Science plays a vital role in addressing global environmental challenges, yet research and research-related activities themselves carry a significant environmental footprint. This evidence-informed briefing provides a comprehensive overview of the environmental impacts of research across disciplines and activities, from infrastructures and laboratories to travel, procurement, and computing. It explains why environmental sustainability must be treated as a core value of research organisations, not only to reduce environmental harm, but also to deliver wider organisational and societal benefits, including economic efficiency, safety, credibility, and reputational gains. Developed by Science Europe, this briefing supports the implementation of the Framework for the Environmental Sustainability of Research Organisations and aligns with the organisation’s Vision for Research Cultures. It is intended as a practical and informative resource for Science Europe Member Organisations, research organisations, researchers, and policymakers committed to making science more sustainable, competitive, and aligned with the objectives of the European Green Deal and the Sustainable Development Goals.