Global warming and ocean acidification during the Paleocene-Eocene Thermal Maximum
Abstract
The Paleocene-Eocene Thermal Maximum (PETM), a rapid carbon release event 56 million years ago, represents one of the best analogs for exploring the impact of future global warming and ocean acidification. The current understanding of the PETM event relies on paleoclimate proxy data and Earth system models, both subject to large uncertainties. Here we provide a robust reconstruction of the PETM using a novel data assimilation approach. We assimilate proxy data of sea surface temperature and seafloor carbonate sediment content (a measure of ocean acidification) with climate and carbon chemistry output from an intermediate-complexity Earth system model. Our new reconstruction indicates an increase in CO2 from 1240 parts per million (ppm; 95 percent confidence level: 950 1520 ppm) to 2000 ppm (1730 2280 ppm) and a global sea surface temperature rise of 5.2 oC (4.8 to 5.6 oC) during the PETM. These results suggest a much higher climate sensitivity during the PETM than the present-day range (2.34.7 oC per doubling). The PETM is accompanied by a global drop in surface ocean pH of 0.3 units, of similar amplitude to but much slower than projected for the end of the 21st century (middle of the road and high-emissions scenarios), indicating that unconstrained anthropogenic carbon release will cause an ocean chemistry perturbation that is unprecedented in the last 56 million years.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMPP54A..08L