Caldeira Lab Research:Paleoclimate and geochemical cycles

An Ancient Carbon Mystery

Mark Pagani, Ken Caldeira, David Archer, & James C. Zachos

An investigation of the cause of a massive global warming event 55 million years ago.

Pagani, M., K. Caldeira, D. Archer and J.C. Zachos, An ancient carbon mystery. Science 314, 1556-1557, 2006.

Atmospheric carbon concentration during the PETM (Paleocene-Eocene Thermal Maximum): Carbon dioxide levels millions of years ago were much higher than they are today. The temperature rise that happened then would require carbon levels of up to 30000ppm.


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?