Dynamics and variability of the Late Permian climate-carbon state in an Earth System Model

The Late Permian climate is the background state for the climate perturbations which lead to the
Permian-Triassic Boundary (~252 Ma). The Permian-Triassic Boundary mass extinction is well established as
the largest of Earth’s mass extinctions with an estimated 90% loss of species. Climate perturbations linked to
carbon emissions from Siberian Trap volcanism are attributed as the drivers of the mass extinction through
extreme temperature increases and changes in ocean circulation and biogeochemistry. Fully-coupled Earth
System Models are required to investigate the sensitivities and feedbacks of the system to these widespread
climate perturbations. The Late Permian climate is simulated with a modified 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.
Geochemical and palaeobiological proxy data are used to constrain the boundary conditions of the modelled
climate state.
The simulated Late Permian climate state is characterised by a 100 year global mean 2 m surface air
temperature of 19.7°C, rising up to 37.7°C in the low-latitude continental interior. Prevailing 100 year global
mean total precipitation patterns indicate that the continental interior was largely arid from ~50°N to ~50°S and
a rainfall maximum of up to 6.5 mm day^-1 is present at the equatorial boundary of the Tethys and Panthalassic
Oceans. Dynamic terrestrial vegetation in the model is dominated by woody single-stemmed evergreens and
soft-stemmed plant functional groups. The 100 year global mean surface ocean of the Late Permian illustrates
a warm-pool across the equatorial boundary between the Tethys and Panthalassic Oceans with a maximum
temperature of 31.7°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 21.9, in well flushed regions
of strong freshwater flux, to 49.2, 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. Additionally, I will
present first results of the ocean biogeochemical state in the Hamburg Ocean Carbon Cycle model with an
extended Nitrogen-cycle. I will also illustrate the results of our investigation into the influence of the Late
Permian monsoon variability on the terrestrial vegetation and ocean carbon cycles.