New Frameworks for Constraining Atmospheric Carbon Dioxide through Marine Algal Proxies

Ann Pearson, Harvard Faculty of Arts and Sciences

Better estimates of past carbon dioxide levels in the atmosphere (pCO2) are critical to the advancement of climate science. This workshop will gather selected colleagues who recently, either independently or in collaborative groups, have made significant contributions to improving one of the major proxies used for this effort: lipids of marine algae. The approach is based on the different chemical behavior of the stable isotopes of carbon, a signal that can be preserved in organic molecules stored in seafloor sediments for millions of years. While initially developed as a climate reconstruction tool more than 30 years ago, current research has revealed several discrepancies between observed proxy behavior and what would be predicted from the underlying theory. Efforts to tackle this emerging problem are beginning to converge on a common set of explanations and appear ready to envision the future route forward. The goal of the present workshop is to produce a transformative paper, coauthored by all participants, that establishes a new baseline theory for pCO2 reconstructions based on marine algal lipids and identifies the essential remaining questions, and how to answer them, as targets for future research.