The 2012 average annual concentration of CO2 in the atmosphere (Mauna Loa Observatory) is 393.84 parts per million (ppm). The 2011 average is 391.65 ppm.
6th December 2011 Delaying any decisions on future climate action until 2015 or 2020 will bring a rapidly increasing risk in costs and threatens the likelihood of the world being able to keep global warming to below 2 degrees C, the Climate Action Tracker warned today in its Durban update.