Lack of sea ice has forced hundreds of walrus to scale cliffs where they then plunge to their death.
The falling bodies of blubber and tusks can also crush walrus on the beach while possibly triggering a stampede.
All they know, Attenborough says, is that they need to join the other walruses and find food.
‘A walrus’ eyesight out of water is poor,’ Attenborough says.
‘But they can sense the others down below. As they get hungry, they need to return to the sea.
‘In their desperation to do so, hundreds fall from heights they should never have scaled.’