BBC: The thickness of Arctic sea ice “plummeted” last winter, thinning by as much as 49 centimetres (1.6ft) in some regions, satellite data has revealed. A study by UK researchers showed that the ice thickness had been fairly constant for the previous five winters. The team from University College London added that the results provided the first definitive proof that the overall volume of Arctic ice was decreasing. The findings have been published in the journal Geophysical …