Guardian: The Arctic Ocean occupies just 3% of the Earth’s surface. It is the smallest and shallowest of the oceans, made up of two basins separated by the Lomonosov ridge. The expanding and contracting veneer of floating sea ice that it supports makes it a unique habitat – and one that is threatened because the Arctic is warming at twice the global average. Take away the sea ice and it is hard to see how walruses, polar bears and ringed seals will survive. But apart from these icons of the …