From emissions to climate impacts and back again

This fellowship will develop an open-source and user-friendly simple climate model focusing on the impacts of climate change mitigation. Simple climate models are incredibly useful for providing projections of how global temperatures might change under different greenhouse gas emissions scenarios. Unlike the state-of-the-art climate models run by the Met Office and others around the world, simple models do not need vast amounts of expensive computer resource and time to output results. This means they are powerful tools for supporting policy and decision making on climate mitigation because they provide rapid assessments based on the best available science.

Simple climate models used in climate change mitigation assessments (such as those in the Intergovernmental Panel on Climate Change's Working Group 3 report) only routinely calculate the global mean temperature change since the pre-industrial as a climate change output. While global mean temperature is a useful policy metric and easily communicable, it is a poor description of changes in climate that have the greatest impacts on lives, livelihoods and the economy. Damages and impacts incurred by society and the natural world are typically more sensitive to the severity and frequency of heatwaves, droughts and extreme rainfall, and sea-level rise rather than global average temperature. These outputs are much more relevant for human and natural ecosystems, and further affect crop productivity and health. The research will develop climate impact metrics such as these for use in a simple climate model. This research will allow policymakers to determine the localised benefits of climate change mitigation policies besides the impact on global mean temperature. The model will be made available on a well-documented, interactive website.

This fellowship will also explore the feedbacks between climate change and the energy system, implementing these into integrated assessment modelling for the first time. Future emissions projections that are used to drive simple climate models are often derived from coupled models of the economy and energy system called integrated assessment models (IAMs). Integrated assessment models are tools used to determine pathways to sustainable energy and economic development and to report the climate impact of energy policy decisions. Currently, the link from emissions to climate change in IAMs is in one direction only, where there are real and identified feedbacks from the climate on energy supply and demand (e.g. increased requirements for air conditioning should summer temperatures continue to increase). This fellowship will seek to include these real-world climate impacts on the energy supply into integrated assessment models. When combined with the simple regional impacts climate model, it will provide a much more complete picture of the climate change impacts of energy system decisions. One key focus of this work is that model development will be open-source, settling a demand for increased transparency in integrated assessment modelling.

The project will build collaborative links between the NERC and IIASA research communities, leveraging experience from two IIASA programs (Energy, and Ecosystems Services and Management) and making use of networking building activities facilitated through an identified senior academic in the UK with existing strong IIASA links.

This project is designed to be mutually beneficial to the NERC and IIASA research communities. At IIASA, I will contribute towards their open-source integrated assessment model (IAM) development and contribute knowledge on climate change impacts, bringing skills from climate modelling, energy and software development. In the UK I will develop capacity in energy systems and integrated assessment modelling.

The Intergovernmental Panel on Climate Change (IPCC) will be a key beneficiary of this research. Working Group 1 (WG1) will benefit from an open-source, fully calibrated (to the latest climate model data) simple climate model that will contribute to the Sixth Assessment Report. As a Chapter Scientist in WG1 I will help to shape the report and have influence over its scientific content. My involvement with WG1 will allow me to reach a wide network of fellow scientists at lead author meetings. My advisory panel will allow me to contribute to WG3 with the goal of using the model in climate change mitigation and climate change impact assessments for the emissions pathways provided to AR6. Output from the simple model and software developed in this fellowship will contribute towards the AR6 Scenario Database, a public-facing repository of emissions and temperature projections from all pathways considered by the IPCC (see the AR5 example at https://tntcat.iiasa.ac.at/AR5DB/dsd?Action=htmlpage&page=series). Deepening engagement between working groups is an aim of at AR6 WG3 panel. Through my existing expertise and the work proposal for this fellowship, I am well-placed to make a substantive contribution to this aim.

This research will feed into domestic UK policy by providing a basis for assessing climate impacts from emissions, for example by providing an assessment of how UK climate change policy can affect regional impacts in the UK and further afield. The Priestley International Centre for Climate is well-placed to assist with their links to the Committee on Climate Change and the Department of Business, Energy and Industrial Strategy.

Finally, this research will enable more understanding of the processes driving climate change and climate mitigation amongst students and the interested public. The model will be used for teaching purposes at the University of Leeds, and the interactive website used as a demonstrative tool in public engagement activities.