ScienceDaily (Dec. 21, 2009) — The kinds of increases in atmospheric carbon dioxide taking place today could have a significantly larger effect on global temperatures than previously thought, according to a new study led by Yale University geologists.

Power plant. The kinds of increases in atmospheric carbon dioxide taking place today could have a significantly larger effect on global temperatures than previously thought. (Credit: iStockphoto/Zsolt Bicz)

Their findings appear December 20 in the advanced online edition of Nature Geoscience.

The team demonstrated that only a relatively small rise in atmospheric carbon dioxide (CO2) was associated with a period of substantial warming in the mid- and early-Pliocene era, between three to five million years ago, when temperatures were approximately 3 to 4 degrees Celsius warmer than they are today.

Climate sensitivity — the mean global temperature response to a doubling of the concentration of atmospheric CO2 — is estimated to be 1.5 to 4.5 degrees Celsius, using current models.

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