********************************************************************* *** 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 1972 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 330.43 -99.99 1973 330.80 331.52 332.62 334.04 334.29 332.68 330.66 328.09 326.92 327.86 329.15 330.48 330.76 1974 332.14 333.19 333.82 -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 -99.99 335.33 335.46 334.20 332.20 330.56 329.42 329.79 331.38 333.34 -99.99 1977 335.03 335.87 336.37 336.84 336.79 336.10 334.82 333.22 332.05 333.14 335.03 336.53 335.15 1978 337.86 338.67 339.31 339.87 339.79 338.03 335.27 332.71 332.15 333.78 335.85 337.56 336.74 1979 339.02 340.06 341.12 342.03 341.37 339.54 337.70 335.59 334.56 335.74 337.67 339.24 338.64 1980 341.11 342.26 342.77 343.29 342.65 341.12 339.77 337.79 336.28 337.25 339.48 340.97 340.40 1981 342.24 343.31 344.10 344.89 345.33 344.63 343.13 340.35 337.73 338.32 341.05 342.06 342.26 1982 342.64 343.59 344.23 344.95 344.36 342.90 340.70 337.06 335.88 338.09 340.17 341.73 341.36 1983 343.61 344.68 345.12 345.86 346.71 346.29 343.85 340.88 339.67 340.35 341.53 343.54 343.51 1984 345.83 346.27 346.87 348.03 348.06 347.01 344.85 342.52 341.12 342.16 344.49 346.05 345.27 1985 346.70 347.65 348.99 349.76 349.26 348.29 346.62 343.40 341.93 343.83 346.28 347.89 346.72 1986 348.95 349.55 350.12 350.83 350.67 349.46 348.01 345.24 343.31 344.47 347.05 348.93 348.05 1987 349.63 351.26 352.64 352.63 352.21 351.52 350.25 348.52 347.22 347.87 349.99 351.45 350.43 1988 352.40 352.90 354.03 355.30 354.98 353.90 352.32 350.08 349.25 350.46 352.50 353.73 352.65 1989 353.82 354.14 355.31 356.33 356.79 355.99 354.09 352.49 351.97 352.57 354.35 355.59 354.45 1990 355.90 356.64 357.58 358.86 359.27 357.68 355.13 352.18 351.74 354.96 356.41 355.94 356.02 1991 356.25 357.89 359.58 359.63 359.16 358.30 356.11 353.70 352.22 352.84 355.16 357.98 356.57 1992 359.18 358.85 359.30 361.08 360.78 357.88 355.65 353.78 353.79 355.80 356.71 356.96 357.48 1993 357.97 359.49 362.07 362.72 359.80 358.89 360.78 358.32 353.34 353.82 356.55 358.03 358.48 1994 358.94 360.32 361.95 362.30 361.71 360.72 359.21 356.46 354.07 355.25 358.90 362.69 359.38 1995 365.47 364.74 363.85 364.03 363.40 362.41 360.81 358.35 357.55 360.08 362.65 362.70 362.17 1996 363.63 365.04 365.48 366.00 366.00 364.79 362.04 359.87 359.26 360.26 362.11 362.66 363.10 1997 364.73 366.55 367.29 367.98 367.18 365.85 363.65 360.51 359.57 362.04 364.71 367.13 364.77 1998 368.64 368.67 369.08 369.33 369.04 368.68 367.37 365.33 363.76 366.22 368.34 368.35 367.73 1999 370.23 371.71 371.66 371.57 371.32 370.23 368.45 366.56 365.09 366.28 368.97 369.60 369.31 2000 371.70 374.14 373.15 372.99 373.00 371.72 369.99 367.25 366.16 368.19 371.85 373.53 371.14 2001 373.89 376.13 377.04 375.99 374.70 373.20 371.62 369.27 368.31 369.37 371.11 373.75 372.87 2002 375.17 375.07 376.12 376.72 376.83 375.55 372.58 370.62 369.94 371.89 374.96 376.51 374.33 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.