James Zachos, Ph.D.
Professor of Earth & Planetary Sciences
University of California, Santa Cruz
Rapid global warming and ocean acidification
55 million years ago:
Lessons for the future
Wednesday – January 10, 2007
Pacific Forum – 3:00 p.m.
The current anthropogenic perturbation to the global carbon cycle is not unprecedented. Evidence exists in the geologic record of a similar event approximately 55 million years ago at the boundary between the Paleocene and Eocene epochs. This event is characterized by an extreme, but short-lived rise in global temperature, and by massive ocean acidification. One hypothesis attributes these changes to the rapid decomposition of marine hydrates and release of as much as 2000 Gt of methane, a phenomenon that in itself may have been triggered by gradual warming. To test this and other hypotheses, and better characterize the evolution of this unique greenhouse event and its impacts on ocean chemistry, several coring expeditions to the Pacific and Atlantic were undertaken by the Ocean Drilling Program between 2001 and 2005. In this presentation, I will discuss how data collected during these expeditions have provided new insight into several critical aspects of this event including the magnitude and rate of warming, the extent of ocean acidification, and the time scale for recovery.