Towards integrated models of mantle convection, surface dynamics and climate evolution

The long-term evolution of the biosphere on Earth is tightly coupled to changes in the geosphere and climate. Investigating the evolution of Earth’s climate over the course of the Phanerozoic and beyond requires extensive numerical modelling efforts. Classically, this has been done using Earth System Models of varying complexity. While these models are well-suited to simulate a majority of processes in the ocean, the atmosphere and on the land surface, they lack a key component of the Earth system ―  the interior. Processes in the mantle drive plate tectonics on Earth and by means of degassing are a key factor in determining the atmospheric CO₂ concentration, influencing biological evolution. Both, the position of continents as dictated by plate tectonics as well as the concentration of greenhouse gases in the atmosphere are known to be crucial in shaping Earth’s climate. An important suite of mechanisms that influences both climate and mantle can be found in silicate weathering, the erosion of weathered material and its transport and sedimentation in subduction zones. The influx of sediments into subduction zones has been shown to alter the rheology of the subduction slab, influencing the speed of subduction and chemistry of the slab and thereby impacting mantle convection processes (e.g. Bello et al., 2015). Here, we present a framework for coupling the new PANALESIS paleogeographic reconstruction (Vérard, 2019) to an Earth System Model of Intermediate Complexity (EMIC) and the mantle convection model with plate tectonics based on StagYY code. This is done using climate output from the EMIC to force a landscape evolution model that is used to compute sediment influx into subduction zones. Degassing rates obtained from the mantle convection simulations are then used to assess atmospheric CO₂ levels and create climate lookup tables for different degassing scenarios. These data can then be used to force a temporally continuous carbon cycle model to update previous pCO₂ curves for the Phanerozoic and beyond. Given the new paleogeographic reconstruction and the more sophisticated modelling framework, this approach may give new insights into the long-term interactions between mantle and climate and the consequences for biological evolution.

References

Bello, L., Coltice, N., Tackley, P. J., Müller, R. D., & Cannon, J. (2015). Assessing the role of slab rheology in coupled plate-mantle convection models. Earth and Planetary Science Letters, 430, 191-201.

Vérard, C. (2019). PANALESIS: Towards global synthetic palaeogeographies using integration and coupling of manifold models. Geological Magazine, 156(2), 320-330.