Extreme Climate Events in Morocco: Historical Analysis and Future Projections Based on CMIP6 Simulations

Abstract

Global warming has increased the frequency and severity of extreme climate events, a trend expected to persist throughout the 21st century unless effective mitigation measures are implemented. This study investigates historical (1980–2014) and future (2015–2100) changes in extreme climate events in Morocco. It utilises observed data and bias-corrected simulations from CMIP6 models under two scenarios: SSP2-4.5 and SSP5-8.5, based on 16 extreme climate indices. Bias correction effectively reduced model discrepancies, thereby improving the reliability of simulated indices. In the historical period, temperature-related indices indicate a strong intensification of warm extremes, including TXx (annual maximum of daily maximum temperature), TN90p (warm nights) and TX90p (warm days). At the same time, cold extremes such as CSDI (cold spell duration index), TN10p (cold nights) and TX10p (cold days) show a clear decline. Precipitation-related indices suggest a shift towards drier conditions, with reduced occurrences of heavy rainfall and longer dry spells (CDDs), particularly in the Atlantic (ATL) and Mediterranean (MED) regions. Future projections indicate continued warming, with more frequent and prolonged heatwaves. Total precipitation (PRCPTOT) is projected to decline, while short-duration, high-intensity rainfall events become more common, especially under the SSP5-8.5 scenario. Increase in global mean temperature directly increases the frequency, intensity and duration of temperature extreme events. In contrast, precipitation-related extremes exhibit more heterogeneous and scenario-dependent responses, reflecting the influence of complex and potentially non-linear processes. The southern Atlas and Saharan regions (SOA and SAH) emerge as climate hotspots, facing heightened risks of drought, heatwaves and flash floods. The projected decline in precipitation, combined with increasing rainfall irregularity, is likely to contribute to greater uncertainty and potential reductions in crop yields, thereby increasing the vulnerability of Moroccan agriculture. Overall, findings point to a transition towards a hotter, drier and more variable climate, with significant implications for water resource management and food security in Morocco.