THIS WEEK IN SCIENCE

摘要

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 CO_2 concentrations over the past 800,000 years, but not earlier. Tripati et al. (p. 1394, published online 8 October) report B/Ca measurements of planktonic foraminifera, from which they can infer atmospheric CO_2 concentrations, for the past 20 million years.