A BBC News team is heading to the Arctic to meet three polar explorers as they finish their gruelling trek across the ice-cap.
Pen Hadow, Ann Daniels and Martin Hartley have been taking measurements of sea-ice thickness in a bid to help scientists better understand the changes taking place at the highest latitudes.
On his way to meet the trio, BBC environment correspondent David Shukman stopped off at Resolute in the Canadian Arctic and travelled by snow mobile to edge of the frozen ocean.
One-Minute World News 
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