A typology of compound weather and climate events

Abstract

<p>Weather- and climate-related extreme events such as droughts, heatwaves and storms arise from interactions between complex sets of physical processes across multiple spatial and temporal scales, often overwhelming the capacity of natural and/or human systems to cope. In many cases, the greatest impacts arise through the ‘compounding’ effect of weather and climate-related drivers and/or hazards, where the scale of the impacts can be much greater than if any of the drivers or hazards occur in isolation; for instance, when a heavy precipitation falls on an already saturated soil causing a devastating flood. Compounding in this context refers to the amplification of an impact due to the occurrence of multiple drivers and/or hazards either because multiple hazards occur at the same time, previous climate conditions or weather events have increased a system’s vulnerability to a successive event, or spatially concurrent hazards lead to a regionally or globally integrated impact. More generally, compound weather and climate events refer to a combination of multiple climate drivers and/or hazards that contributes to societal or environmental risk.</p><p>Although many climate-related disasters are caused by compound events, our ability to understand, analyse and project these events and interactions between their drivers is still in its infancy. Here we review the current state of knowledge on compound events and propose a typology to synthesize the available literature and guide future research. We organize the highly diverse event types broadly along four main themes, namely preconditioned, multivariate, temporally compounding, and spatially compounding events. We highlight promising analytical approaches tailored to the different event types, which will aid future research and pave the way to a coherent framework for compound event analysis. We further illustrate how human-induced climate change affects different aspects of compound events, such as their frequency and intensity through variations in the mean, variability, and the dependence between their climatic drivers. Finally, we discuss the emergence of new types of events that may become highly relevant in a warmer climate.</p>

Brief communication: The role of using precipitation or river discharge data when assessing global coastal compound flooding

“…The two approaches investigated here provide information only on the potential for CF. The actual CF occurrence depends also on the local topography which can favour or not the interaction between the CF drivers; also, concurrent but not hydrologically-interacting storm surge and pluvial or fluvial flooding are relevant as they can, e.g., limit the ability to respond to emergency, and amplify the impacts that the two hazards would have caused if they occurred in isolation (Martius et al, 2016;Barton et al, 2016;Zscheischler et al, 2019). Moreover, while the two approaches investigated here are supposed to represent different CF mechanisms, separating the CF mechanisms in this way could be misleading, as CF may happen due to a combination of river discharge, local rainfall and associated surface runoff, together with high sea level.…”

Nonstationary weather and water extremes: a review of methods for their detection, attribution, and management

“…Interest in compound hydrological extremes is growing rapidly, not least because these events can deliver particularly severe societal impacts (de Ruiter et al, 2019;Raymond et al, 2020a;Zscheischler et al, 2020). Although rarity and complexity pose challenges for their assessment, physical reasoning and empirical methods have highlighted that they can be sensitive to anthropogenic climate warming (AghaKouchak et al, 2020) as well as modes of climate variability (Hillier et al, 2020).…”

Eliciting lessons from Small- and Medium-Sized Enterprises (SMEs) for natural disaster resilience planning and recovery during the COVID-19 pandemic:

“…Compound risks materialize in concurrent or successive extreme events. Compound weather and climate risks describe combinations of multiple climate drivers and/or hazards that contribute to societal and/or environmental risk (Zscheischler et al, 2020) and tend to have a multiplier effect on the risk posed to society, infrastructure, and the environment. Concurrent events occur simultaneously, i.e., on the same day and in the same region (Leonard et al, 2014;Liu and Huang, 2015).…”