Collapse of climatic refugia under compound climate hazards in the Middle East and North Africa

The Middle East and North Africa (MENA) is a hotspot of climate risk, yet how interacting extremes reorganize into persistent multi-hazard regimes remains poorly constrained. We introduce a compound-hazard framework that diagnoses and projects compound climate states (CCS): enduring configurations in which multiple hazard dimensions are jointly elevated within a common analysis period, implying heightened impact potential beyond single hazards. We develop three interpretable indices: the Compound Heat-Dryness Index (CHDI), Compound Heat-Wetness Duration Index (CHWDI), and Compound Thermal Variability Index (CTVI). These indices are period-scale hazard-state diagnostics rather than direct measures of event-scale simultaneity. To reduce uncertainty from coarse and biased climate-model output, we refine CMIP6 simulations and SSP-based projections using a stacking-ensemble architecture with a GW-XGBoost meta-learner benchmarked against ERA5. Refined projections indicate erosion of historical climatic refugia across the temperate northern belt and transitional seasons. Under SSP5–8.5, hot-dry states approach near-perennial dominance, humid-heat hazards intensify along coastal corridors, and climate whiplash strengthens across water towers, increasing hydro-geomorphic and infrastructure risks. Mitigation moderates these shifts, preserving seasonal variability and limiting the spread of hazard states. These diagnostics support monitoring of compound climate-state transitions and inform UNFCCC-aligned adaptation and loss-and-damage preparedness, while supporting IPCC assessments of systemic risk.