BBC: Changes in the Arctic Ocean are so profound that the region is entering what amounts to "a new era", according to Norwegian scientists.
A switch from a permanent cover of thick ice to a new state where thinner ice vanishes in the summer will have far-reaching implications, they say.
The Norwegian Polar Institute has been mounting an expedition to the Arctic Ocean during the year's coldest months.
Scientists have to brave extreme temperatures and total darkness.
Their aim is to gather...