Probabilistic risk assessments to improve impact-based forecasts and strengthen anticipatory action in Latin America and the Caribbean

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.