Modelling Aviation Global climate Impacts from Contrails and Aerosols (MAGICA)

Current best estimates indicate that aviation contributes ~5% to global warming, with a significant proportion caused by non-CO2 effects. The largest of these non-CO2 effects is due to contrail cirrus, which also have the largest associated uncertainty. Another important effect is likely to be caused by aerosol-cloud interactions, although to date, due to the substantial challenges to simulate it in models, there are no best estimates for this effect. With several ambitious targets having been set for aviation to reduce its climate impact, there is an urgent need to improve our understanding of this impact today, together with developing reliable models suitable to advise on the most appropriate mitigation options.

This project will make substantial advances in reducing the current uncertainty in aviation non-CO2 climate impacts by addressing its two largest sources: contrail cirrus and aerosol-cloud interactions. A major limiting factor in reducing the large uncertainty in these two aviation climate impact terms is the fact that only two climate models are currently able to simulate them, the German ECHAM and the American CESM models. Moreover, they employ very different methodologies, making identifying their main sources of uncertainty very challenging.

Building on our team's expertise, we will further develop the capabilities of the UK Met Office climate model to simulate both contrail cirrus and aerosol-cloud interactions with methodologies consistent with both ECHAM and CESM. This will allow us for the first time to consistently quantify and compare these two important aviation climate effects in different climate models. In addition, we will also quantify how they are likely to change for a range of future aviation scenarios consistent with Net Zero CO2 strategies, including the use of alternative fuels (e.g. Sustainable Aviation Fuel and hydrogen), kerosene with direct air capture and storage, and contrail avoidance strategies. To develop these realistic scenarios, we will use our team's unique global aviation systems model which is able to account for aircraft operations developments, together with examining how they may change in the future given the current pledges and other system trends. Finally, we will explore and assess the most efficient technological and air traffic management solutions using our FaIR climate model emulator, one of only two calibrated probabilistic climate models used across the latest IPCC assessment report to quantify the global temperature response to emission scenarios.

By making significant advances in our ability to robustly quantify the two largest sources of uncertainty in aviation climate impacts, our project will directly guide future aviation technology solutions by informing both policymakers and industry on the best future policy and investment decisions. Throughout the project, we will engage regularly with our project partners and other key stakeholders, including aircraft and jet engine manufacturers, airlines, government departments/agencies, and NGOs.