Presentation
The pace of anthropogenic climate change shows no signs of slowing down. The latest IPCC report highlights that every compartment of the Earth System is impacted by the catastrophic consequences of anthropogenic climate change. In the ocean, one major consequence is the loss of oxygen, which has been measured for decades and raises pressing concerns about marine resources, but model projections of future ocean deoxygenation are notoriously uncertain.
Fortunately, studying past occurrences of rapid climate warming and marine oxygen stress provides us with a unique mean to draw constraints on potential thresholds in the Earth system and to gain insights on model ability to reproduce the consequences of such changes. In this project, we specifically focus on a tailored episode of brutal climate warming: the Paleocene-Eocene Thermal Maximum (56 Ma). Apart from the pace of change, this event indeed shares striking similarities with the anthropogenic climate change: 1) it is a perturbation exclusively driven by carbon input in the surficial reservoirs of the Earth; 2) it is geologically instantaneous, as carbon is input in the atmosphere and ocean in less than 20 kyrs (best guess 6 kyrs); 3) estimates of added carbon are of the same magnitude as RCP8.5 projections at the 2300 horizon; 4) redox proxies document a global deoxygenation. Because of these characteristics, the PETM has fostered the recovery of numerous archives and is perhaps the most-well covered interval of pre-Quaternary climates. We propose, for the first time, to use an Earth System Model of complexity and resolution close to those used in recent CMIP exercises to investigate the transient dynamical, biogeochemical and oxygen responses to the PETM. Unique lessons about CMIP-class model’s ability to simulate rapid warming perturbations are expected to emerge from the results and to inform the next generation of models used to project our future.
Funding: ANR JCJC
PI: Jean-Baptiste Ladant