatures in the region could lead to more frequent calving events, contributing to higher sea levels and more significant disruptions to ecosystems.
Scientists will continue to analyze the data collected from the area around A23a, especially as it approaches warmer waters. As the iceberg breaks apart and melts, researchers hope to gain a clearer understanding of how these giant ice structures interact with the environment and influence the world’s oceans. These studies could ultimately help improve predictions about the future of Antarctica’s ice shelves and their contribution to global sea level rise.
The A23a iceberg’s current journey through the Southern Ocean offers an opportunity to learn more about the complex interactions between large icebergs, ocean ecosystems, and the global climate system. As A23a drifts toward warmer waters and eventually melts, scientists will continue to monitor the iceberg’s impact on the surrounding environment, providing critical information about the potential consequences of climate change for both local and global ecosystems.