Monthly CO2 Mixing Ratios

Monthly atmospheric CO₂ mixing ratios from Mauna Loa, Hawaii, U.S.

Background atmospheric CO₂ mixing ratios from individual flask air samples for Mauna Loa, Hawaii, U.S. 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 Mauna Loa, Hawaii, U.S., 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

1969 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 322.95 321.37 320.71 322.01 323.77 -99.99 1970 325.13 325.54 325.67 326.59 327.68 327.28 326.12 324.91 322.96 322.54 323.83 325.27 325.29 1971 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 1972 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 1973 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 1974 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 1975 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 1976 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 332.39 330.96 329.71 329.33 330.58 332.05 -99.99 1977 332.80 333.14 333.99 335.69 336.49 336.00 334.71 332.32 330.96 331.36 331.98 333.57 333.58 1978 335.25 335.81 336.76 337.78 337.98 337.52 335.97 333.94 332.25 332.26 333.19 334.52 335.27 1979 336.04 337.01 338.42 338.99 338.90 338.95 337.62 335.42 333.90 334.04 335.09 336.40 336.73 1980 338.13 339.74 341.35 342.41 342.21 340.95 338.96 336.97 336.15 336.10 337.11 338.65 339.06 1981 340.05 341.41 342.33 343.21 343.38 341.99 340.28 338.57 337.21 337.38 338.86 340.03 340.39 1982 340.92 342.01 343.06 343.82 343.79 342.92 341.49 339.03 337.27 337.49 338.97 340.44 340.93 1983 341.74 342.18 342.84 344.85 345.85 345.08 343.29 340.95 339.58 339.73 340.85 342.47 342.45 1984 343.84 344.42 345.36 346.78 347.25 346.60 344.91 342.67 341.18 341.56 342.74 343.77 344.26 1985 344.45 345.37 346.72 347.77 348.44 347.97 346.00 343.93 342.66 342.71 343.77 345.17 345.41 1986 345.97 346.40 347.58 349.18 349.80 348.84 346.85 345.07 343.75 343.62 345.24 346.71 346.58 1987 347.28 348.00 349.13 350.61 351.58 351.06 349.40 347.30 346.26 346.54 347.94 349.25 348.70 1988 350.11 351.31 352.33 353.40 354.10 353.57 352.24 350.06 348.61 348.93 349.90 351.18 351.31 1989 352.43 352.88 353.68 355.12 355.83 355.19 353.55 350.93 349.27 349.71 351.34 352.52 352.70 1990 353.67 354.79 355.59 356.49 356.93 356.14 354.15 352.08 350.98 351.21 352.73 354.44 354.10 1991 355.01 355.78 357.22 358.49 359.14 358.16 355.76 353.71 352.21 352.36 353.70 355.29 355.57 1992 356.48 357.03 357.96 359.00 359.69 359.09 356.74 354.85 353.49 353.30 354.35 355.70 356.47 1993 356.56 357.13 357.97 359.28 360.23 359.49 357.57 355.12 353.52 353.92 355.19 356.62 356.88