91Èȱ¬

Wildlife sound recordist Chris Watson first visited Antarctica in January 2010 and on his first morning, he was woken up by a howling blizzard.

It's the sound of arguably the most hostile environment on the planet. Whilst there, Chris was determined to record one of the greatest transitional events on the planet, the sounds of a glacier being transformed over the Antarctic summer from a solid mountain of freshwater ice into the salt water of the Ross Sea.

The place where he began recording was Cape Evans on Ross Island, by the hut 'Terra Nova' which was used by Captain Scott and his party during their ill-fated expedition to the South Pole in 1911.

The cinematographer Herbert Ponting who remained at Cape Evans later produced a film called ‘The Great White Silence. But this landscape is far from silent. West of 'Terra Nova', there is the Barne Glacier, a massive river of ice which flows down the slopes of Mount Erebus to the Ross Sea.

The recordings follow a journey beginnings inside the glacier with deep, powerful thumping sounds before it calves and huge blocks of ice crash onto the frozen sea. The sea ice buckles and cracks under the weight of these blocks producing extraordinary musical tones. Blocks of ice break off under pressure to form icebergs.

Then there's a gradual reduction as the sea ice undergoes its annual melt. Standing near a patch of open water Chris has an astonishing encounter with a minke whale which surfaces unexpectedly to breathe, and records Adelie penguins and the captivating scales of Weddell seals.

With the transformation complete, Chris watches and listens as Orcas break the surface of the waters to breathe in the air of the 'Great White Silence'.

Producer: Sarah Blunt

First broadcast on 91Èȱ¬ Radio 4 in 2015.