Increased Risk of Extreme Precipitation over an Urban Agglomeration with Future Global Warming

Abstract

Recent decades have witnessed an increased occurrence of natural disasters, including floods associated with extreme precipitation (EP) in cities (IPCC AR6, 2022). Making cities safe, resilient, and sustainable is one of United Nations Sustainable Development Goals 2030 (SDG2030, especially Goal 11; United Nations, 2015). Achieving this goal is a challenge because cities are exposed to changing large-scale climatic feedbacks, and cities themselves are creating their microclimate. Such multiscale climatic forcing is causing non-stationarity in the climate system, which results in an increasing trend of unprecedented extreme weather and climate events that might occur in the future (Diffenbaugh et al., 2017;Fischer et al., 2021). As a result, urban areas that are designed based on historical hydroclimate conditions continue to be exposed to higher risk due to climate impacts, especially urban floods (Mishra et al., 2022;Ye & Niyogi, 2022). Indeed, it is recognized that for some regions, precipitation extremes will become more frequent, more widespread, and/or more intense during the 21st century, and cities will be disproportionately at higher risk (Meyer et al., 2020).A basis of framing the precipitation change due to climate warming is through the classical Clausius-Clapeyron (CC) relation (Fowler, Lenderink, et al., 2021;Lenderink & van Meijgaard, 2009). The CC equation defines the saturation specific humidity of the atmosphere as a function of temperature. Hence, specific humidity near the Earth's surface is anticipated to rise at a rate of approximately 7% per degree warming (K −1 ). Several past studies have shown that both short-(<1 day) and long-duration (>1 day) precipitation extremes intensify at a rate consistent with the increase in atmospheric moisture (∼7% K −1 ; Allan & Soden, 2008). In some regions,