Carbon dioxide levels hit landmark in Northern Hemisphere

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

SPEWING GAS Burning fossil fuels spews carbon dioxide into the atmosphere. In April, CO₂ levels reached a monthlong record of 400 parts per million across the Northern Hemisphere.

EpicStockMedia/Shutterstock

By Beth Mole

May 28, 2014 at 4:52 pm

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 150 percent of the CO₂ levels of pre-industrial times.

Although scientists expect CO₂ levels to continue rising, the Northern Hemisphere’s monthlong record for the greenhouse gas should sound an alarm for addressing emissions and climate change, the World Meteorological Organization said. From 2002 to 2012, CO₂ was responsible for 85 percent of the increase in the atmosphere’s heat-trapping ability.

Researchers expect the entire Earth will experience CO₂ levels averaging 400 ppm or higher in 2015 or 2016.