MSCA Individual Fellowship to Andrew Merdith – 2021-2023
This project looked at linking the physical rocky Earth with the atmosphere, biosphere and hydrosphere. This was done with a particular focus on the time that complex life first evolved (the Ediacaran period, about 570 million years ago) and then analysing how and why the environment changes from this time to present-day when intelligent life evolved. While such questions have always been burning on inquisitive minds and been subject to numerous studies (and will continue to be so), we decided to approach the problem from a different direction.
My approach was to build a ‘bottom-up’ view of the world, reconstructing the palaeogeographic (i.e. where are the mountain ranges and ocean basins) and palaeotectonic (i.e. where are the subduction zones and mid-ocean ridges) framework of the planet. Because these parameters control the main cooling and warming mechanisms of Earth’s climate, they regulate the temperature and surface conditions. By approaching the problem in this way we were able to concretely link the planet’s evolution, from rocky exterior, to climate, oceans, plants and mountains and life.
In addition to building the framework, the project also put together an open-source and freely available tool to help link all the different building blocks together. This is the pySCION model (a fully pythonic version of the SCION climate-biogeochemical model), a forward carbon-cycle model operating on 10–100 million year timescales. pySCION uses global maps of different palaeotectonic features, such as mountain ranges, locations of continents and oceans, temperature and runoff to estimate Earth’s surface conditions (weathering, temperature, pCO2 etc.). Thus, this model connects the individual work packages of the project into a coherent way to visualise and test Earth’s evolving climate and surface environments.
This work directly touches on many fundamental questions that engage society and people of all ages. Why is Earth habitable? How did life evolve? Why do we have icecaps and mountains and forests and why did they form when they did? Because the work done in this project encompasses multiple Earth ‘spheres’, we can begin to start offering firm answers to these questions grounded in the physical Earth
Andrew Merdith