The current record holder for the world’s biggest iceberg is the A23a. Back in 1986 this colossus broke away from an Antarctic ice sheet. This process of breaking off or ‘calving’ as it is known is a natural part of the life cycle of an ice sheet. But A23a then became lodged in the Weddell Sea for more than thirty years, until four years ago a gradual melting allowed the berg to refloat.

Since then it’s been steadily on the move, heading in the same direction as Antarctic icebergs before it, towards the warm waters of the Southern Ocean, where it will eventually shrink from melting.

As it travels, the iceberg has been playing an important role on the ecological environment around it, both in positive and negative ways.

Contributors:

Presenter: William Crawley

Image Credit: A23a in Antarctica, Jan 2024. Rob Suisted/Reuters/via BBC Images