********************************************************************* *** 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 1968 323.63 325.10 326.06 326.52 326.45 323.98 320.08 318.19 318.90 321.11 323.21 324.05 323.11 1969 324.55 325.61 327.11 327.93 327.15 325.04 321.14 318.48 319.46 322.16 323.88 325.43 324.00 1970 326.65 327.40 329.03 330.47 329.14 326.12 322.28 319.47 320.57 324.18 326.09 326.40 325.65 1971 327.48 328.89 329.72 330.18 329.09 324.62 320.75 319.70 320.19 323.05 325.63 326.29 325.47 1972 327.44 328.74 329.27 330.36 329.31 324.32 320.60 320.38 322.15 325.37 328.51 329.86 326.36 1973 330.75 331.70 332.44 333.23 333.52 331.19 327.38 325.48 326.58 328.24 330.48 331.87 330.24 1974 332.59 333.76 335.16 336.09 335.02 332.25 -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 332.79 334.25 334.63 335.03 334.49 332.32 330.22 328.10 327.64 329.96 332.09 333.55 332.09 1977 334.80 335.75 336.51 337.26 337.28 335.28 332.75 331.51 331.21 332.73 334.95 336.50 334.71 1978 337.35 338.03 338.44 338.52 338.70 337.41 333.92 330.99 330.85 333.43 334.98 336.62 335.77 1979 338.11 338.74 339.89 340.54 340.50 338.13 334.41 332.63 332.61 334.03 335.82 336.79 336.85 1980 338.31 339.91 340.75 341.03 338.74 335.10 333.38 333.30 334.17 335.58 337.85 339.62 337.31 1981 341.26 343.03 343.48 343.17 341.92 339.54 337.18 335.36 335.39 338.05 340.97 341.79 340.10 1982 342.30 343.70 344.79 345.16 343.76 340.23 336.42 334.68 336.39 339.52 340.69 341.36 340.75 1983 343.35 344.71 345.23 346.06 345.08 342.41 339.44 336.45 336.72 340.35 343.63 345.75 342.43 1984 345.73 346.22 347.98 349.05 348.38 345.11 340.08 338.58 340.73 343.24 344.87 345.90 344.66 1985 347.08 347.77 348.10 348.56 347.80 345.72 344.69 343.77 342.07 343.52 346.62 347.55 346.10 1986 347.89 349.09 349.62 349.80 348.66 345.64 344.23 344.15 344.29 345.09 346.21 347.70 346.86 1987 349.02 350.37 351.83 351.79 350.78 349.59 347.42 344.85 345.18 347.12 349.41 351.26 349.05 1988 352.56 353.68 354.42 355.38 354.41 351.36 349.69 348.31 347.96 349.56 352.45 354.10 351.99 1989 354.33 355.01 355.54 355.88 355.70 354.74 352.68 349.73 349.23 351.21 353.68 354.63 353.53 1990 355.45 357.10 357.59 357.91 358.05 356.00 352.12 350.33 351.35 352.36 353.75 355.81 354.82 1991 357.30 358.42 359.43 360.05 358.69 356.78 353.84 351.42 351.50 353.48 356.19 357.81 356.24 1992 358.95 359.45 360.18 359.85 357.65 356.74 356.26 354.15 352.92 354.25 355.99 357.25 356.97 1993 358.63 359.43 360.60 361.46 360.62 358.72 354.58 351.74 353.42 356.13 357.13 357.95 357.53 1994 359.56 360.91 361.90 362.76 361.95 359.13 357.91 356.99 355.87 357.11 358.91 360.43 359.45 1995 361.81 362.07 362.70 364.40 365.11 362.59 358.78 356.83 357.54 359.28 361.20 362.35 361.22 1996 363.60 364.72 365.27 365.93 366.56 363.92 360.96 360.16 359.08 360.34 362.69 363.84 363.09 1997 365.27 366.43 366.95 367.30 365.86 362.87 360.46 360.22 359.98 361.03 364.44 366.34 363.93 1998 366.80 367.67 368.99 369.78 368.43 366.69 364.94 362.03 361.79 365.81 367.83 368.12 366.57 1999 369.60 370.80 371.20 371.87 372.15 369.26 364.53 362.66 363.98 366.21 368.17 369.84 368.36 2000 370.36 371.70 373.14 372.99 371.89 370.22 369.29 367.63 366.74 368.30 370.09 371.47 370.32 2001 372.87 373.40 374.32 374.97 373.26 372.83 373.42 370.71 368.54 369.31 371.10 373.57 372.36 2002 375.02 376.15 376.61 376.57 375.73 373.94 372.45 370.99 370.51 372.04 374.78 376.06 374.24 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.