Overview

• A23a now spans about 1,700 square kilometers and roughly 60 kilometers across, down from nearly 4,000 square kilometers earlier this year, according to satellite analyses.
• Scientists report the berg is shedding very large pieces, some around 400 square kilometers, as well as smaller fragments that pose navigation hazards and are being tracked by the U.S. National Ice Center.
• After calving in 1986 and sitting grounded in the Weddell Sea for decades, A23a freed in 2020, re-grounded near South Georgia in March 2025, then resumed a northward drift along the Southern Antarctic Circumpolar Current Front.
• British Antarctic Survey researchers visited the iceberg aboard the RRS Sir David Attenborough while it was grounded near South Georgia and recently returned samples to the UK to assess impacts on seafloor communities and surrounding waters.
• A23a has ceded the status of largest current iceberg to D15a at roughly 3,000 square kilometers, as BAS scientists highlight accelerated Antarctic ice-shelf losses linked to warmer oceans and shifting currents.