The current generation of Earth System Models (ESMs) provides an important scientific basis to understand climate change and inform policy action, both with respect to mitigation and adaptation to global change. However, ESMs need further development to reach their full potential to thoroughly design and assess options necessary to meet the goals of the Paris Agreement (PA), including the environmental impacts of both the mitigation pathways themselves and climate change associated with these pathways.<br/><br/>ESM2025 will develop such a new generation of ESMs through: (1) improving their representation of climate and biogeochemical cycles, using state-of-the-art observations, detailed theory and advanced machine learning techniques; (2) implementing new interactions and couplings between different components of the Earth system, enabling ESMs to run using emissions of major anthropogenic greenhouse gases (CO2, CH4 and N2O), aerosols and their precursors, delivering an unprecedented holistic modelling framework to simulate future Earth system changes; (3) co-developping an innovative framework for linking Integrated Assessment Models (IAMs) and ESMs through improved consistency of their respective representations of climate and land-use, enabling the development of geophysically-sound mitigation pathways.<br/><br/>To achieve these objectives, ESM2025 brings together a world-leading team of experts in Earth system modelling, model evaluation and feedback analysis, IAMs, reduced complexity carbon-cycle climate models, climate education and science-policy communication, all working towards a common goal of developing and assessing robust pathways for realizing the PA. The new generation of ESMs and IAMs will maintain Europe at the forefront of international efforts to model the Earth system and provide invaluable support to European climate policy and climate-related educational activities, as well as to climate services and future IPCC assessments.