Assessing the spatial expansion of plants in an Earth System model

The emergence of land plants and their expansion across the Earth's surface has helped shape the climate of the Phanerozoic. Land plants are a major contributor to global photosynthetic biomass which in turn influences atmospheric CO₂ and O₂ levels. They also amplify continental weathering processes, which are a critical component of many global biogeochemical cycles. The inclusion of spatially-resolved vegetation within climate-biogeochemical models that predict paleo-CO₂ and O₂ levels can create a more accurate picture of the paleo-Earth [Gurung et al., in revision], however these applications have been limited by the availability of climate model simulations at high time resolution, which makes continuous spatial modelling difficult. Here, we use a new machine learning approach [Zheng et al., in revision] to build a 1-Myr climate emulator for the SCION climate-biogeochemcial model, and couple this to a deep-time vegetation model [FLORA; Gurung et al., 2022]. This allows us to re-run the plant colonisation of the land over the Paleozoic in detail and to view the global impact of changes in land occupation and productivity between early and more complex plants. By integrating simplified evolutionary and competition dynamics into the model, we can compare the effects on weathering, carbon burial and climate to help us better understand the dynamics that influence the expansion of plants and the resulting long-term Earth system changes.

Gurung et al., Climate windows of opportunity for plant expansion during the Phanerozoic Nat Comms 13 (2022)