This work explores the changing nature of major risks and the implications for systems that provide health services, transportation, energy, food and water, information and telecommunication and safety and security. There have been a host of large-scale disasters towards the end of the 20th and early 21st centuries: flooding in Europe, the emergence of virulent new diseases, terrorist attacks and major disruptions to critical infrastructures caused by computer viruses or technical failure. The forces shaping these changes are many and varied. Increasingly extreme weather conditions, population density, globalization and scientific innovation are confronting society with unknowable impacts and difficult choices. The book focuses on the increased vulnerability of major systems - any of which could be severely damaged by a single catastrophic event or a chain of events. It concentrates on three large risk clusters: natural disasters, technology-related risks and health-related risks and examines the underlying forces driving changes in these areas and identifies the challenges facing OECD countries in assessing, preparing for and responding to conventional and newly emerging hazards. It also offers a number of recommendations to governments and the private sector for improving the management of emerging systemic risks.