Carbon dioxide levels hit landmark in Northern Hemisphere

Carbon dioxide levels hit landmark in Northern Hemisphere

Half the world sees full month at or above symbolic 400 parts per million CO2 level

By Beth Mole, 16:41 PM May 28, 2014

April was the first month in recorded history with average carbon dioxide levels at or above 400 parts per million across the Northern Hemisphere, according to a May 26 announcement by the World Meteorological Organization.

Climate scientists first recorded the troubling peak in the greenhouse gas in the Arctic in 2012 and in Hawaii last year (SN: 12/28/2013, p. 26), but the rest of the globe had yet to consistently hit the high mark. The 400 ppm level is largely symbolic, representing nearly ...

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