Future projection of seasonal drought characteristics using CMIP6 in the Lancang-Mekong River Basin

As the most widespread natural hazard, drought has significant impacts on the livelihood and ecosystems in the Lancang-Mekong River Basin (LMRB). However, few studies focus on the seasonal characteristics of drought in the LMRB, especially under future climate projections by the Sixth Phase of Coupled Model Inter-comparison Project (CMIP6). This study filled the knowledge gap using SPI and SPEI, based on eight GCMs of CMIP6 under three scenarios (i.e., SSP1-2.6, SSP2-4.5, SSP5-8.5). Our results show that the LMRB tends to experience wetter wet season and drier dry season with the rising temperature considered (based on SPEI), while the temporal trend of dry-season SPI is not significant. The future trends of SPEI are -0.006 per year and -0.011 per year under SSP2-4.5 and SSP5-8.5, respectively. The trend magnitudes demonstrate spatial heterogeneities. Our evaluation based on SPEI shows that the most notable increases of dry-season drought (in terms of duration and intensity) are distributed in the middle reaches of LMRB. The upper Lancang and middle Mekong basin will likely experience more wet-season droughts. The dry-season drought accounts for 60% of total drought events in the near future (i.e., 2021-2055) and more than 80% in the far future (i.e., 2061-2095) under SSP2-4.5. Effective strategies are needed to enhance food and drinking water security in the LMRB, especially for the dry seasons under a changing climate.

Automated summary

This study fills the research gap on the seasonal characteristics of drought in the Lancang-Mekong River Basin (LMRB). The results reveal that the LMRB will experience wetter wet seasons and drier dry seasons with rising temperatures. The future trends of drought show spatial heterogeneities. The study emphasizes the need for effective strategies to enhance food and drinking water security, especially during the dry seasons.