Explaining Climatic Drivers of Yield Anomalies in Global Crop Models Through Metamodel‐Based Attribution

Global gridded crop models (GGCMs) are important tools for assessing climate impacts on agriculture, yet significant divergence in their projections limits interpretability, and impact studies often treat GGCMs as black boxes. Targeted ensemble sensitivity analyses are demanding and not transferable to different ensembles. Here, we comprehensively evaluate climatic and soil drivers of crop yield anomalies in a state-of-the-art GGCM ensemble, using maize as a representative crop. Gradient boosting classifiers detect anomalies, SHapley Additive exPlanations (SHAP) values quantify feature importance, and methods are applied to a recent GGCM experiment driven by reanalysis climate data. We find broadly similar climatic drivers across the ensemble, though feature importance distributions differ. Low precipitation dominates under rainfed conditions, while solar radiation typically ranks second, highlighting that drought impacts depend on atmospheric water demand often omitted from sensitivity analyses. In some GGCMs, excess rather than insufficient water drives anomalies. The comparison with climate sensitivities derived from a global yield reference data set indicates that no single GGCM performs best across all climate regions. ... mehrIndividual GGCMs may respond well to one climatic stressor but not others, underscoring that bulk benchmarking of GGCMs against observations can obfuscate processes requiring targeted improvement. Our findings demonstrate that evaluating opportunistic data, that is, experiments produced for other purposes, yields vital insights into GGCM divergence in impact studies. Code is publicly available on GitHub to support future attribution analyses and inform broad audiences about drivers of observed results.