Study: Arctic ice melting 'unprecedented'

Arctic sea ice has declined at an unprecedented rate during the past 50 years, a study in the British journal Nature said. The study, published online Wednesday, said both the duration and magnitude of the current decline in sea ice "seem to be unprecedented for the past 1,450 years." By analyzing sea ice for chemicals such as salt and methanesulfonic acid and comparing findings to other data such as sediment cores and tree rings, the researchers were able to reconstruct the amount of sea ice across the Arctic in the past, the Canadian Broadcast Corp. reported Wednesday. Christophe Kinnard, lead author of the report, said a number of different issues are driving the loss of sea ice. "Everything is trending up -- surface temperature, the atmosphere is warming, and it seems also that the ocean is warming and there is more warm and saline water that makes it into the Arctic," the CBC quoted Kinnard said saying, "and so the sea ice is eroded from below and melting from the top." Previously, sea ice loss was driven by changes in ocean currents and not necessarily by periods of warmer temperatures.