Abstract
Forecasting and early warning systems are important investments to protect lives, properties and livelihood. The Sendai Framework for Disaster Risk Reduction, agreed upon at the Third UN World Conference on Disaster Risk Reduction in 2015, calls for a substantial increase in the availability of multi-hazard early warning systems and rapid disaster risk information by 2030. While early warning systems are frequently used to predict the magnitude, location and timing of potentially damaging events, these systems rarely provide impact estimates, such as the expected amount and distribution of physical damage, human consequences, disruption of services or financial loss. Complementing early warning systems with impact forecasts has a two-fold advantage: it would provide decision makers with richer information to take informed decisions about emergency measures, and focus the attention of different disciplines on a common target. This would allow capitalizing on synergies between different disciplines and boosting the development of multi-hazard early warning systems. This review discusses the state-of-the-art in impact forecasting for a wide range of natural hazards. We outline the added value of impact-based warnings compared to hazard forecasting for the emergency phase, indicate challenges and pitfalls, and synthesize the review results across hazard types most relevant for Europe.