Atmospheric CO2: January 1959 to January 2015
Mauna Loa Observatory – Scripps Institution of Oceanography
Source: CO2Now

Keeping Track of the Earth’s Atmospheric CO2

“If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced … to at most 350 ppm.”
~ Dr. James Hansen, former NASA Climatologist