Climate Extremes and Society: Definition, diagnosis, and origin of extreme weather and climate events

Extreme weather and climate events are a major source of risk for all human societies. There is a pressing need for more research on such events. Various societal changes, such as increased populations in coastal and urban areas and increasingly complex infrastructure, have made us potentially more vulnerable to such events than we were in the past. In addition, the properties of extreme weather and climate events are likely to change in the twenty-first century owing to anthropogenic climate change. The definition, classification, and diagnosis of extreme events are far from simple. There is no universal unique definition of what is an extreme event. This chapter discusses these issues and presents a simple framework for understanding extreme events that will help enable future work in this important area of climate science and global reinsurance.