Fossil marine plankton and future climate change
The goals of this project are to understand how phytoplankton in the polar regions responded to, and may have contributed to climate change between ca 30-40 million years ago. This information should help us understand how phytoplankton may behave, and influence climate in the near future, due anthropogenic global warming. It is difficult to predict future plankton behavior solely from our historical knowledge of living plankton behavior or their biology, as the magnitude of future climate change far exceeds anything that occurred in the historical past, and will produce ocean conditions in polar regions that were last seen on earth only many millions of years ago.
A specific target of our study are the marine diatoms, a phytoplankton group that plays a key role in removing carbon dioxide from the earth's atmosphere. This group is known to have evolved rapidly and increased in abundance close to the time when the earth cooled and polar ice-sheets formed around 34 million years ago. We are also using biogeographic patterns in radiolarians, a zooplankton group common in polar regions, and with species distributions that closely track ocean water masses, to reconstruct changes in the extent of polar oceans. Several other fossil and geochemical measurements that indicate how intensely the oceans were capturing carbon are also being collected (stable isotopes of carbon, oxygen and nitrogen, benthic foraminifera abundances, etc). Substantial effort is also being given to improving the quality of the chronostratigraphy of the deep sea drilling sites we are taking our samples from. All data will be placed in context by developing computer simulations of ocean circulation, plankton productivity and carbon capture. A last, but very important goal is to at least indirectly estimate the risk that several modern, cold water adapted diatom species that are disporportionately responsible for carbon capture might actually go extinct due to the loss of suitable cold-water habitats in future warmer oceans. We are examining the response of past diatom species to major climate change to estimate how much environmental change is tolerated before species actually become extinct.
The project is led by 3 people: Gayane Asatryan (designated PI, lead work on radiolarians), David Lazarus (chronostratigraphy/sampling; formal administration, and senior advisor), and Johan Renaudie, with lead responsibility for data synthesis and the ocean modelling module. Two doctoral students are also part of the team. Gabrielle Rodrigues de Faria is working with carbonate microfossils and geochemistry to reconstruct past physical ocean conditions, and Volkan Özen is doing the primary work on the diatoms. The project is funded via the 'Make Our Planet Great Again' [MOPGA] special program of the DAAD and runs from July 2018 to June 2022.