******************************************************************* *** Atmospheric CO2 mixing ratios (ppmv) derived from in situ *** *** air samples collected at Point Barrow, Alaska *** *** *** *** Source: Kirk W. Thoning *** *** Pieter P. Tans *** *** National Oceanic and Atmospheric Administration *** *** Climate Monitoring and Diagnostics Laboratory *** *** Boulder, Colorado USA 80303 *** *** *** *** February 2000 *** *** *** ******************************************************************* Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1973 -99.99 -99.99 -99.99 -99.99 -99.99 -99.99 324.26 322.74 324.56 329.58 333.77 334.56 -99.99 1974 339.00 337.87 337.51 337.95 337.71 336.76 330.89 324.69 326.09 329.91 332.85 336.08 333.94 1975 337.60 337.94 337.99 338.55 338.97 336.14 329.35 323.67 324.39 328.71 334.02 335.85 333.60 1976 336.57 336.20 337.32 337.55 337.32 336.23 330.16 323.60 325.05 329.87 334.02 336.73 333.39 1977 336.86 336.95 338.32 339.15 339.39 337.81 330.10 325.66 326.90 332.15 334.78 338.71 334.73 1978 339.15 340.18 341.48 340.95 340.77 339.44 332.57 327.76 328.48 332.81 338.71 339.43 336.81 1979 340.21 341.29 342.49 342.35 342.84 341.96 333.00 327.82 330.05 333.41 338.00 341.46 337.91 1980 341.83 342.40 343.57 344.01 343.59 342.68 338.41 332.05 332.08 340.61 344.32 343.71 340.77 1981 344.26 345.55 344.61 345.79 346.88 344.16 336.81 331.71 333.55 338.92 342.34 344.86 341.62 1982 345.69 347.54 348.06 348.39 348.01 345.77 339.08 332.97 333.48 338.29 342.11 344.67 342.84 1983 347.14 346.95 348.00 348.16 348.30 346.90 340.38 333.75 335.35 340.47 346.54 346.65 344.05 1984 350.93 350.89 350.01 349.78 350.65 348.35 341.57 335.79 338.71 342.01 345.02 348.50 346.02 1985 349.69 349.51 350.53 351.52 352.50 350.07 343.50 337.71 338.62 343.25 346.92 349.66 346.96 1986 350.21 351.63 353.42 353.09 353.33 351.43 344.51 339.45 342.03 345.03 348.71 351.09 348.66 1987 352.36 352.72 353.90 353.85 354.44 352.19 346.45 340.40 340.37 348.71 349.62 352.71 349.81 1988 354.87 356.23 356.56 357.40 356.83 355.27 348.43 343.10 345.87 350.59 354.28 357.86 353.11 1989 360.88 358.16 359.15 359.27 358.74 357.04 349.34 344.48 346.18 351.19 355.81 358.29 354.88 1990 359.81 359.85 361.24 361.04 360.48 356.77 349.49 345.74 346.37 353.87 356.63 359.21 355.88 1991 360.82 362.09 361.16 361.73 361.52 359.80 353.69 347.44 348.28 356.21 358.34 360.87 357.66 1992 361.62 362.21 362.48 362.55 362.77 360.42 353.58 347.09 347.69 353.66 357.24 361.05 357.70 1993 362.45 361.81 363.43 363.03 363.22 360.51 351.55 347.69 349.14 354.12 358.41 360.17 357.96 1994 361.83 363.76 365.04 364.26 364.07 362.76 354.37 349.03 350.41 357.37 360.80 364.28 359.83 1995 364.49 366.13 366.27 366.60 365.78 364.01 356.53 351.49 355.24 357.90 363.80 366.94 362.10 1996 366.49 367.45 367.61 367.99 368.89 367.14 360.08 355.48 353.91 361.75 364.11 366.58 363.96 1997 369.30 369.03 368.60 369.33 369.22 366.93 359.17 353.27 356.70 361.79 366.55 367.84 364.81 1998 369.32 370.29 370.59 371.27 371.33 369.18 361.53 357.04 361.14 365.65 368.96 372.56 367.41 Atmospheric CO2 mixing ratios are expressed in parts per million by volume (ppmv) and reported relative to the dry air WMO mole fraction scale. Monthly means are derived from hourly and daily means that represent baseline (background) conditions. Annual means are the arithmetic means of the monthly values calculated by CDIAC. Annual means are provided only for years with complete monthly records. Missing values denoted by -99.99.