The slightest change in rainfall could have a significant impact on rain-fed agriculture in countries like Ghana. This study evaluated for the first time the performance of the statistical downscaling model (SDSM-DC) at 2m spatial resolution in simulating rainfall in Ghana for the base period 1981–2010. It further analysed the projected changes in seasonal rainfall pattern across different agro-ecological zones for the twenty-first century under RCP 4.5 and 8.5 emission scenarios over Ghana. Ensemble mean of simulated rainfall data (2011–2099) generated by 43 GCMs in the Coupled Model Intercomparison Project Phase 5 (CMIP5) were used as base factors for local future climate scenarios generation. Performance analysis of SDSM-DC shows a Nash–Sutcliffe efficiency, percent bias and RMSE observations standard deviation ratio of 0.88, −19 and 0.34, respectively. Generally, seasonal rainfall amount is expected to increase between 10 and 40% in all the agro-ecological zones in Ghana by the end of the twenty-first century. Off-season rainfall in December–February shows more than 100% increase in the Guinea Savannah zone. Rainfall projected under RCP 4.5 was on average 2% higher than RCP 8.5 in all the seasons throughout the century. Based on these results, it is appropriate to suggest a high incidence of flooding across Ghana in the twenty-first century. This could have dire consequences on agriculture which contribute to a large proportion of Ghana’s GDP. Therefore, for sustainable food production and security in the twenty-first century, Ghana needs climate adaptation policies and programmes that encourage the design and implementation of early warning systems of meteorological hazards and the introduction of new crop varieties that are flood tolerant.

中文翻译：

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21 世纪加纳季节性降雨量增加及其对农业生产力的潜在影响

降雨量的最细微变化都可能对加纳等国家的雨养农业产生重大影响。本研究首次评估了空间分辨率为 2m 的统计降尺度模型 (SDSM-DC) 在模拟加纳 1981-2010 年基期降雨中的性能。它进一步分析了 21 世纪在 RCP 4.5 和 8.5 排放情景下加纳不同农业生态区的季节性降雨模式的预测变化。耦合模型比对项目第 5 阶段 (CMIP5) 中 43 个 GCM 生成的模拟降雨数据 (2011-2099) 的集合平均值被用作当地未来气候情景生成的基础因素。SDSM-DC 的性能分析显示 Nash-Sutcliffe 效率、偏差百分比和 RMSE 观测标准偏差比为 0.88、-19 和 0.34，分别。一般而言，到 21 世纪末，加纳所有农业生态区的季节性降雨量预计将增加 10% 至 40%。12 月至 2 月的淡季降雨表明几内亚萨凡纳地区增加了 100% 以上。在整个世纪的所有季节中，根据 RCP 4.5 预测的降雨量平均比 RCP 8.5 高 2%。根据这些结果，可以认为 21 世纪加纳洪水发生率很高。这可能会对占加纳 GDP 很大一部分的农业产生可怕的影响。因此，为了二十一世纪的可持续粮食生产和安全，