The new Earth Observation Science Strategy outlines a vision for ESA Earth science through 2040, which is consistent and coherent with the ESA Strategy 2040. It presents priorities and accompanying approaches that both reflect the need for discovery science, as well as the ability to respond to specific scientific and societal challenges. It identifies the areas of science that ESA needs to respond to, along the full value chain – from the development of innovative Earth Observation missions through to excellent Earth science and uptake of new observations by the user and applications community. At the heart of the Earth Observation Science Strategy, overarching science themes and guiding questions are identified. These encapsulate critical Earth system science issues and knowledge gaps in which Earth observation satellite technology provides a unique contribution, either leveraging existing or near-future data sources or by developing new capabilities and filling observation gaps. The strategy addresses the need to identify and provide a portfolio of science themes and cross-cutting science questions that guide the implementation of Earth observation activities over a range of timescales, some delivering impact and benefits in the short term, and some guiding Earth Observation Programmes activities over the longer term.