A23a: Biography of an iceberg

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Forty years ago, an iceberg broke away from the Antarctic ice shelf. But this was no ordinary iceberg. A colossal chunk of ice which covered an area twice the size of London, it was as deep as the Empire State building is high and it weighed a trillion tonnes. For nearly four decades A23a was the world’s largest iceberg. Glaciologist Dr Catherine Walker was born in the same year that A23a began its journey so she has had a long professional and personal interest in this gigantic berg. She tells the story of A23a from its origins, its ice being laid down deep in the Antarctic over millennia, through to its final chapter shrinking, melting and feeding the ocean from which it came. Catherine talks to glaciologists who study the vast cracks which propagate across the Antarctic ice shelf to create a megaberg like A23a. She hears from scientists who have seen A23a up close, who have followed its journey and looked at its impact as it released a trillion tonnes of fresh water and nutrients into the marine environment. Underlying the story of this megaberg is the Antarctic’s vital role in regulating climate change and sea level rise – and how that role is faltering and failing as the ice retreats. (Photo: The A23a megaberg rising up from the grey waves of the sea against a dark grey sky. Credit: Chris Walton/British Antarctic Survey) Presenter: Dr. Catherine Walker Producer: Jeremy Grange Executive producer: Olivia Humphreys An Overcoat Media production for the BBC World Service