Efficient Emulation of Earth System Processes for Adaptation and Mitigation

Climate model emulators are simplified representations of more complex climate models and are becoming increasingly important to the IPCC. This is because emulators can be run quickly, much faster than complex Earth System models (ESMs), and flexibly, for example to be set up to replicate the large-scale behaviour of existing ESMs. This means they can be run probabilistically to sample the full range of uncertainty in future climate change and be applied to any conceivable emissions scenario and not just the handful of Shared Socioeconomic Pathways (SSPs) that are analysed in ESMs. The Finite-amplitude Impulse Response (FaIR) emulator was used in the IPCC's Special Report on 1.5 degrees Celcius (2018) and Sixth Assessment Report for the contributions of Working Group 1 (2021) and Working Group 3 (forthcoming in 2022) to provide global mean temperature and radiative forcing projections, and can easily be adapted to sea-level rise.

This project will develop FaIR by including Earth System feedbacks that are not currently present in the model, such as permafrost, methane wetlands and the nitrogen cycle. This will involve analysing simulations from Earth System models and determining a simple framework that can adequately replicate these behaviours. The importance of these individual feedbacks can be assessed by comparing the outputs to the database of scenarios provided in the IPCC Working Group 3 that focuses on pathways to mitigate climate change. In addition, in order to provide policy-relevant science, FaIR can be coupled to a regional emulator to determine the risks of extreme weather events in important world regions under different levels of warming.

This studentship will link closely with and feed into Met Office projects and goals, including the Hadley Centre Climate Programme. The project will directly contribute to developing the Met Office's simple climate modelling capability to be able to provide rapid assessment of new scenarios designed to meet Paris agreement targets. Under the project, the student will use software development best practices to develop the model. As part of the CASE programme there is the opportunity to spend time at the Met Office to work directly with the Met Office Climate Impacts Team. There may also be potential to collaborate with external partners in Switzerland and Austria on linking the emulator to integrated assessment models.