Columbia University
2011-2012 Distinguished Lecturer
Estimating Cenozoic Atmospheric CO2 and Ocean Carbonate Chemistry

Climate variations of the Cenozoic are often thought to be driven or amplified by changes in greenhouse gas concentrations, but direct measurements can only be obtained from ice cores covering the past 800 ky. Estimating CO₂ beyond this time requires a better understanding of Earth’s carbon reservoirs, and in particular the dynamics of the ocean carbon system. Deep-ocean drilling has recovered sediments throughout the Cenozoic Era and the chemical composition of fossil remains of marine organisms archived in those sediments allows us to gain information of past variations in ocean chemistry. However, reconstructions of past ocean conditions are only as good as our understanding of the proxies that we interpret to reflect those conditions.

Much of my research is based on the validation of chemical proxies in marine carbonates such as planktic and benthic foraminifers, and I specifically focus on the boron isotope and B/Ca proxies for seawater-pH. The observations that we have made from culture experiments with planktic foraminifers and fossil specimens from deep-ocean sediments allow us to improve paleoreconstructions beyond ice core records and to evaluate the reliability of different reconstructions through time. I will present a comparison of surface and deep ocean carbonate chemistry estimates from various time intervals of the Cenozoic, from different proxies and methods, and study similarities and differences.

Dr. Hönisch’s research relies on sediments collected by the ocean drilling programs, with emphasis on those spanning the Cenozoic era.

October 7, 2011: Case Western Reserve University
November 4, 2011: University of San Diego
January 13, 2012: University of South Florida
February 2-3, 2012: Rice University
February 2-3, 2012: University of Houston
February 24, 2012: Binghamton University, SUNY
April 30, 2012: University of New England