Alister Doyle, reporting for Reuters: 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. The study indicates that an ice-free Arctic Ocean, often feared to be just years away, in one of the starkest signs of man-made global warming, could be delayed if nature swings back to a cooler mode. Natural variations in the Arctic climate “may be responsible for about 30-50 percent 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 ice is now around the smallest for mid-March, rivaling winter lows set in 2016 and 2015. 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.
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