******************************************************************* *** Atmospheric CO2 concentrations (ppmv) derived from in situ *** *** air samples collected at Mauna Loa Observatory, Hawaii *** *** *** *** Source: C.D. Keeling *** *** T.P. Whorf, and the Carbon Dioxide Research Group *** *** Scripps Institution of Oceanography (SIO) *** *** University of California *** *** La Jolla, California USA 92093-0444 *** *** *** *** June 2004 *** *** *** *** Monthly values are expressed in parts per million (ppm) and *** *** reported in the 2003A SIO manometric mole fraction scale. *** *** The monthly values have been adjusted to the 15th of each *** *** month. Missing values are denoted by -99.99. The "annual" *** *** average is the arithmetic mean of the twelve monthly *** *** values. In years with one or two missing monthly values, *** *** annual values were calculated by substituting a fit value *** *** (4-harmonics with gain factor and spline) for that month *** *** and then averaging the twelve monthly values. *** ******************************************************************* Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual Annual-Fit 1958 -99.99 -99.99 315.71 317.45 317.50 -99.99 315.86 314.93 313.19 -99.99 313.34 314.67 -99.99 -99.99 1959 315.58 316.47 316.65 317.71 318.29 318.16 316.55 314.80 313.84 313.34 314.81 315.59 315.98 316.00 1960 316.43 316.97 317.58 319.03 320.03 319.59 318.18 315.91 314.16 313.83 315.00 316.19 316.91 316.91 1961 316.89 317.70 318.54 319.48 320.58 319.78 318.58 316.79 314.99 315.31 316.10 317.01 317.65 317.63 1962 317.94 318.56 319.69 320.58 321.01 320.61 319.61 317.40 316.26 315.42 316.69 317.69 318.45 318.46 1963 318.74 319.08 319.86 321.39 322.24 321.47 319.74 317.77 316.21 315.99 317.07 318.36 318.99 319.02 1964 319.57 -99.99 -99.99 -99.99 322.23 321.89 320.44 318.70 316.70 316.87 317.68 318.71 -99.99 319.52 1965 319.44 320.44 320.89 322.13 322.16 321.87 321.21 318.87 317.81 317.30 318.87 319.42 320.03 320.09 1966 320.62 321.59 322.39 323.70 324.07 323.75 322.40 320.37 318.64 318.10 319.79 321.03 321.37 321.34 1967 322.33 322.50 323.04 324.42 325.00 324.09 322.55 320.92 319.26 319.39 320.72 321.96 322.18 322.13 1968 322.57 323.15 323.89 325.02 325.57 325.36 324.14 322.11 320.33 320.25 321.32 322.90 323.05 323.11 1969 324.00 324.42 325.64 326.66 327.38 326.70 325.89 323.67 322.38 321.78 322.85 324.12 324.62 324.60 1970 325.06 325.98 326.93 328.13 328.07 327.66 326.35 324.69 323.10 323.07 324.01 325.13 325.68 325.65 1971 326.17 326.68 327.18 327.78 328.92 328.57 327.37 325.43 323.36 323.56 324.80 326.01 326.32 326.32 1972 326.77 327.63 327.75 329.72 330.07 329.09 328.05 326.32 324.84 325.20 326.50 327.55 327.46 327.52 1973 328.54 329.56 330.30 331.50 332.48 332.07 330.87 329.31 327.51 327.18 328.16 328.64 329.68 329.61 1974 329.35 330.71 331.48 332.65 333.09 332.25 331.18 329.40 327.44 327.37 328.46 329.58 330.25 330.29 1975 330.40 331.41 332.04 333.31 