Initial assessment of the carbon emission rate and climatic consequences during the end-Permian mass extinction

Numerous lines of geochemical and stable isotopic evidence indicate that the end-Permian mass extinction was accompanied by abrupt climate change induced by CO₂ addition. Catastrophic end-Permian Siberian volcanism may have released a large amount of CO₂ into the atmosphere and pushed the Earth's system beyond a critical threshold, causing the mass extinction. However, the injection rate, total amount and source of CO₂ are largely unknown. We conducted a suite of simulations using the recently published carbon isotope records and U-Pb ages from Meishan section in Zhejiang province, China. An Earth System Model of Intermediate Complexity (cGENIE; http://www.genie.ac.uk) was used to extract the pattern of CO₂ release needed to replicate the observed carbon isotope excursion across the Permian-Triassic boundary. This analysis leads us to suggest that the source of CO₂ must have been significantly heavier than typical biogenic or thermogenic methane to explain the significant warming that occurred during and after the extinction event. Nevertheless, as with the Paleocene-Eocene Thermal Maximum, end-Permian rates of CO₂ addition were likely small compared with modern fossil-fuel burning, but considerably more protracted, such that the likely total CO₂ emitted significantly exceeded the modern fossil-fuel reserves. Peak emission rates corresponded to the onset of the maximum extinction interval, consistent with carbon cycle disruption, including volcanogenic CO₂-induced warming (and perhaps ocean acidification), as a trigger for the end-Permian mass extinction.