Every northern hemisphere monitoring station forming the World Meteorological Organization (WMO) Global Atmosphere Watch network reported record atmospheric CO2 concentrations during the seasonal maximum. This occurs early in the northern hemisphere spring before vegetation growth absorbs CO2.
CO2 levels first reached 400 ppm in April 2012, but this is the first time the monthly average passed the threshold. The agency predicts the global annual average CO2 concentration will cross this threshold in 2015 or 2016.
WMO Secretary-General Michel Jarraud said time to act is running out.
“This should serve as yet another wakeup call about the constantly rising levels of greenhouse gases which are driving climate change. If we are to preserve our planet for future generations, we need urgent action to curb new emissions of these heat trapping gases," he said.
CO2 was responsible for 85% of the increase in radiative forcing – the warming effect on our climate - over the decade 2002-12. Between 1990 and 2013 there was a 34% increase in radiative forcing because of greenhouse gases, according to the latest figures from the U.S. National Oceanic and Atmospheric Administration (NOAA).
According to WMO’s Greenhouse Gas Bulletin, the amount of CO2 in the atmosphere reached 393.1 parts per million in 2012, or 141% of the pre-industrial level of 278 parts per million. The amount of CO2 in the atmosphere has increased on average by 2 parts per million per year for the past decade.
Since 2012, all monitoring stations in the Arctic have recorded average monthly CO2 concentrations in spring above 400 ppm, according to data received from Global Atmosphere Watch stations in Canada, the US, Norway and Finland. This trend has now spread to observing stations at lower latitudes, including in Cape Verde, Germany, Ireland, Japan, Spain (Tenerife) and Switzerland.
The Intergovernmental Panel on Climate Change (IPCC) reported in April that to keep global mean temperature to two degrees Celsius, global greenhouse emissions must fall by 40-70% compared with 2010 by mid-century, and to near-zero by the end of this century.
UN Secretary-General Ban Ki-moon is convening a climate summit on September 23 with leaders from governments, businesses and civil society to raise the level of ambition and increase political momentum towards a global agreement.
