- MSI 1302
Title: Climate and biogeochemistry in a high CO2 world
Abstract: The geological record can provide valuable information about the operation of the Earth system in an equilibrium high pCO2 world. In this seminar I will show two examples of how molecular fossils (biomarkers) can inform us about past dynamics of Earth’s system. First I will demonstrate how biomarkers can be used to reconstruct changes in atmospheric CO2 during Oceanic Anoxic Event 1a, one of the largest perturbations of the climate system during the last 250 million years. I will show that atmospheric CO2 increased gradually during this event on time scales of hundreds of thousands of years. Despite earlier claims, these results demonstrate that OAE 1a was not associated with wide spread surface ocean acidification nor did this drive the observed turnover in marine calcareous nannoplankton.
Secondly, I will present my recent work on the development of novel organic geochemical temperature proxies. I then apply these novel proxies to the early Paleogene, the warmest period of the last 65 million years. I will show that surface temperatures during thi period of high CO2 were much higher than previously thought with tropical temperatures reaching far into the mid/high latitudes. These results reinstate the debate about early Paleogene temperatures by demonstrating that temperatures were not only much higher than present at mid/high latitudes but could have been tropical, results that can be used to constrain the next generation of climate models.