Abstract
The end-Permian mass extinction event (∼252 Mya) is associated with one of the largest global carbon cycle perturbations in the Phanerozoic and is thought to be triggered by the Siberian Traps volcanism. Sizable carbon isotope excursions (CIEs) have been found at numerous sites around the world, suggesting massive quantities of 13C-depleted CO2 input into the ocean and atmosphere system. The exact magnitude and cause of the CIEs, the pace of CO2 emission, and the total quantity of CO2, however, remain poorly known. Here, we quantify the CO2 emission in an Earth system model based on new compound-specific carbon isotope records from the Finnmark Platform and an astronomically tuned age model. By quantitatively comparing the modeled surface ocean pH and boron isotope pH proxy, a massive (∼36,000 Gt C) and rapid emission (∼5 Gt C yr-1) of largely volcanic CO2 source (∼-15%) is necessary to drive the observed pattern of CIE, the abrupt decline in surface ocean pH, and the extreme global temperature increase. This suggests that the massive amount of greenhouse gases may have pushed the Earth system toward a critical tipping point, beyond which extreme changes in ocean pH and temperature led to irreversible mass extinction. The comparatively amplified CIE observed in higher plant leaf waxes suggests that the surface waters of the Finnmark Platform were likely out of equilibrium with the initial massive centennial-scale release of carbon from the massive Siberian Traps volcanism, supporting the rapidity of carbon injection. Our modeling work reveals that carbon emission pulses are accompanied by organic carbon burial, facilitated by widespread ocean anoxia.
Highlights
| | end-Permian mass extinction compound specific carbon isotopes | CO2 Earth system model northern Norway on the Eastern Barents Sea shelf, hosting an expanded shallow marine section where two drill cores were collected (7128/12-U-01 and 7129/10-U-01) spanning the Permian–Triassic transition (Fig. 1)
Atmospheric CO2 levels following the initial pulse of Siberian Traps volcanism and across the end-Permian mass extinction (EPME) remain poorly known [23, 24], limiting our understanding of the climate feedbacks that occur upon greenhouse gas release during this time
By comparing observed data to results from an isotope-enabled Earth system model, we find that a massive and rapid, predominantly volcanic CO2 emission during the Siberian Traps volcanism is likely the trigger for the carbon isotope excursion and the severe mass extinction
Summary
| | end-Permian mass extinction compound specific carbon isotopes | CO2 Earth system model northern Norway on the Eastern Barents Sea shelf, hosting an expanded shallow marine section (paleo-water depth roughly 50 to 100 m) where two drill cores were collected (7128/12-U-01 and 7129/10-U-01) spanning the Permian–Triassic transition (Fig. 1). Atmospheric CO2 levels following the initial pulse of Siberian Traps volcanism and across the EPME remain poorly known [23, 24], limiting our understanding of the climate feedbacks that occur upon greenhouse gas release during this time To address this critical gap in our knowledge, we constrain the source, pace and total amount of CO2 emissions using an Earth system model of intermediate complexity (i.e., carbon centric-Grid Enabled Integrated Earth system model [cGENIE]; SI Appendix) forced by new astronomically tuned δ13C records from wellpreserved lipid biomarkers preserved in sediments from the Finnmark Platform, Norway. The Finnmark sedimentary records enable the reconstruction of individual yet directly comparable carbon isotope records for the terrestrial and the marine realm that can be astronomically tuned and used to quantitatively assess the source, pace, and total amount of 13C-depleted carbon released during the Siberian Traps eruption that led to the EPME. The directly comparable records of δ13C for the atmosphere and the ocean offer further insights into the size of the true CIE and rate and duration of carbon emissions
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