a. Manmade global warming
b. Natural swings
c. Both of the above
d. Neither of the above
ANSWER: Both of the above
Explanation:
Natural swings in the Arctic climate have caused up to half the precipitous losses of sea ice around the North Pole in recent decades.
However the rest was driven by man-made global warming as per a study.
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.
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, rivalling 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.
The findings could help narrow down huge uncertainties about when the ice will vanish.
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