Potential links between continental rifting, CO2 degassing and climate change through time

The concentration of CO 2 in the atmosphere is a key influence on Earth’s climate. Today, significant quantities of CO 2 are emitted at continental rifts, suggesting that the spatial and temporal extent of rift systems may have influenced deep carbon fluxes and thus climate change throughout geological time. Here we test this hypothesis by conducting a worldwide census of continental rift lengths over the last 200 million years. We estimate tectonic CO 2 release rates through time and show that along the extensive Mesozoic and Cenozoic rift systems, rift-related CO 2 degassing rates reached more than 300% of present-day values. Using a numerical carbon cycle model, we find that two prominent periods of enhanced rifting 160 to 100 million years ago and after 55 million years ago coincided with greenhouse climate episodes, during which atmospheric CO 2 concentrations were more than three times higher than today. We therefore propose that continental fragmentation and long-term climate change could plausibly be linked via massive CO 2 degassing in rift systems. Degassing of large amounts of CO 2 from continental rifts may have contributed to greenhouse climate episodes over the past 200 million years, according to numerical models.