333.96 333.59 331.91 330.06 328.56 328.34 329.49 330.76 331.15 331.16 1976 331.74 332.56 333.50 334.58 334.87 334.34 333.05 330.94 329.30 328.94 330.31 331.68 332.15 332.18 1977 332.92 333.42 334.70 336.07 336.74 336.27 334.93 332.75 331.58 331.16 332.40 333.85 333.90 333.88 1978 334.97 335.39 336.64 337.76 338.01 337.89 336.54 334.68 332.76 332.54 333.92 334.95 335.50 335.52 1979 336.23 336.76 337.96 338.89 339.47 339.29 337.73 336.09 333.91 333.86 335.29 336.73 336.85 336.89 1980 338.01 338.36 340.08 340.77 341.46 341.17 339.56 337.60 335.88 336.01 337.10 338.21 338.69 338.67 1981 339.23 340.47 341.38 342.51 342.91 342.25 340.49 338.43 336.69 336.85 338.36 339.61 339.93 339.95 1982 340.75 341.61 342.70 343.56 344.13 343.35 342.06 339.82 337.97 337.86 339.26 340.49 341.13 341.09 1983 341.37 342.52 343.10 344.94 345.75 345.32 343.99 342.39 339.86 339.99 341.16 342.99 342.78 342.75 1984 343.70 344.51 345.28 347.08 347.43 346.79 345.40 343.28 341.07 341.35 342.98 344.22 344.42 344.44 1985 344.97 346.00 347.43 348.35 348.93 348.25 346.56 344.69 343.09 342.80 344.24 345.56 345.90 345.86 1986 346.29 346.96 347.86 349.55 350.21 349.54 347.94 345.91 344.86 344.17 345.66 346.90 347.15 347.14 1987 348.02 348.47 349.42 350.99 351.84 351.25 349.52 348.10 346.44 346.36 347.81 348.96 348.93 348.99 1988 350.43 351.72 352.22 353.59 354.22 353.79 352.39 350.44 348.72 348.88 350.07 351.34 351.48 351.44 1989 352.76 353.07 353.68 355.42 355.67 355.13 353.90 351.67 349.80 349.99 351.30 352.53 352.91 352.94 1990 353.66 354.70 355.39 356.20 357.16 356.22 354.82 352.91 350.96 351.18 352.83 354.21 354.19 354.19 1991 354.72 355.75 357.16 358.60 359.34 358.24 356.17 354.03 352.16 352.21 353.75 354.99 355.59 355.62 1992 355.98 356.72 357.81 359.15 359.66 359.25 357.03 355.00 353.01 353.31 354.16 355.40 356.37 356.36 1993 356.70 357.16 358.38 359.46 360.28 359.60 357.57 355.52 353.70 353.98 355.33 356.80 357.04 357.10 1994 358.36 358.91 359.97 361.26 361.68 360.95 359.55 357.49 355.84 355.99 357.58 359.04 358.88 358.86 1995 359.96 361.00 361.64 363.45 363.79 363.26 361.90 359.46 358.06 357.75 359.56 360.70 360.88 360.90 1996 362.05 363.25 364.03 364.72 365.41 364.97 363.65 361.49 359.46 359.60 360.76 362.33 362.64 362.58 1997 363.18 364.00 364.57 366.35 366.79 365.62 364.47 362.51 360.19 360.77 362.43 364.28 363.76 363.84 1998 365.32 366.15 367.31 368.61 369.29 368.87 367.64 365.77 363.90 364.23 365.46 366.97 366.63 366.58 1999 368.15 368.87 369.59 371.14 371.00 370.35 369.27 366.94 364.63 365.12 366.67 368.01 368.31 368.30 2000 369.14 369.46 370.52 371.66 371.82 371.70 370.12 368.12 366.62 366.73 368.29 369.53 369.48 369.47 2001 370.28 371.50 372.12 372.87 374.02 373.30 371.62 369.55 367.96 368.09 369.68 371.24 371.02 371.03 2002 372.43 373.09 373.52 374.86 375.55 375.41 374.02 371.49 370.71 370.25 372.08 373.78 373.10 373.07 2003 374.68 375.63 376.11 377.65 378.35 378.13 376.62 374.50 372.99 373.00 374.35 375.70 375.64 375.61