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Abstract:
Context
Madagascar is one of the most food-insecure countries globally, with 40% of the population undernourished and 90% unable to afford a healthy diet. Smallholder farmers rely primarily on low-yielding, rainfed subsistence farming and are highly vulnerable to climate change due to their dependence on seasonal rainfall and limited adaptive capacity.
Objective
The objective of this study was to quantify climate change impacts on maize and peanut yields across Madagascar and to evaluate the effectiveness of low-cost adaptation strategies informed by household survey data.
Methods
Crop simulations were conducted with the Agricultural Production Systems Simulator (APSIM) for a historical baseline and future periods up to 2100 under three socio-economic pathways (SSP1–2.6, SSP3–7.0, SSP5–8.5). High-resolution climate projections (CMIP6/ISIMIP3b), diverse spatial datasets and household survey data from 624 farmers informed the modelling framework and guided the selection of adaptation strategies. For maize, the adaptation potential of different sowing dates and crop cultivars was tested; for peanut, the CO2 fertilization effect was isolated by comparing increasing versus constant atmospheric [CO2].
Results and Conclusion
Madagascar is projected to undergo substantial warming during the main cropping season, accompanied by shifts in rainfall patterns. Maize yields are likely to decline by −8% to −52%, with losses intensifying under higher emissions and later periods. In contrast, peanut yields are projected to increase by +5% to +10%, primarily due to the CO2 fertilization effect; without it, yields would decline, highlighting the severity of future climatic stress. Moreover, yield variability is projected to increase for maize but remain stable for peanut. Among adaptation strategies, short-cycle cultivars sown late performed best for maize under future climates, yet no tested combination could reverse negative yield impacts. Our findings underscore the distinct responses of C4 and C3 crops to climate change and the growing risks for food security, given farmers' limited coping mechanisms.
Significance
This study provides the first national-scale assessment of climate change impacts on maize and peanut in Madagascar. It demonstrates the added value of combining household survey data with process-based crop models and emphasizes that that a broader portfolio of accessible and effective adaptation measures is needed to sustain smallholder livelihoods under climate change.
