This book is about early warning in the context of civil protection. The concept of civil protection refers to the protection of people, the environment and property in the event of man-made, technological and natural risks or emergencies. Early warning is an essential element of any functioning civil protection system. The study defends a wide understanding of the concept, consisting of five 'phases' of an 'early warning system'. Early warning starts with risk assessment, followed by prevention, which in a way should prove that the early warning system works. The third phase is that of monitoring the risks in order to detect possible signals with respect to a potential forthcoming or occurring emergency. The fourth phase is the dissemination of warnings. Finally, early warning includes also response, in the sense that response can be more or less timely. The main puzzle discussed in this study is that when does early warning work in relation to civil protection and, more significantly perhaps, when does it fail, and for what reasons. While providing a general framework for analyzing these questions, the book also includes some detailed case studies in fields such as climate change related floods and spatial planning, sudden sea water rise, electricity blackouts, and maritime safety in cross-border context.