A23a: Biography of an iceberg

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 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 and to scientists who have seen A23a up close and followed its journey and its impact as it released a trillion tonnes of fresh water and nutrients into the marine environment.