Stordal, Frode; Svensen, Henrik; Aarnes, Ingrid; Roscher, Marco
Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 471, p. 96–107, 2017
The Siberian Traps Large igneous province was a key player in the end-Permian extinction and climatic change due to degassing from lavas and heated sedimentary rocks. Although the specific degassing scenarios from the province are debated, this implies that gas release on a timescale tuned to the cooling of lava flows and subvolcanic intrusions (i.e. decades to centuries) must have been sufficient to affect the atmospheric chemistry. Here we test this assumption by using simple box model calculations to constrain century-scale degassing of CO2 and CH4 from high-end volumes of individual lava flows and sills from the Siberian Traps. The model includes gas fluxes of CH4 and CO2, their atmospheric lifetimes and radiative forcing, as well as the climate sensitivity in a global average climate system calibrated to end-Permian time. The fluxes are estimated based on lava degassing and contact aureole volumes and devolatilization during the first 100 years following emplacement. We test the sensitivity to extreme emissions of up to 25 GtC/yr, CH4 fractions from 0 to 100%, wide ranges of climate sensitivities (1.5–6.0 °C for CO2 doubling), pre-event concentrations, and atmospheric lifetimes. We find that the global annual mean temperature perturbation is 7.0 °C in our baseline case using a 10 GtC/yr emission and a 60% CH4 fraction, assuming 4.5 °C as the climate sensitivity. Even for low emission scenarios (0.7–1.2 GtC/yr), the temperature response is ~ 1.5 °C. We conclude that sporadic individual large-scale volcanic events in Large igneous provinces have the potential to cause a strong global warming on very short timescales. In addition to the emission strength, the CH4 fraction and the climate sensitivity have the strongest impact on the century-scale temperature perturbation.