Study shows Arctic ice thinning is irreversible since 2007.

Arctic sea ice has been in a "new regime" since 2007, with a trend towards ice cover that is much thinner and younger than it had been before, according to a study by the Norwegian Polar Institute. The change is linked to rising ocean temperatures in the rapidly warming Arctic, driven by human emissions of greenhouse gases. The researchers suggest the loss of ice is a fundamental change unlikely to be reversed this century, if ever, and could be proof of a climactic tipping point that scientists have warned the planet could pass as it warms.