Insights from a New Carbon Cycle Box Model into the Influence of Tectonics on Cenozoic CO2
Abstract
Proxy data depict a nonmonotonic evolution of CO2 over the Cenozoic, the causes of which are uncertain. One proposed driver is changes in volcanic outgassing driven by changes in tectonics.
In order to quantify the link between tectonics and climate, I have developed a new carbon cycle box model, the Geologically Evolving Carbon Cycle + Ocean (GECCO) model. GECCO explicitly links the subduction of carbonaceous sediment to volcanic outgassing of carbon. This link has the potential to drive large, long term CO2 perturbations through tectonic recycling of carbon. Furthermore, including the link between subduction and volcanic outgassing allows factors that affect ocean carbon burial, such as sea level and lysocline depth, to influence climate on multimillion year timescales. I recreate the Cenozoic CO2 history by applying series of forcings within GECCO, including changes in silicate weatherability, changes in sea level and changes in ice volume. These results show 'CO2 echoes' - oscillations in atmospheric CO2 caused by re-emergence of subducted carbon through tectonic recycling. Tectonic recycling provides a consistent explanation for multimillion year carbon cycle oscillations. I have used GECCO to run an ensemble of Cenozoic simulations, using a variety of tectonic parameters as boundary conditions. The output of this ensemble is compared to proxy CO2 data to identify the range of feasible tectonic parameters. In addition, I have explored the long term climate response to tectonic forcing by modelling transient tectonic changes in GECCO. In summary, GECCO provides a more holistic view of the Cenozoic, by treating long term carbon fluctuations as connected through tectonics, as opposed to individual events. This allows GECCO to recreate the Cenozoic CO2 history with comparatively simple forcings, and to explore the roles tectonics plays in determining palaeo CO2 evolution.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP21D1438W
- Keywords:
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- 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 1616 Climate variability;
- GLOBAL CHANGEDE: 9604 Cenozoic;
- INFORMATION RELATED TO GEOLOGIC TIME