atmospheric co2 

Atmospheric CO2 Data (2000years)

Atmospheric CO2 record based on ice core data before 1958, (Ethridge et. al., 1996; MacFarling Meure et al., 2006) and yearly averages of direct observations from Mauna Loa and the South Pole after and including 1958 (from Scripps CO2 Program).
source: http://scrippsco2.ucsd.edu/data/atmospheric_co2/icecore_merged_products