About 55 million years ago, Earth experienced a period of global warming that lasted ~170,000 years (1). This climate event–the Paleocene-Eocene Thermal Maximum (PETM)–may be the best ancient analog for future increases in atmospheric CO2. But how well do we understand this event?
Pagani M., Caldeira K., Archer D., Zachos J. C., 2006. Atmosphere: an ancient carbon mystery. Science 314(5805): 1556. Article.
