% Etheridge, D.M., L.P. Steele, R.L. Langenfelds, R.J. Francey, J.-M. Barnola, and V.I. Morgan. 1996. % Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn. Journal of Geophysical Research 101:4115-4128. % % Mean Air Age, CO2, 20 Year Smoothed, % year A.D. ppm 1832 284.3 1833 284.1 1834 284.0 1835 283.8 1836 283.7 1837 283.5 1838 283.4 1839 283.4 1840 283.4 1841 283.4 1842 283.5 1843 283.6 1844 283.7 1845 283.9 1846 284.1 1847 284.2 1848 284.4 1849 284.6 1850 284.7 1851 284.9 1852 285.0 1853 285.1 1854 285.3 1855 285.4 1856 285.6 1857 285.7 1858 285.9 1859 286.1 1860 286.2 1861 286.4 1862 286.5 1863 286.6 1864 286.8 1865 286.9 1866 287.0 1867 287.1 1868 287.2 1869 287.4 1870 287.5 1871 287.7 1872 287.9 1873 288.1 1874 288.4 1875 288.7 1876 289.0 1877 289.4 1878 289.8 1879 290.2 1880 290.7 1881 291.2 1882 291.7 1883 292.1 1884 292.6 1885 293.0 1886 293.3 1887 293.6 1888 293.8 1889 294.0 1890 294.2 1891 294.3 1892 294.5 1893 294.6 1894 294.7 1895 294.8 1896 294.9 1897 295.0 1898 295.2 1899 295.5 1900 295.8 1901 296.1 1902 296.5 1903 296.8 1904 297.2 1905 297.6 1906 298.1 1907 298.5 1908 298.9 1909 299.3 1910 299.7 1911 300.1 1912 300.4 1913 300.8 1914 301.1 1915 301.4 1916 301.7 1917 302.1 1918 302.4 1919 302.7 1920 303.0 1921 303.4 1922 303.8 1923 304.1 1924 304.5 1925 305.0 1926 305.4 1927 305.8 1928 306.3 1929 306.8 1930 307.2 1931 307.7 1932 308.2 1933 308.6 1934 309.0 1935 309.4 1936 309.8 1937 310.0 1938 310.2 1939 310.3 1940 310.4 1941 310.4 1942 310.3 1943 310.2 1944 310.1 1945 310.1 1946 310.1 1947 310.2 1948 310.3 1949 310.5 1950 310.7 1951 311.1 1952 311.5 1953 311.9 1954 312.4 1955 313.0 1956 313.6 1957 314.2 1958 314.9 1959 315.6 1960 316.3 1961 317.0 1962 317.7 1963 318.4 1964 319.2 1965 320.0 1966 320.8 1967 321.8 1968 322.8 1969 323.8 1970 324.8 1971 325.8 1972 326.9 1973 328.0 1974 329.2 1975 330.3 1976 331.5 1977 332.6 1978 333.7