Natural swings in the Arctic climate have caused up to half the precipitous losses of sea ice around the North Pole in recent decades, with the rest driven by man-made global warming, scientists said on Monday. Natural variations in the Arctic climate "may be responsible for about 30-50 per cent of the overall decline in September sea ice since 1979," the U.S.-based team of scientists wrote in the journal Nature Climate Change. Sea ice has shrunk steadily and hit a record low in September 2012 — late summer in the Arctic — in satellite records dating back to 1979. The study, separating man-made from natural influences in the Arctic atmospheric circulation, said that a decades-long natural warming of the Arctic climate might be tied to shifts as far away as the tropical Pacific Ocean. In 2013, a U.N. panel of climate scientists merely said human influences had "very likely contributed" to the loss of Arctic ice, without estimating how much.

Source: CBC News March 14, 2017 21:22 UTC