Three British explorers who endured frostbite, shifting ice and food shortages have described their feelings as mixed as they ended a research expedition in the Arctic.
They have been taking measurements of sea-ice thickness - primarily from drilling following the failure of a mobile radar unit - in a bid to help scientists better understand the changes taking place at the highest latitudes.
BBC environment correspondent David Shukman spoke to Pen Hadow, Ann Daniels and Martin Hartley about the expedition.
One-Minute World News 
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