******************************************************************* *** Atmospheric CO2 mixing ratios (ppmv) derived from in situ *** *** air samples collected at the South Pole, Antarctica *** *** *** *** Source: Kirk W. Thoning *** *** Pieter P. Tans *** *** National Oceanic and Atmospheric Administration *** *** Climate Monitoring and Diagnostics Laboratory *** *** Boulder, Colorado USA 80303 *** *** *** *** February 2000 *** *** *** ******************************************************************* Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1975 329.10 328.80 328.47 328.32 328.60 328.64 329.37 329.80 330.10 330.30 330.20 330.25 329.33 1976 330.05 329.76 329.64 329.64 329.70 329.91 330.29 330.70 331.01 331.12 331.09 331.14 330.34 1977 330.89 330.32 330.27 330.64 331.00 331.39 331.81 332.24 332.70 332.98 332.98 332.74 331.66 1978 332.56 332.38 332.29 332.51 332.95 333.31 333.84 334.44 334.93 335.02 334.87 334.70 333.65 1979 -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 1980 336.13 335.96 336.00 336.22 336.60 336.93 337.38 337.65 337.90 338.09 338.04 338.03 337.08 1981 337.84 337.77 337.88 337.91 338.07 338.29 338.72 338.95 339.17 339.13 338.93 338.50 338.43 1982 338.45 338.60 338.37 338.56 338.88 338.93 339.24 339.61 339.86 339.77 339.52 339.24 339.09 1983 339.67 339.61 339.71 340.05 -99.99 340.88 341.15 341.85 342.08 342.16 342.23 342.04 -99.99 1984 341.90 341.86 341.65 341.73 341.88 342.08 342.52 343.05 343.35 343.44 343.24 343.02 342.48 1985 343.13 342.94 342.81 342.96 343.27 343.58 344.06 344.53 344.76 344.78 344.84 344.58 343.85 1986 344.53 344.41 344.39 344.47 344.60 344.89 345.37 345.77 346.03 346.23 345.98 345.76 345.20 1987 345.72 345.55 345.54 345.72 345.95 346.41 346.92 347.47 347.94 348.02 348.17 348.10 346.79 1988 348.06 347.92 347.98 348.18 348.28 348.50 348.89 349.33 349.63 349.70 349.70 349.69 348.82 1989 349.62 349.68 349.60 349.68 349.92 350.22 350.58 351.00 351.08 351.24 351.29 350.87 350.40 1990 350.76 350.57 350.64 350.91 351.25 351.58 352.06 352.40 352.70 352.74 352.74 352.30 351.72 1991 352.21 351.92 351.73 351.97 352.22 352.54 352.95 353.34 353.48 353.51 353.73 353.60 352.77 1992 353.32 353.07 353.01 353.56 353.93 354.34 354.80 355.19 355.20 355.13 354.96 354.73 354.27 1993 354.55 354.46 354.33 354.43 354.58 354.85 355.32 355.77 355.99 355.99 355.85 355.62 355.15 1994 355.48 355.45 355.51 355.63 355.76 356.04 356.46 357.14 357.52 357.56 357.52 357.40 356.46 1995 357.22 357.23 357.40 357.40 357.63 357.87 358.35 358.78 359.10 359.29 359.39 359.40 358.26 1996 359.28 359.24 359.18 359.22 359.38 359.60 360.02 360.43 360.55 360.60 360.56 360.52 359.88 1997 360.39 360.23 360.22 360.47 360.63 360.98 361.30 361.63 361.95 362.02 362.12 362.15 361.17 1998 361.98 362.10 362.26 362.58 362.90 363.39 363.92 364.56 364.86 364.91 364.93 364.88 363.61 Atmospheric CO2 mixing ratios are expressed in parts per million by volume (ppmv) and reported relative to the dry air WMO mole fraction scale. Monthly means are derived from hourly and daily means that represent baseline (background) conditions. Annual means are the arithmetic means of the monthly values calculated by CDIAC. Annual means are provided only for years with complete monthly records. Missing values are denoted by -99.99.