Background atmospheric CO₂ mixing ratios from individual flask air samples for the South Pole. 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 South Pole, 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




1975    -99.99     -99.99   -99.99     -99.99   -99.99    -99.99    329.35   329.88   330.05     330.26   330.49    330.09   -99.99
1976    329.45     329.22   329.19     329.37   329.61    329.78    330.16   330.70   331.16     331.52   331.49    331.07   330.23
1977    330.82     330.67   330.48     330.49   330.65    330.95    331.56   332.50   332.98     332.79   332.49    332.38   331.56
1978    332.43     332.38   332.28     332.61   333.15    333.48    333.86   334.40   334.84     335.31   335.33    334.81   333.74
1979    334.63     334.60   334.47     334.62   335.02    335.24    335.70   336.32   336.38     336.40   336.45    336.19   335.50
1980    335.93     335.87   335.92     336.14   336.44    336.72    337.21   337.71   337.92     338.01   338.01    337.85   336.98
1981    337.65     337.58   337.63     337.84   338.13    338.41    338.90   339.31   339.29     339.24   339.30    339.11   338.53
1982    338.87     338.61   338.46     338.73   338.99    339.07    339.37   339.84   340.13     340.18   340.03    339.81   339.34
1983    339.66     339.53   339.54     339.99   340.43    340.65    341.01   341.52   341.81     341.84   341.83    341.71   340.79
1984    341.58     341.54   341.47     341.44   341.58    341.81    342.18   342.68   343.01     343.07   343.02    342.88   342.19
1985    342.81     342.91   342.84     342.82   343.11    343.39    343.85   344.40   344.58     344.63   344.63    344.51   343.71
1986    344.40     344.16   344.11     344.22   344.43    344.72    345.02   345.55   345.89     345.87   345.81    345.75   344.99
1987    345.71     345.71   345.79     345.96   346.15    346.59    347.11   347.60   348.02     348.20   348.25    348.26   346.95
1988    348.13     347.88   347.93     348.18   348.34    348.59    349.03   349.48   349.72     349.85   349.85    349.78   348.90
1989    349.85     349.81   349.76     349.85   349.97    350.21    350.68   351.15   351.34     351.51   351.81    351.62   350.63
1990    351.03     350.79   350.69     350.96   351.39    351.60    351.94   352.32   352.53     352.68   352.68    352.55   351.76
1991    352.50     352.30   352.25     352.56   352.67    352.89    353.42   353.76   353.83     353.78   353.76    353.76   353.12
1992    353.52     353.11   352.94     353.13   353.51    353.96    354.45   354.87   355.05     355.03   354.96    354.81   354.11
1993    354.51     354.23   354.05     353.98   354.10    354.43    354.89   355.30   355.46     355.46   355.34    355.18   354.74