********************************************************************* *** Atmospheric Carbon Dioxide Mixing Ratios from the *** *** NOAA CMDL Carbon Cycle Cooperative Global Air Sampling *** *** Network, 1968-2002 *** *** *** *** March 2005 *** *** *** *** Source: Thomas J. Conway *** *** Pieter P. Tans *** *** NOAA Climate Monitoring and Diagnostics Laboratory *** *** 325 Broadway *** *** Boulder, Colorado, U.S.A. *** ********************************************************************* Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann 1973 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 330.27 330.24 330.08 330.09 330.29 -99.99 1974 330.61 331.16 331.32 331.07 331.37 331.14 330.52 330.62 330.77 331.05 330.45 329.98 330.84 1975 330.64 330.62 330.19 329.63 329.66 330.61 330.86 330.74 331.50 331.60 330.91 330.54 330.63 1976 330.47 330.55 330.82 331.18 331.43 331.15 330.99 331.54 331.90 332.19 332.63 332.96 331.48 1977 333.00 332.59 332.22 332.68 332.81 332.56 332.82 332.90 332.62 332.55 332.97 333.71 332.79 1978 334.03 333.79 334.40 334.50 334.30 334.89 334.56 334.22 334.39 334.50 334.39 334.14 334.34 1979 334.74 335.46 335.75 335.91 335.63 335.76 335.76 335.78 336.17 336.69 336.79 336.68 335.93 1980 337.35 338.00 337.69 337.65 338.33 338.57 338.44 338.50 338.39 338.26 338.55 338.96 338.22 1981 339.16 338.99 339.46 339.41 338.60 338.83 339.14 339.13 338.96 339.11 339.53 339.85 339.18 1982 340.47 340.79 340.43 339.91 339.45 339.56 340.26 340.63 340.25 340.00 340.29 340.75 340.23 1983 340.75 340.49 340.56 340.79 341.16 341.64 341.82 341.66 341.61 341.84 341.98 342.39 341.39 1984 342.97 343.08 342.88 342.36 341.98 342.35 342.76 343.05 343.15 343.06 343.37 344.02 342.92 1985 344.26 344.63 344.77 344.26 343.88 344.21 344.53 344.45 344.29 344.47 344.91 345.13 344.48 1986 345.44 345.66 345.51 345.17 345.38 346.20 345.87 345.31 345.62 345.89 346.02 346.09 345.68 1987 346.44 347.03 347.02 346.60 346.69 346.99 347.22 347.63 347.99 348.20 348.63 349.06 347.46 1988 349.35 349.75 350.22 350.52 350.27 349.91 350.01 350.07 349.88 350.27 350.88 351.42 350.21 1989 351.83 351.91 351.82 352.12 352.01 351.33 351.38 351.51 351.40 351.62 351.86 352.09 351.74 1990 352.30 352.38 352.98 352.95 352.40 352.61 352.87 353.00 352.98 352.94 353.19 353.67 352.86 1991 354.29 354.81 354.47 354.02 354.12 354.20 354.39 354.16 353.79 353.90 354.52 354.89 354.30 1992 354.51 354.79 354.89 354.59 354.70 355.01 355.48 355.44 355.15 355.12 355.15 355.40 355.02 1993 355.42 355.73 356.04 355.43 354.95 355.36 355.70 355.94 355.85 355.84 356.34 356.70 355.78 1994 356.90 357.50 357.71 357.06 356.96 357.20 357.12 357.06 357.17 357.48 357.95 358.33 357.37 1995 358.60 359.06 359.06 358.76 358.97 359.18 359.37 359.35 359.30 359.49 359.93 360.58 359.30 1996 361.16 361.68 361.20 360.30 360.59 360.88 360.67 360.82 360.96 360.91 361.27 361.78 361.02 1997 361.96 362.17 362.31 362.10 361.49 361.13 361.62 361.89 362.17 362.68 363.11 363.34 362.16 1998 363.32 363.33 363.37 363.37 364.01 364.63 364.71 365.02 365.39 365.56 365.99 366.45 364.60 1999 366.73 366.62 366.39 366.89 367.43 367.12 367.08 367.23 366.94 366.87 367.23 367.64 367.01 2000 368.11 368.43 368.36 367.74 367.05 367.28 368.11 368.37 368.19 368.37 368.92 369.25 368.18 2001 369.46 369.89 369.78 368.84 368.59 369.59 370.53 370.19 369.72 370.05 370.54 370.88 369.84 2002 371.16 371.58 371.81 371.24 370.92 371.30 371.79 371.97 371.99 372.40 372.94 373.27 371.86 Monthly measurements are reported in parts per million (ppm) and are directly traceable to the WMO CO2 mole fraction scale. Annual values are the arithmetic means of the 12 monthly values.