Intensification characteristics of hydroclimatic extremes in the Asian monsoon region under 1.5 and 2.0 °C of global warming

Abstract

Abstract. Understanding the influence of global warming on regional hydroclimatic extremes is challenging. To reduce the potential risk of extremes under future climate states, assessing the change in extreme climate events is important, especially in Asia, due to spatial variability of climate and its seasonal variability. Here, the changes in hydroclimatic extremes are assessed over the Asian monsoon region under global mean temperature warming targets of 1.5 and 2.0 ∘C above preindustrial levels based on representative concentration pathways (RCPs) 4.5 and 8.5. Analyses of the subregions classified using regional climate characteristics are performed based on the multimodel ensemble mean (MME) of five bias-corrected global climate models (GCMs). For runoff extremes, the hydrologic responses to 1.5 and 2.0 ∘C global warming targets are simulated based on the variable infiltration capacity (VIC) model. Changes in temperature extremes show increasing warm extremes and decreasing cold extremes in all climate zones with strong robustness under global warming conditions. However, the hottest extreme temperatures occur more frequently in low-latitude regions with tropical climates. Changes in mean annual precipitation and mean annual runoff and low-runoff extremes represent the large spatial variations with weak robustness based on intermodel agreements. Global warming is expected to consistently intensify maximum extreme precipitation events (usually exceeding a 10 % increase in intensity under 2.0 ∘C of warming) in all climate zones. The precipitation change patterns directly contribute to the spatial extent and magnitude of the high-runoff extremes. Regardless of regional climate characteristics and RCPs, this behavior is expected to be enhanced under the 2.0 ∘C (compared with the 1.5 ∘C) warming scenario and increase the likelihood of flood risk (up to 10 %). More importantly, an extra 0.5 ∘C of global warming under two RCPs will amplify the change in hydroclimatic extremes on temperature, precipitation, and runoff with strong robustness, especially in cold (and polar) climate zones. The results of this study clearly show the consistent changes in regional hydroclimatic extremes related to temperature and high precipitation and suggest that hydroclimatic sensitivities can differ based on regional climate characteristics and type of extreme variables under warmer conditions over Asia.

The Impacts of Global Warming on Climate Zone Changes Over Asia Based on CMIP6 Projections

“…We determine the reference period corresponding to a global mean temperature increase in the reference period and future periods corresponding to increases from 1.5°C to 5.0°C above the temperature during the PI period (1861–1890) under the two SSP scenarios (e.g., SSP1‐2.6 and SSP5‐8.5) using the time sampling method (James et al., 2017; Kim & Bae, 2020; Sylla et al., 2018). In this process, the individual 30‐year periods and their central years (i.e., the median year of each period) are determined based on the temperature anomalies relative to the PI period temperature.…”

“…This method adjusts the whole distribution of two data sets by matching the cumulative distribution function (CDF) of the climate model data to the CDF of the observed data on a daily basis, thereby improving the mean, variance, and extreme values. The method is an effective and simple way to correct the systemic biases in climate simulations; therefore, it is widely used for climate models (Kim & Bae, 2020; MacDonald et al., 2018).…”

“…of the climate model data to the CDF of the observed data on a daily basis, thereby improving the mean, variance, and extreme values. The method is an effective and simple way to correct the systemic biases in climate simulations; therefore, it is widely used for climate models (MacDonald et al, 2018;Kim et al, 2020a).…”

“…Many studies have suggested that extreme climate responses to enhanced emission forcings are relatively clear and straightforward (e.g., Harrington & Otto, 2018; King & Karoly, 2017; Li et al., 2018). On the other hand, long‐term mean climates are much more obscure at the regional scale (Kim & Bae, 2020) because climatology is influenced by local radiative forcings, as well as global circulation effects, such as the advection of air masses from other regions (Paeth et al., 2015). In addition, for each region, climate plays an important role as the primary natural constraint regulating natural and human systems, such as vegetation growth (Nemani et al., 2003), food security (King et al., 2018), water availability, and water‐related disasters (Son & Bae, 2015).…”

“…For analyses of the latest CMIP6 outputs based on the ESM, it is possible to suggest updated results and a better understanding of climate shifts over the Asian monsoon region. In this study, we assess the global warming impacts on the regional climate features corresponding to warming targets with a focus on the Asian monsoon region (see Figure 2), as delineated by Kim and Bae (2020). The climate classification method is applied to investigate the regional climate features (e.g., types and spatial boundary) and examine the changes in climate features responding to potential global warming conditions based on multiple ensembles of ESM climate projections.…”