Observed, Strategic, sustained action is now needed to avoid further negative consequences of climate change and to build a greener, cleaner and fairer future. According to the Intergovernmental Panel on Climate Change the rise in global temperature is largely driven by total carbon dioxide emissions over time. In order to avoid further global warming, international Governments agreed to work towards a balance between emissions and greenhouse gas removal (GGR), known 'net zero', in the Paris Agreement. In June 2019 the UK committed to reaching net zero emissions by 2050, making it the first G7 country to legislate such a target. Transitioning to net zero means that we will have to remove as many emissions as we produce. Much of the focus of climate action to date has been on reducing emissions, for example through renewable power and electric vehicles. However, pathways to net zero require not just cutting fossil fuel emissions but also turning the land into a net carbon sink and scaling up new technologies to remove and store greenhouse gases. This will require new legislation to pave the way for investment in new infrastructure and businesses expected to be worth billions of pounds a year within 30 years. This challenge has far-reaching implications for technology, business models, social practices and policy. GGR has been much less studied, developed and incentivised than actions to cut emissions. The proposed CO2RE Hub brings together leading UK academics with a wide range of expertise to co-ordinate a suite of GGR demonstration projects to accelerate progress in this area. In particular the Hub will study how we can (1) reduce technology costs so that GGR becomes economically viable; (2) ensure industry adopts the concept of net zero in a way that will maintain and create jobs; (3) put in place sensible policy incentives; (4) make sure there is social license for GGR (unlike fracking or nuclear); (5) set up regulatory oversight of environmental sustainability and risks of GGR; (6) understand what is required to achieve GGR at large scale and (7) guarantee there are the skills and knowledge required for all this to happen. Building on extensive existing links to stakeholders in business, Government and NGOs, the Hub will work extensively with everyone involved in regulating and delivering GGR to ensure our research provides solutions to strategic priorities. We will also encourage the teams working on demonstrator technologies to think responsibly about the risks, benefits and public perceptions of their work and consider the full environmental, social and economic implications of implementation from the outset. CO2RE will seek to bring the GGR community in the UK as a whole closer together, functioning as a gateway to UK inter-disciplinary research expertise on GGR. We will inform, and stay informed, about the latest developments nationally and internationally, and reach out to engage the wider public. In doing so we will be able to respond to a rapidly evolving landscape recognising that technical and social change are not separate, but happen together. To accelerate and achieve meaningful change, we will be guided by consultation with key decision-makers and the general public, and set up a £1m flexible fund to respond to priorities that emerge with the help of the wider UK academic community. Ultimately we will help the UK and the world understand how GGR can be scaled up responsibly as part of climate action to meet the ambition of net zero.

In 2015, global passenger and freight commercial aircraft accounted for 866 million tonnes or 2.7% of energy use-related CO2 emissions, which is more than twice the amount released by the entire UK economy. If air passenger and freight revenue tonne-km (RTK) continue to grow at around 4.5% per year and aircraft fleet fuel use per RTK continues to decline by 2% per year, the projected stronger growth in RTK would lead to an increase in CO2 emissions by 2.5% per year, a doubling by 2050. This growth trend in CO2 emissions is in strong contrast to global efforts to reduce economy-wide CO2 emissions as mandated by the Paris Agreement. Whereas simple arithmetic implies that a net zero-carbon aviation system can only be achieved through disruptive aircraft technologies and fuels, its most cost-effective composition remains unclear. Such knowledge is critical as vast investments will be required by aircraft manufacturers, fuel suppliers, airlines and airports to accomplish the transition. In addition, transitioning towards a net zero-carbon aviation system requires understanding the underlying technology roadmap, complemented by enabling policy measures and identification of early adopters. At the same time, the multiple time lags in the aviation system, from developing an early concept to fleet adoption of the final product, in addition to the long lifetime of commercial aircraft in the order of 25 years, demand swift action to generate a significant impact by mid-century. This, in turn, requires that all CO2 mitigation options are considered, including travel demand management, which necessitates an improved understanding of travel behaviour. The TOZCA project will develop a comprehensive tool suite to simulate the most cost-effective transition toward a net zero-carbon aviation system by 2050 and a later 2070 date. Using this tool suite, the TOZCA project will identify the technological, economic and environmental synergies and trade-offs that result from drastic CO2 emissions reductions through changes in technology, fuels, operations, use of competing modes and change in consumer behaviour.