Towards advancing scientific knowledge of climate change impacts on short-duration rainfall extremes

Abstract

A large number of recent studies have aimed at understanding short-duration rainfall extremes, due to their impacts on flash floods, landslides and debris flows and potential for these to worsen with global warming. This has been led in a concerted international effort by the INTENSE Crosscutting Project of the GEWEX (Global Energy and Water Exchanges) Hydroclimatology Panel. Here, we summarize the main findings so far and suggest future directions for research, including: the benefits of convection-permitting climate modelling; towards understanding mechanisms of change; the usefulness of temperature-scaling relations; towards detecting and attributing extreme rainfall change; and the need for international coordination and collaboration. Evidence suggests that the intensity of long-duration (1 day+) heavy precipitation increases with climate warming close to the Clausius–Clapeyron (CC) rate (6–7% K −1 ), although large-scale circulation changes affect this response regionally. However, rare events can scale at higher rates, and localized heavy short-duration (hourly and sub-hourly) intensities can respond more strongly (e.g. 2 × CC instead of CC). Day-to-day scaling of short-duration intensities supports a higher scaling, with mechanisms proposed for this related to local-scale dynamics of convective storms, but its relevance to climate change is not clear. Uncertainty in changes to precipitation extremes remains and is influenced by many factors, including large-scale circulation, convective storm dynamics andstratification. Despite this, recent research has increased confidence in both the detectability and understanding of changes in various aspects of intense short-duration rainfall. To make further progress, the international coordination of datasets, model experiments and evaluations will be required, with consistent and standardized comparison methods and metrics, and recommendations are made for these frameworks. This article is part of a discussion meeting issue ‘Intensification of short-duration rainfall extremes and implications for flash flood risks’.

Interannual Variability and Trends of Extreme Rainfall Indices over Benin

“…An extreme rainfall event is an occurrence that is significantly different from typical rainfall at a specific area and time of year. In the context of climate change, extreme rainfall events are becoming more frequent and intense [1]. It is evidence that global warming has altered the water cycle, which has led to change in the magnitude, frequency and probability of extreme rainfall around the world [2][3][4].…”

Estimating design hydrologic extremes in a warming climate: alternatives, uncertainties and the way forward

“…The design flood will depend on the extent of change the three factors (rainfall depth, temporal pattern and AMC) exhibit. While a 6–7% increase in the design depth with each degree rise in temperature follows from the Clausius–Clapeyron relationship, increases above this have been observed for sub-daily rainfall (see [12]). There are also locations where the observed day-to-day variability of rainfall intensity to temperature is, in fact, negative [13,14], though the negative scaling appears to be an aberration (see [15]) forced by the unusual relationship temperature change exhibits with the occurrence of rainfall in tropical climates [16,17].…”

Convection‐permitting modeling with regional climate models: Latest developments and next steps

“…Other important benefits in the use of CPRCMs to bridge the gap between GCMs and end‐users (Maraun et al, 2010) come from their capacity to simulate sub‐daily and shorter duration precipitation, including extremes (Barbero et al, 2019; Fowler et al, 2021a,b,c; Gutjahr et al, 2016; Tölle et al, 2018; Vergara‐Temprado et al, 2021; Westra et al, 2014). CPRCMs are capable of more realistically simulating fine‐scale meteorological phenomena that produce large amounts of rainfall, such as MCS (Feng et al, 2018; Prein et al, 2021; Prein, Liu, et al, 2020; Prein, Liu, Ikeda, et al, 2017), stronger tropical cyclones with lower central minimum pressure (Gutmann et al, 2018; Kanada et al, 2013), orographic precipitation (Jing et al, 2018; Prein, Holland, et al, 2013; Reder et al, 2020), drylines (Scaff et al, 2021), and squall lines (Purr et al, 2019).…”

“…The improved physical realism of CPRCMs has proven to affect the sub‐daily extremes with a general intensification of hourly peak intensity (Ban et al, 2015; Fosser, Kendon, Stephenson, & Tucker, 2020; Fowler et al, 2021a,b,c; Hodnebrog et al, 2019; Huang, Swain, & Hall, 2020; Kendon et al, 2014, 2019; Knist et al, 2020a; Lenderink et al, 2019; Prein, Rasmussen, Ikeda, et al, 2017; Vergara‐Temprado et al, 2021). At mid‐latitudes, the improvement is most apparent in summertime extremes, where convection is playing a large role for the most intense events (Fosser, Kendon, Stephenson, & Tucker, 2020; Kendon et al, 2014).…”