The world’s largest and oldest iceberg A23a has broken free after decades of being grounded on the seabed near Antarctica. This colossal “mega-berg,” weighing over a trillion tonnes and spanning an area twice the size of Greater London is now drifting into the Southern Ocean.
A23a was calved from Antarctica’s Filchner Ice Shelf in 1986, marking the beginning of its extraordinary journey. For over 30 years, it remained grounded on the seabed of the Weddell Sea. In 2020, it began to shift northward, but its progress was slowed by a Taylor Column, an oceanographic phenomenon that kept it spinning in one spot for months.
Dr. Andrew Meijers, an oceanographer at the British Antarctic Survey, remarked, “It’s exciting to see A23a on the move again after periods of being stuck. We are curious to see the route it takes and how it impacts the ecosystem as it drifts into new waters.”
The iceberg is now following the Antarctic Circumpolar Current, which is expected to steer it toward the sub-Antarctic island of South Georgia. Warmer waters in this region will likely cause the iceberg to fracture into smaller pieces and eventually melt.
While this may mark the end of A23a’s journey, its path could have significant ecological impacts. As icebergs melt, they release nutrients like iron into the surrounding waters, promoting phytoplankton growth and supporting marine ecosystems.
Last year, researchers aboard the British Antarctic Survey’s RRS Sir David Attenborough studied A23a during a mission in the Weddell Sea. Scientists collected water samples near the iceberg to understand how these massive icebergs influence ocean ecosystems and the global carbon cycle.
Laura Taylor, a biogeochemist involved in the study, noted, “We know giant icebergs can enrich waters with nutrients, creating thriving ecosystems in less productive areas. The data we collected will help us understand how A23a affects carbon balance in the ocean and atmosphere.”
The movement of A23a offers a unique opportunity for scientists to study how massive icebergs interact with their environments. Its journey serves as a reminder of the dynamic nature of Earth’s polar regions and their influence on global climate and ecosystems.
As A23a continues its voyage, researchers will monitor its progress and the cascading effects it may have on marine life and ocean chemistry.
