Methods and technologies for impact-based early warning of weather and geo-hazards: Overview and perspectives for multi-risk integration

This article overviews methods and technologies underpinning impact-based early warning systems for weather and geo-hazards, with the objective of evaluating the feasibility and principal challenges of their effective implementation within future multi-risk frameworks, with attention to the European context. Adopting an expert-driven overview approach, the paper synthesizes representative methods, operational practices, and technological solutions implemented or under development across weather hazards, including fluvial and flash floods, windstorms, storm surges, heatwaves, droughts, and wildfires, and geo-hazards, including earthquakes, volcanoes, tsunamis, and landslides. For each hazard domain, the review considers forecasting or rapid-response methods, observational and modelling requirements, warning dissemination practices, technological maturity, and end users served. The analysis highlights heterogeneity in lead times, spatial scales, data availability, uncertainty treatment, and institutional organization, ranging from seconds for earthquake early warning to weeks or months for drought monitoring and outlooks. At the same time, common methodological foundations emerge across hazard communities, particularly the coupling of hazard information with exposure and vulnerability data, the increasing use of probabilistic forecasting and machine-learning tools, and the central role of user-oriented communication and decision support. Within Europe, these shared aims coexist with fragmented governance arrangements, uneven operational maturity, and challenges in transnational coordination across meteorological, hydrological, geological, and civil protection communities. Building on this comparative overview, the paper discusses the main barriers to the implementation of integrated impact-based and multi-risk warning capabilities, including fragmented data environments, limited interoperability among monitoring and modelling chains, uneven practices in uncertainty communication, and the complexity of compound and cascading events. The main conclusions indicate that the scientific and technological basis for multi-risk impact-based early warning is already available in many sectors, but that effective implementation in Europe will require progressive alignment of data standards, workflows, uncertainty representation, institutional coordination, and user-centred decision-support practices across weather and geo-hazard communities.