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Sub-Saharan Africa is projected to be exposed to substantial climate change hazards, especially in its agricultural sector, so adaptation will be necessary to safeguard crop yields. Tropical and subtropical maize production regions approach critical temperature thresholds in the growing season already in today's climate, and climate change might already be contributing to this. In this study we analyse the impact of anthropogenic climate change on maize yields and the potential for adaptation in Cameroon. We innovate by introducing a counterfactual climate as baseline to a definition for adaptation potential proposed in the literature to assess the relative benefit heat-tolerant crop varieties have already under current and under projected climate change. Spatially detailed simulations of maize yields are performed using the process-based crop model APSIM with W5E5 reanalysis data and bias-corrected and downscaled climate model data from CMIP6/ISIMIP3b for counterfactual, historical and projected future climate scenarios SSP1-2.6 and SSP3-7.0. It is found that unadapted maize yields experience significant losses under all climate change scenarios, with mean losses of 0.3 t ha−1 for the current period compared to the counterfactual climate without anthropogenic climate forcings and that yields are significantly higher for the heat-tolerant varieties across all scenarios simulated. Yield impacts of heat tolerance are highest under projected climate change, making it effective climate change adaptation. This result is robust to the exact value of parameterised heat tolerance. Breeding heat-tolerant varieties as parameterised in this study can be an effective adaptation but is still not enough to mitigate simulated losses under a high-emissions scenario.
