Cenozoic’s Warmest Period Shows Elevated Levels of Atmospheric Carbon Dioxide

Mineralogic evidence shows that the period with highest prolonged global temperatures in the last 65 million years had ultra-elevated concentrations of atmospheric carbon dioxide, according to new research in the 29 September 2006 issue of the journal Science.

The finding supports a causal connection between atmospheric carbon dioxide and global warmth, the authors say.

Tim K. Lowenstein and Robert V. Demicco of State University of New York at Binghamton in Binghamton, N.Y., studied the mineralogic evidence from the early Eocene Era—between 56 and 49 millions years ago—and determined that the concentration of carbon dioxide was greater than 1,125 parts per million by volume. That is four times the level of carbon dioxide in the preindustrial age.

Some researchers estimate that Earth's carbon dioxide level could reach about 1,000 parts per million in the next 100 years if the fossil fuels continue to power the world.

The researchers based their estimates of ancient carbon dioxide during the Eocene and Miocene eras on the sodium carbonate minerals precipitated from waters in contact with the atmosphere, using samples from deposits in Colorado, Wyoming, China, and Turkey.

Benjamin Somers

28 September 2006