Country: World Source: UN Office for Disaster Risk Reduction Please refer to the attached file. This publication aims to serve as a comprehensive, practical reference on probabilistic risk assessments (PRA) and how they strengthen impact-based forecasting (IBF) and anticipatory action (AA), in support of the Early Warnings for All initiative. It explains the scientific foundations, data requirements, and methodological steps needed to generate probabilistic risk information that accounts for uncertainty and supports decision-making. By linking PRA, IBF, and AA, it seeks to build regional and national capacities in the Caribbean to anticipate disaster impacts, prioritize interventions, and reduce losses before disasters strike. The document underscores the limitations of historical loss data, which are typically incomplete, inconsistent, or too short to capture catastrophic events, and highlights the role of DELTA Resilience, UNDRR’s next generation system for tracking hazardous events, losses, and damages to address this gap. A strong conceptual and methodological link exists between IBF and probabilistic risk assessments (PRA). PRA provides a rigorous framework for representing uncertainties in hazard, exposure, and vulnerability, and for generating long term risk metrics such as loss exceedance curves (LECs). These metrics are essential not only for risk informed decision making but also for designing anticipatory action (AA) mechanisms, which should rely on forecast based triggers and require robust estimates of triggering frequency to ensure their financial sustainability. Executive Summary Early warning systems (EWS) are among the most cost effective measures for reducing disaster risk and, in many cases, for adapting to climate change, with evidence showing that even a 24 hour warning can reduce damages by up to 30%. Their effectiveness, however, depends on the integration of hazard monitoring, forecasting, communication, preparedness, and strong governance, an approach fully aligned with the Sendai Framework for Disaster Risk Reduction 2015-2030. To accelerate global EWS coverage, the United Nations Secretary-General launched the Early Warnings for All (EW4All) initiative in 2022. Co led by WMO and UNDRR, it aims to ensure that every person on Earth is protected by robust early warning systems by 2027. UNDRR leads Pillar 1: Disaster Risk Knowledge, supporting countries in developing and curating hazard, exposure, vulnerability, and loss data; strengthening risk governance; and ensuring that risk information is accessible, interoperable, and actionable across decision making processes. Across the Americas and the Caribbean, national EW4All roadmaps highlight the need to advance impact based forecasting (IBF), meaning a shift from forecasting “what the hazard will be” to “what the hazard will do. ” IBF requires robust exposure and vulnerability models capable of translating forecasted hazard intensities into expected impacts on people, infrastructure, and livelihoods. While IBF has advanced for hydrometeorological hazards, its application to volcanic eruptions, tsunamis, and other hazards remains limited, though necessary. The document underscores the limitations of historical loss data, which are typically incomplete, inconsistent, or too short to capture catastrophic events, and highlights the role of DELTA Resilience, UNDRR’s next generation system for tracking hazardous events, losses, and damages to address this gap. A strong conceptual and methodological link exists between IBF and probabilistic risk assessments (PRA). PRA provides a rigorous framework for representing uncertainties in hazard, exposure, and vulnerability, and for generating long term risk metrics such as loss exceedance curves (LECs). These metrics are essential not only for risk informed decision making but also for designing anticipatory action (AA) mechanisms, which should rely on forecast based triggers and require robust estimates of triggering frequency to ensure their financial sustainability
World: Probabilistic risk assessments to improve impact-based forecasts and strengthen anticipatory action in Latin America and the Caribbean
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