Graph of atmospheric carbon dioxide over thousands of years before 1950

Atmospheric carbon dioxide and temperature data derived from Antarctic ice core measurements for the past 800,000 years. The Keeling Curve is the vertical segment appended to the ice core data at the upper right.

Reprinted with permission from Harris, D. C., Charles David Keeling and the Story of Atmospheric CO2 Measurements. Anal. Chem. 2010, 82 (19), 7865-7870, using data from Lüthi, D.; Le Floch, M.; Bereiter, B.; Blunier, T.; Barnola, J.-M.; Siegenthaler, U.; Raynaud, D.; Jouzel, J.; Fischer, H.; Kawamura, K.; Stocker, T. F. Nature 2008, 453, 379–382.