********************************************************************* *** 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 1971 -99.99 -99.99 -99.99 -99.99 332.19 330.24 323.65 317.71 318.78 322.85 327.31 331.06 -99.99 1972 333.39 334.26 334.15 334.47 335.49 333.32 325.65 319.11 322.06 327.25 330.67 333.46 330.27 1973 334.71 335.43 336.49 336.94 336.56 334.04 327.51 322.23 323.66 328.58 332.08 334.71 331.91 1974 337.03 337.86 337.83 337.55 338.77 338.21 330.51 323.08 323.74 328.93 333.26 335.69 333.54 1975 336.61 336.47 336.39 336.57 336.26 334.60 329.69 324.46 324.97 329.54 333.50 336.28 332.95 1976 337.48 337.90 338.47 338.73 338.08 335.67 329.97 324.76 325.10 329.60 333.11 336.03 333.74 1977 337.67 337.73 338.32 339.38 339.71 337.63 331.48 326.36 326.57 329.88 334.38 337.54 334.72 1978 339.81 341.06 341.01 341.07 340.93 339.01 333.39 327.40 327.70 332.40 337.07 338.97 336.65 1979 340.07 341.30 342.07 342.31 343.21 341.34 333.81 327.39 328.91 334.35 337.66 338.64 337.59 1980 340.92 342.72 343.28 344.27 345.14 342.91 337.26 332.21 332.54 336.95 340.60 342.98 340.15 1981 344.74 345.39 345.45 345.97 346.47 343.87 336.38 330.76 332.57 338.26 342.12 344.48 341.37 1982 346.06 347.07 347.54 347.30 347.40 345.46 339.34 333.10 332.97 338.27 342.34 344.87 342.64 1983 346.57 347.14 347.60 347.87 348.26 346.53 339.84 333.79 333.95 340.41 345.24 347.02 343.69 1984 349.01 350.37 349.94 349.64 350.32 348.37 341.31 335.91 337.52 341.44 344.85 348.12 345.57 1985 349.43 349.36 350.34 351.76 352.15 349.53 343.46 337.38 338.44 343.50 347.31 348.87 346.79 1986 350.72 352.92 353.40 353.10 353.07 350.34 343.97 338.80 341.90 347.48 350.36 352.04 349.01 1987 353.10 353.70 354.09 354.33 354.98 352.92 345.80 339.97 340.89 345.66 349.80 352.65 349.82 1988 355.63 357.05 357.28 357.83 357.65 354.98 348.05 343.13 345.04 350.46 355.01 358.16 353.36 1989 359.02 358.66 359.68 360.03 359.45 358.45 350.88 342.81 345.22 351.68 356.00 359.36 355.10 1990 360.65 361.12 361.71 361.65 361.47 356.82 348.54 344.63 346.97 352.80 356.59 359.83 356.07 1991 361.78 361.74 362.15 362.17 361.91 360.11 353.61 346.92 348.49 354.68 358.58 360.55 357.72 1992 361.86 362.06 362.39 362.79 362.56 360.25 354.01 347.36 348.32 352.77 356.85 360.77 357.67 1993 362.52 362.75 363.38 363.70 363.48 359.67 352.36 347.96 349.88 354.61 359.00 361.23 358.38 1994 362.60 364.23 364.86 364.17 364.41 362.13 353.39 347.75 350.43 356.37 361.49 364.15 359.67 1995 365.62 366.66 366.58 366.35 366.16 363.70 356.51 351.44 352.96 357.88 363.43 366.00 361.94 1996 366.86 368.09 367.95 368.04 369.40 368.16 361.89 354.69 355.50 361.11 363.69 366.19 364.30 1997 368.90 369.18 368.78 369.63 370.53 367.74 358.94 354.54 357.66 362.15 365.66 367.90 365.13 1998 369.14 370.32 370.99 370.95 371.60 369.73 362.28 357.27 360.11 364.93 369.18 373.01 367.46 1999 374.14 373.79 374.14 374.65 375.40 372.17 364.35 359.05 360.45 365.50 371.47 373.83 369.91 2000 374.88 375.66 375.07 375.36 376.39 373.49 366.33 360.35 361.90 367.01 370.97 373.50 370.91 2001 375.32 376.27 376.84 377.31 377.56 374.80 366.46 361.03 363.31 368.86 373.35 376.39 372.29 2002 377.96 378.18 378.96 378.94 378.46 376.74 369.68 363.28 365.29 371.27 375.52 377.92 374.35 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.