Ocean biogeochemistry in paleo climates

We run the Max Planck Institute Earth System Model (MPI-ESM) in specific paleo adjusted configurations in order to better understand global environmental conditions of past climate states. These climates were very different from today as climate changes through time due to several internal and external drivers, e.g., orbital parameters, continental movement, or atmospheric greenhouse gas concentrations. Paleo climate states can serve as test-beds for evaluating processes and responses within the climate models. Within our group the work focuses on the recent past (last 130k years) to study the role of the ocean biogeochemistry for varying levels of atmospheric CO2 during glacial - interglacial cycles. Another focus is the ocean biogeochemistry of past warm climates in Earth’s deep past (i.e., Paleocene-Eocene Thermal Maximum, 55 mil years ago), to study processes in a high CO2 world.

Glacial cycles

There is still little consensus about the mechanisms causing the glacial - interglacial variations in atmospheric CO2 concentrations of around 100 ppm. Some of those mechanisms are driven by alterations in ocean biogeochemical cycles. Hence, it is crucial to understand ocean biogeochemistry dynamics during glacial-interglacial transitions. Our group takes part in the German national climate modeling initiative PalMod, which is aiming at simulating a full glacial cycle (135k – today) in transient mode with a state-of-theart Earth System Model (ESM). Within this framework we address the ocean biogeochemistry, using a comprehensive modeling approach. Our results aim at improving the understanding of glacial – interglacial changes in atmospheric CO2, especially in terms of marine carbon sequestration and release. Our work contributes to developing comprehensive ESMs, which are capable of simulating the climate evolution and the variability during the last glacial cycle.

Contact: Mathias Heinze

Project: PalMod https://www.palmod.de/

Paleocene Eocene Thermal Maximum

The Paleocene–Eocene Thermal Maximum (PETM, 55 mil years ago) is one of the closest analogues for ongoing and future climate change in Earth’s history. This event is characterized by a massive carbon release, which caused a global warming of 5-9°C, within a relatively rapid onset and gradual recovery over 150 kyr. The onset of the event was associated with intense dissolution of marine carbonate sediments and a massive negative δ13C anomaly. We run ESM simulations of the PETM to investigate the long-term response of marine biogeochemistry to ocean dynamical changes. The focus of our research lies on the different response in deoxygenation and ocean acidification between the Atlantic and the Pacific Ocean basins, which can be derived from the proxy record. We test how the PETM ocean biogeochemistry was affected by transient changes in ocean dynamics (driven by changes in ocean circulation and mixing).

Contact: Mathias Heinze

References:

Heinze, M. (2015): Modelling the Carbon Cycle during the Paleocene-Eocene Thermal Maximum. Reports on Earth System Science 165 (Ph.D. thesis).

Heinze, M. & Ilyina, T. (2015): Ocean Biogeochemistry in the warm climate of the Late Paleocene. Climate of the Past, doi:10.5194/cp-11-63-2015, 11, 63-79.