Probabilistic analysis of future drought propagation, persistence, and spatial concurrence in monsoon-dominant Asian regions under climate change

Abstract. This study examines future drought propagation (the temporal transition from meteorological to agricultural droughts), persistence (inter-seasonal agricultural droughts), and spatial concurrence (simultaneous occurrence of monsoonal agricultural droughts across regions) under climate change using a multivariate copula approach in monsoon-dominant Asia. The standardised precipitation index (SPI) and standardised soil moisture index (SSI) are used to analyse meteorological and agricultural droughts, respectively. Under the worst-case emission scenario (Shared Socioeconomic Pathway, SSP5-8.5), South Asia (excluding western and peninsular India) and eastern China are projected to experience intensified drought propagation compared to in the historical period (1975–2014). In addition to increased propagation in these regions, the propagated agricultural droughts are expected to persist across seasons in the future. On the hydrologically significant Tibetan Plateau, all-season droughts that were historically rare, with return periods exceeding 50 years, could occur as frequently as once every 5 years in the far-future period (2061–2100). Random forest models indicate that the temperature is a key driver of future agricultural droughts in nearly half of the study area. The increasing non-rainfall-related agricultural droughts in the far future could be attributed to the rise in temperature. Based on bivariate return periods of spatial concurrence, frequent future spatial drought concurrence is anticipated between populous South Asia and East Asia compared to the historical time frame, posing risks to water and food security. Conversely, Southeast Asia is projected to experience reduced spatial drought concurrence with other regions, which could encourage greater regional cooperation. Overall, this comprehensive approach, which integrates three aspects of drought dynamics, offers valuable insights for climate change mitigation, planning, and adaptation.