Early warning technologies have greatly benefited from recent advances in communication and information technologies and an improved knowledge on natural hazards and the underlying science. Nevertheless many gaps still exist in early warning technologies and capacities — especially in the developing world — and yet a lot has to be done for the development of a global scale multi-hazard system. This in-depth bulletin introduces the basic concepts of early warning systems, the role of earth observation for disasters and environment and it focuses on the existing early warning/monitoring systems while addressing the need to fill in the operational gaps for slow-onset hazards both in monitoring, communication and response phases to facilitate timely decision-making.
