Background atmospheric CO₂ mixing ratios from individual flask air samples for the Ascension Island. Only measurements satisfying the data selection criteria fro background measurements are plotted. Consecutive background measurements are joined by lines. Background measurements interrupted by non-background measurements are not joined by lines.

Monthly atmospheric CO2 mixing ratios for the Ascension Island expressed in parts per 
million (ppm) and reported in the Scripps Institution of Oceanography X93 manometric mole fraction scale.
Annual values were calculated by CDIAC for years with complete records.  Missing values are denoted by -99.99.



Year      Jan 	     Feb      Mar	April	  May	   June	     July      Aug     Sept	  Oct 	   Nov       Dec     Ann



1979    -99.99     -99.99   -99.99     -99.99   -99.99    -99.99    -99.99   337.59   337.41     337.25   337.84    338.38   -99.99
1980    338.23     337.94   337.91     338.37   338.78    339.39    339.69   339.68   339.39     338.98   338.74    338.80   338.83
1981    339.10     338.92   339.26     339.58   339.05    339.13    340.27   340.91   340.66     340.44   340.26    339.78   339.78
1982    339.72     339.87   340.00     340.72   341.09    340.81    340.92   341.44   341.36     341.17   340.86    340.62   340.72
1983    341.36     341.91   341.62     341.74   342.45    343.35    343.45   343.18   343.18     343.34   343.22    343.29   342.67
1984    343.29     342.57   342.42     342.74   343.43    344.18    345.06   345.22   344.29     344.54   344.96    344.21   343.91
1985    343.72     343.75   344.17     344.09   344.18    345.44    346.06   345.76   345.79     346.29   346.23    346.05   345.13
1986    345.87     345.06   344.34     344.81   345.62    346.20    347.05   347.41   346.97     346.77   346.94    346.69   346.14
1987    346.52     346.65   346.82     347.07   348.05    349.11    349.44   349.63   349.41     349.23   349.55    349.48   348.41
1988    349.24     349.37   349.30     349.10   349.58    350.81    351.50   351.29   351.16     351.13   351.16    351.25   350.41
1989    351.30     351.21   350.57     350.66   351.17    351.58    352.22   352.45   352.26     352.07   351.94    351.82   351.60
1990    351.83     351.67   351.18     351.80   352.69    353.01    353.68   354.26   354.00     353.91   353.88    353.39   352.94
1991    353.37     353.46   352.88     352.49   353.15    353.94    354.42   354.69   354.47     354.73   354.86    354.48   353.91
1992    354.23     354.10   354.02     354.52   355.16    355.49    356.09   356.14   355.84     355.82   355.64    355.19   355.19
1993    354.84     354.64   354.52     354.67   355.05    355.95    356.17   356.27   357.27     357.35   356.50    356.11   355.78