CLOSER (Closing the Loop: Attribution of Complex Climate Disasters to Climatic and to Policy Changes) advances the science of attribution and forecasting of climate-related disasters. Climate-related extremes — floods, droughts, heatwaves, wildfires — are becoming more frequent and severe, yet the resulting disasters emerge from complex interactions between climate change and other factors such as land-use change, groundwater depletion, and changes in social vulnerability. Current methods cannot fully disentangle this complexity, leaving governments, emergency responders and communities without the full picture they need to act effectively. A key innovation of CLOSER is the expansion of “event attribution” — the science that quantifies how much climate change has contributed to a specific disaster. Today, attribution science can tell us that climate change made a heatwave more likely or a flood more intense, but it cannot yet tell us how much a policy decision, a land management choice, or a change in social vulnerability contributed to the final damage. CLOSER fills this gap by developing a new Protocol for Expanded Attribution and Forecast that traces the full chain of causes behind a climate disaster — from greenhouse gas emissions to local decisions — and links them to real-world impacts on people, ecosystems and economies, across past, ongoing and future events. Working closely with emergency responders, climate services, and policymakers across six real disaster cases on four continents — including Mediterranean droughts, Caribbean hurricanes, floods in Senegal and harvest failures across multiple continents — the project develops practical tools to help decision-makers better