Notícias .... SCIENCE, Volume 326, Issue 5958 dated December 4 2009

CO₂ and Miocene Climate Change

CREDIT: TRIPATI ET AL.

Atmospheric carbon dioxide is a powerful greenhouse gas believed to be one of the most important determinants of climate. Ice cores provide a detailed and direct record of CO₂ concentrations over the past 800,000 years, but not earlier. Tripati et al. (p. 1394, published online 8 October) report B/Ca measurementsof planktonic foraminifera, from which they can infer atmospheric CO₂ concentrations, for the past 20 million years. The concentration of atmospheric CO₂ was similar to preindustrial values for the past 10 millions years, but between 15 and 20 million years ago, during the warm lower Miocene epoch, CO₂was more abundant, and major climate transitions toward cooler conditions occurred when CO₂decreased substantially.

http://www.sciencemag.org/content/vol326/issue5958/twis.dtl