Marine carbon dioxide removal (mCDR) is increasingly recognized as a potential complement to deep emissions reductions in addressing climate change. However, significant uncertainties remain regarding the environmental impacts of many proposed mCDR approaches, and a lack of standardized methods for assessing potential environmental effects can hinder informed decision-making by researchers, project developers, regulators, local communities, and other interested parties. As the field continues to advance, there is a growing need for transparent, scientifically robust approaches to evaluating environmental risks, benefits, and uncertainties across diverse mCDR pathways. The emerging mCDR sector includes a wide range of biological, geochemical, and physical approaches, each with distinct impact pathways, monitoring needs, and uncertainties that must be assessed in a structured and proportionate manner. To address this need, Ocean Visions is leading the development of the first comprehensive Environmental Impact Assessment Framework (EIAF) for mCDR. Following a competitive international selection process, Ocean Visions assembled a multidisciplinary team led by Fugro, in collaboration with Integral Consulting and the UK National Oceanography Centre (NOC), to develop a globally relevant framework that integrates expertise in environmental impact assessment, marine ecology, ocean science, carbon dioxide removal, and ocean governance. The project is engaging stakeholders from around the world to ensure the framework is scientifically rigorous, practical to implement, and relevant across diverse regulatory and geographic contexts. The EIAF draws upon established environmental impact assessment practices from marine industries while addressing the unique challenges associated with emerging mCDR approaches. It provides a structured process spanning screening, scoping, baseline characterization, impact assessment, reporting, review and decision-making, and implementation, monitoring, and management. The framework is designed to support environmental evaluation across a broad range of mCDR technologies and project scales, from early-stage field research to potential future deployment activities. As part of its development, the EIAF is being tested through real-world and hypothetical mCDR case studies to evaluate its practicality, rigor, and utility for environmental decision-making across different pathways and governance contexts. This presentation will describe the development of the framework, highlight key considerations for assessing environmental impacts across mCDR pathways, and discuss lessons emerging from engagement with practitioners, researchers, regulators, and other stakeholders. Particular attention will be given to evaluating impacts under scientific uncertainty, developing assessment approaches that remain adaptable across jurisdictions, and supporting transparent and accessible environmental review processes.