Changing climate conditions are supposed to have particularly strong impacts on agricultural production in the tropics with strong implications on food security. Ethiopia’s economy is profoundly dominated by agriculture, contributing to around 40% of the gross domestic product. Thereby, Ethiopia is one of the most vulnerable countries to the impact of climate change and has a wide gap in regional climate change impact studies. In this study, we systematically investigate climate change impacts on yields for the Gambella region in Ethiopia, exemplarily for maize. Here, we show how yields change until 2100 for RCPs 2.6, 4.5, and 8.5 from a climate model ensemble under rainfed and irrigated conditions. While rainfed yields decrease by 15% and 14% respectively for RCPs 2.6 and 4.5, yields decrease by up to 32% under RCP 8.5. Except for RCP 8.5, yields are not further decreasing after 2040–2069. We found that temperature increase, changing soil water availability, and atmospheric CO₂ concentration have different effects on the simulated yield potential. Our results demonstrate the dominance of heat response under future climate conditions in the tropical Gambella region, contributing to 85% of total yield changes. Accordingly, irrigation will lose effectiveness for increasing yield when temperature becomes the limiting factor. CO₂, on the other hand, contributes positively to yield changes by 8.9% for RCP 8.5. For all scenarios, the growing period is shorted due to increasing temperature by up to 29 days for RCP 8.5. Our results suggest that new varieties with higher growing degree days are primarily required to the region for adapting to future climate conditions.

人们认为，气候条件的变化将对热带地区的农业生产产生特别强烈的影响，并对粮食安全产生重大影响。埃塞俄比亚的经济以农业为主导，约占国内生产总值的40％。因此，埃塞俄比亚是最容易受到气候变化影响的国家之一，在区域气候变化影响研究中存在很大差距。在这项研究中，我们系统地研究了气候变化对埃塞俄比亚甘贝拉地区（例如玉米）单产的影响。在这里，我们展示了在雨养和灌溉条件下，气候模型集合的RCP 2.6、4.5和8.5的产量在2100年之前如何变化。尽管RCP 2.6和4.5的雨养单产分别降低了15％和14％，但在RCP 8.5下，单产下降了高达32％。除了RCP 8.5，2040年至2069年之后，单产不会进一步下降。我们发现温度升高，土壤水供应量变化和大气中的CO₂浓度对模拟的产量潜力有不同的影响。我们的结果证明了热带Gambella地区在未来气候条件下热响应的优势，占总产量变化的85％。因此，当温度成为限制因素时，灌溉将失去提高产量的有效性。另一方面，对于RCP 8.5，CO ₂对产量变化有8.9％的正贡献。在所有情况下，由于RCP 8.5的温度增加了多达29天，因此生长期缩短了。我们的结果表明，该地区主要需要具有较高生长天数的新品种，以适应未来的气候条件。