| Year | CO2 (ppm) |
| 1969 | 323.2 |
| 1968 | 323.7 |
| 1965 | 319.5 |
| 1965 | 318.8 |
| 1963 | 318.2 |
| 1962 | 318.7 |
| 1962 | 317 |
| 1962 | 319.4 |
| 1962 | 317 |
| 1953 | 311.9 |
| 1953 | 311 |
| 1953 | 312.7 |
| 1944 | 309.7 |
| 1939 | 311 |
| 1938 | 310.5 |
| 1932 | 307.8 |
| 1924 | 304.8 |
| 1924 | 304.1 |
| 1915 | 301.3 |
| 1912 | 300.7 |
| 1905 | 296.9 |
| 1905 | 298.5 |
| 1898 | 294.7 |
| 1892 | 294.6 |
| 1886 | 293.7 |
| 1882 | 291.9 |
| 1877 | 288.8 |
| 1869 | 287.4 |
| 1861 | 286.6 |
| 1854 | 284.9 |
| 1850 | 285.2 |
| 1840 | 283 |
| 1978 | 335.2 |
| 1978 | 332 |
| 1975 | 331.2 |
| 1973 | 328.1 |
| 1971 | 324.1 |
| 1970 | 325.2 |
| 1970 | 324.7 |
| 1948 | 309.9 |
| 1940 | 310.5 |
| 1934 | 309.2 |
| 1832 | 284.5 |
| 1959 | 315.7 |
| 1954 | 313.6 |
| 1954 | 314.7 |
| 1954 | 314.1 |
| 1948 | 311.4 |
| 1939 | 309.2 |
| 1936 | 307.9 |
| 1929 | 305.2 |
| 1926 | 305 |
| 1905 | 299 |
| 1899 | 296.5 |
| 1891 | 294.7 |
| 1845 | 286.1 |
| 1825 | 285.1 |
| 1796 | 283.7 |
| 1794 | 281.6 |
| 1777 | 279.5 |
| 1760 | 276.7 |
| 1749 | 277.2 |
| 1747 | 276.9 |
| 1720 | 277.5 |
| 1692 | 276.5 |
| 1679 | 275.9 |
| 1647 | 277.2 |
| 1604 | 274.3 |
| 1589 | 278.7 |
| 1570 | 281.9 |
| 1547 | 282.8 |
| 1527 | 283.2 |
| 1499 | 282.4 |
| 1465 | 279.6 |
| 1446 | 281.7 |
| 1387 | 280 |
| 1387 | 280.4 |
| 1327 | 283.4 |
| 1246 | 281.7 |
| 1196 | 283.9 |
| 1146 | 283.8 |
| 1096 | 282.4 |
| 1046 | 280.3 |
| 1006 | 279.4 |
** Source:
Etheridge, D.M., Steele, L.P., Langenfelds, R.L., Francey, R.J., Barnola, J.-M. and Morgan V.I. 1998. Historical CO2 records from the Law Dome DE08, DE08-2, and DSS ice cores. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tenn., U.S.A.