Drought Characteristics and Risks in Iran: A Four‐Dimensional Copula‐Based Approach Under Future Climate Scenario

ABSTRACT This study investigates the dynamics of drought characteristics in Iran under historical (1966–2019) and future (2020–2050) conditions using the SSP2‐4.5 scenario. Four drought characteristics—severity, duration, magnitude, and peak intensity—were analysed through the Standardised Precipitation Index (SPI) and copula‐based multivariate models. Data from 39 synoptic stations were utilised, with projections downscaled from the HadGEM3‐GC31‐LL model using LARS‐WG. The results show a general reduction in drought severity, duration, and magnitude under the SSP2‐4.5 scenario. The copula‐based analysis demonstrated that the T‐copula was the optimal fit for 96% of stations in the future period, compared to 54% in the historical period. This underscores its ability to capture the dependencies among drought characteristics, particularly under changing climatic conditions. Conditional probabilities and risks for 20‐year return periods showed an increase under SSP2‐4.5, indicating a higher likelihood of less severe but more frequent drought events within shorter timeframes. Conversely, for 50‐year return periods, severe droughts remain rare but show a moderate increase in probability and risk compared to the historical period. These findings emphasise the need for region‐specific adaptation strategies to address increasing drought risks and disparities under future climate scenarios.