Title: UnDerstanding And Modeling cOmpound CLimate and weather EventSAcronym: DAMOCLES SummaryHazards such as floods, wildfires, heatwaves and droughts usually result from a combination of interacting physical processes that occur across multiple spatial and temporal scales. The combination of physical processes leading to an impact is referred to as a Compound Event. Examples of high-impact Compound Events include (i) droughts, heatwaves, wildfire and/or air pollution and their interactions involving a complex interplay between temperature, humidity and precipitation (ii) extreme precipitation, river discharge and storm surge interactions, combining coastal storm processes with fluvial/pluvial and ocean dynamics (iii) storms including clustering of major events leading to spatial and/or temporal dependence.Climate change alters many of these processes and their interaction, making projections of future hazards based on single driver analyses difficult. Impact studies considering only one driver usually fail to assess the extent of the impacts of Compound Events. It is thus not clear whether climate models can capture major changes in risk associated with Compound Events. Existing modelling approaches used to assess risk may therefore lead to serious mal-adaptation.DAMOCLES will (a) identify key process and variable combinations underpinning Compound Events (b) describe the available statistical methods for modelling dependence in time, space, and between multiple variables (c) identify data requirements needed to document, understand, and simulate Compound Events, and (d) propose an analysis framework to improve the assessment of Compound Events. DAMOCLES brings together climate scientists, impact modellers, statisticians, and stakeholders to better understand, describe and project Compound Events, and foresees a major breakthrough in future risk assessments.