Some like it hot: marine algae in warm oceans of the past

Ocean warming already leads to the poleward expansion of key phytoplankton species and significant reductions in net marine primary productivity in the tropics.

Yet, the long-term impacts of poleward shifts in the biogeographic distribution of prominent primary producers, such as changes in global primary production and carbon sequestration in the deep ocean, remain largely unknown.

This project will investigate the impacts of prolonged ocean warmth on phytoplankton composition, their biogeographical distribution and past productivity using scientific ocean drilling legacy data and drill-sites.

We will study the fossil remains of marine algae from the Miocene Climatic Optimum (MCO; 16.9-14.7 Ma), the warmest climate state of the past 24 million years.

Detailed studies of the MCO are important for constraining future warming scenarios, because it was a time interval of sustained global warmth under moderately high atmospheric CO2 levels (400-600 ppm) and a much weaker latitudinal temperature gradient than today. Biogenic sediment burial rates and nannofossil assemblage data will form the backbone of this project.

Data will be mined from existing IODP datasets and new, high-resolution fossil time series will be produced at key sites from low- and high latitudes.

Our empirical results will be compared to global biogeochemical and climate model simulations of the MCO, run by colleagues at the University of Michigan, to mutually verify and validate our independent findings.