Decarbonizing the production and consumption of products and materials play a critical role in reaching ambitious climate targets. As a result, a new circular economic system that aims to reduce primary material use (in addition to energy efficiency and fuel shifts) can address both Greenhous Gas emissions (GHG)s and increase resource efficiency. However, current GHG mitigation models and scenarios that inform climate policymakers do not generally include circular economy (CE) options. They also do not cover the possible synergies of the CE with other societal goals such as the Sustainable Development Goals (SDGs), nor the challenges involved in rearranging value chains and consumer behaviour. CIRCOMOD addresses these challenges by developing a new generation of advanced models and scenarios that will assess how CE can reduce future GHGs and material use. The project brings together a unique consortium of leading research teams from different disciplines, including industrial ecology and material flow modelling, process-oriented integrated assessment modelling, and macro-economic modelling. It aims for a breakthrough in integrating CE and GHG mitigation assessments by developing an analytical framework that maps circular economy strategies to existing influential climate scenarios; by providing robust and timely CE data in an open repository; and, by improving the representation of the CE in leading models used by European and global institutions, while strengthening links between the models. These key scientific breakthroughs enable robust scientific assessments in collaboration with stakeholders across policy and industry. It will provide timely input to international assessments such as the Intergovernmental Panel on Climate Change (IPCC) and the International Resource Panel (IRP). CIRCOMOD will provide actionable insights into the circular economy and help address one of the largest challenges of the coming decades.