L13. Compound extremes: understanding process interactions in hydrology and climate science

Climate and weather related events such as flooding, wildfires and cyclones pose significant risks to society. The overall impact of these events is determined by the interaction of many processes acting together, where the manner in which the processes are combined is often just as important as the state (extreme or otherwise) of each of the driving variables. In this sense, almost all extreme events of importance to society are governed by many interacting variables acting at multiple spatial and temporal scales. The IPCC recently has referred to such situations as ‘compound extremes’, defined as: (1) two or more extreme events occurring simultaneously or successively, (2) combinations of extreme events with underlying conditions that amplify the impact of the events, or (3) combinations of events that are not themselves extremes but lead to an extreme event or impact when combined. This session aims to address climate extremes which are caused by multiple processes. Papers are sought which address the following themes: (1) Climate extremes (floods, fires, drought, water quality events, etc) involving multiple interacting meteorological forcings (2) Climate model evaluation studies which describe the capability of models to represent dependence between variables in space and time (3) Statistical techniques for representing joint dependence in meteorological variables in space and time (4) Measures for quantifying risk of extreme impacts.