******************************************************************** *** Atmospheric CO2-curve values (ppmv) derived from flask air *** *** samples collected at Christmas Island, Pacific *** *** *** *** Source: R. F. Keeling, S. C. Piper, A. F. Bollenbacher *** *** and S. J. Walker *** *** Carbon Dioxide Research Group *** *** Scripps Institution of Oceanography (SIO) *** *** University of California *** *** La Jolla, California USA 92093-0444 *** *** *** *** May 2008 *** ******************************************************************** Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann. Ave. 1975 331.42 331.72 332.54 333.27 332.87 332.51 332.36 331.71 331.28 331.24 331.39 332.13 332.04 1976 332.77 333.01 333.78 334.39 333.88 333.41 333.14 332.38 331.88 331.80 331.97 332.77 332.93 1977 333.50 333.87 334.74 335.50 335.11 334.72 334.53 333.82 333.35 333.29 333.44 334.22 334.17 1978 334.92 335.23 336.05 336.78 336.39 336.03 335.88 335.23 334.82 334.81 335.02 335.86 335.59 1979 336.61 336.97 337.83 338.58 338.19 337.81 337.63 336.95 336.51 336.49 336.70 337.55 337.32 1980 338.33 338.71 339.64 340.40 340.02 339.68 339.53 338.86 338.43 338.40 338.57 339.35 339.16 1981 340.04 340.33 341.11 341.78 341.30 340.84 340.59 339.85 339.36 339.30 339.47 340.26 340.35 1982 340.98 341.30 342.13 342.84 342.41 341.98 341.77 341.06 340.59 340.54 340.73 341.55 341.49 1983 342.30 342.67 343.53 344.29 343.89 343.49 343.29 342.59 342.14 342.11 342.32 343.18 342.98 1984 343.97 344.37 345.30 346.06 345.66 345.27 345.05 344.32 343.83 343.76 343.93 344.72 344.69 1985 345.45 345.79 346.63 347.35 346.93 346.50 346.27 345.53 345.02 344.94 345.09 345.87 345.95 1986 346.58 346.92 347.76 348.50 348.11 347.71 347.52 346.81 346.33 346.26 346.41 347.20 347.18 1987 347.94 348.31 349.22 350.05 349.76 349.49 349.42 348.85 348.51 348.57 348.86 349.76 349.06 1988 350.59 351.00 351.94 352.69 352.30 351.93 351.76 351.09 350.68 350.67 350.89 351.72 351.44 1989 352.45 352.78 353.61 354.32 353.88 353.46 353.24 352.53 352.05 351.98 352.14 352.92 352.95 1990 353.63 353.94 354.74 355.44 355.01 354.59 354.39 353.70 353.24 353.19 353.36 354.14 354.11 1991 354.83 355.13 355.93 356.63 356.19 355.77 355.55 354.83 354.35 354.29 354.45 355.24 355.27 1992 355.94 356.26 357.10 357.77 357.30 356.86 356.60 355.83 355.32 355.22 355.35 356.11 356.31 1993 356.81 357.13 357.96 358.72 358.33 357.96 357.79 357.11 356.66 356.61 356.79 357.60 357.46 1994 358.33 358.69 359.56 360.33 359.97 359.63 359.49 358.86 358.46 358.46 358.68 359.52 359.17 1995 360.28 360.65 361.51 362.28 361.90 361.55 361.41 360.79 360.43 360.48 360.77 361.67 361.14 1996 362.49 362.90 363.81 364.54 364.11 363.70 363.46 362.70 362.19 362.09 362.20 362.94 363.09 1997 363.60 363.88 364.67 365.35 364.91 364.49 364.29 363.62 363.21 363.24 363.53 364.46 364.10 1998 365.33 365.82 366.80 367.68 367.40 367.13 367.05 366.47 366.11 366.15 366.40 367.25 366.63 1999 368.00 368.34 369.17 369.87 369.42 369.00 368.79 368.10 367.66 367.64 367.86 368.70 368.55 2000 369.46 369.81 370.69 371.40 370.97 370.57 370.36 369.66 369.22 369.19 369.39 370.21 370.08 2001 370.95 371.29 372.13 372.87 372.46 372.07 371.90 371.23 370.81 370.82 371.06 371.93 371.63 2002 372.74 373.16 374.07 374.89 374.56 374.25 374.14 373.53 373.15 373.18 373.43 374.30 373.78 2003 375.09 375.48 376.37 377.15 376.79 376.44 376.30 375.65 375.24 375.25 375.47 376.32 375.96 2004 377.09 377.46 378.36 379.09 378.67 378.29 378.10 377.43 377.02 377.02 377.26 378.12 377.83 2005 378.91 379.32 380.22 381.02 380.68 380.35 380.22 379.59 379.19 379.21 379.45 380.31 379.87 2006 381.08 381.45 382.29 383.02 382.59 382.17 381.96 381.26 380.81 380.78 380.99 381.82 381.69 2007 382.60 382.99 383.89 384.69 384.35 384.03 383.92 383.31 382.95 383.01 383.30 384.22 383.61 Values above are taken from a curve consisting of 4 harmonics plus a stiff spline and a linear gain factor, fit to monthly concentration values adjusted to represent 2400 hours on the 15th day of each month. Data used to derive this curve are shown in the accompanying graph. Units are parts per million by volume (ppmv) expressed in the 2003A SIO manometric mole fraction scale. The "annual average" is the arithmetic mean of the twelve monthly values.