The sensitivity of the latest Permian climate-carbon state to CO2 emissions in an Earth System Model

The largest mass extinction on Earth with an estimated 90% loss of species occurred at the Permian-Triassic Boundary (~252 Ma). The end-Permian mass extinction coincides with extreme temperature increases and changes in ocean circulation and biogeochemistry. These climate perturbations are associated with carbon emissions linked to Siberian Trap volcanism. Fully-coupled Earth System Models can be applied to investigate the feedbacks and sensitivities of the background latest Permian climate to such carbon emissions. Past studies have focussed on constraining the magnitude of these carbon emissions without examining the sensitivity of palaeo-configured Earth System models designed for modern simulations. We modified a version of the Max Planck Earth System Model v1.2, similar to that used in the 6^th-phase of the Coupled Model Intercomparison Project, to simulate the latest Permian climate-carbon system and use geochemical and palaeobiological proxy data to constrain the boundary conditions of the modelled climate state.
We first characterise the latest Permian climate state before presenting first results on a sensitivity study of the latest Permian climate-carbon state to CO₂ emission pulses. A 100 year global mean 2 m surface air temperature of 17.5°C is simulated, rising up to 34.7°C in the low-latitude continental interior. The continental interior is also largely arid from ~50°N to ~50°S with a total precipitation maximum of 11.1 mm day^-1 at the equatorial boundary of the Tethys and Panthalassic Oceans. The prevailing hydrological regime drives woody single-stemmed evergreens and soft-stemmed plant functional groups to dominate in the dynamic vegetation model. The 100 year global mean surface ocean of the latest Permian illustrates a warm-pool across the equatorial boundary between the Tethys and Panthalassic Oceans with a maximum temperature of 30.2°C decreasing to temperatures as low as -1.9°C near the poles. Surface salinities vary broadly across the global oceans with 100 year global mean values ranging from 22.9, in well-flushed regions of strong freshwater flux, to 48.6, in low-latitude regions of restricted exchange. Large-scale seasonal mixing below 60°S in the Panthalassic Ocean dominates the global meridional overturning circulation. These model data fit within the bounds represented by the available proxy data for the Late Permian. The widespread shallow ocean mixed-layer also restricts recirculation of nutrients, driving a high gross primary production with weak seasonality. Furthermore, regions of seasonal deep mixing correlate with seasonal pCO₂ patterns at high latitudes. I will also present further analyses of the simulated ocean biogeochemical cycles in the Hamburg Ocean Carbon Cycle model with a focus on the novel extended Nitrogen-cycle processes.