• Energy Research

Concern over future food security in southern Africa has led to various studies that assess the impact of climate change on crops in the region. The results vary according to applied methods and tools. This study reviewed and consolidated results from 19 recent studies which quantitatively project the impact of climate change on crops for the 21st century in southern Africa. Results were assessed according to crop modelling techniques, which included process-based, statistical and economic (Ricardian) modelling. Studies were assessed for their reporting and recommendations concerning adaptation and CO2 fertilisation. Results suggest that the aggregate impact of climate change on crops in southern Africa will be negative. Maize yields are projected to decline on average by 18%. The collective impact of climate change on all crop yields shows a median decline of − 11% and − 14% respectively under process-based and statistical methodologies. Median impacts show declining crop yields through the 21st century. No significant change in the near future, − 18% for the mid century and − 30% for late century. GCM driven Ricardian projections are highly variable. However, uniform climate scenarios project a median revenue decline. Notwithstanding the challenges of such a review; lack of data, bias towards reported methods and tools, uncertainty, scale etc., results indicate that climate change may impact southern African crops in important ways thereby making adaptation essential. Adaptation and CO2 fertilisation could potentially moderate the negative impacts of climate change. This implies a need for studies into future adaptation that consider CO2 fertilisation.

Large uncertainties about the impacts of climate change and adaptation options on the livestock component of heterogeneous African farming systems hamper tailored decision making towards climate-smart agriculture. This study addressed this knowledge gap through the development and use of a dynamic modelling framework integrating climate, crop, pasture and livestock models. The framework was applied to a population of 91 farms located in semi-arid Zimbabwe to assess effects on livestock production resulting from climate change and management interventions. Climate scenarios representing relative "cool-wet", "hot-dry" and "middle" conditions by mid-century (2040-2070) for two representative concentration pathways were compared with the baseline climate. On-farm fodder resources and rangeland grass production were simulated with the crop model APSIM and the pasture model GRASP respectively. The simulated fodder availability was used in the livestock model LIVSIM to generate various production indicators including milk, offtake, mortality, manure, and net revenue. We investigated the effects of two adaptation packages targeting soil fertility management and crop diversification and quantified the sensitivity to climate change of both current and improved systems. Livestock productivity was constrained by dry-season feed gaps, which were particularly severe for crude protein and caused by the reliance on rangeland grazing and crop residues, both of low quality in the dry season. Effects on grass and stover production depended on the climate scenario and the crop, but year-to-year variation generally increased. Relative changes in livestock net revenue compared to the baseline climate varied from a 6% increase to a 43% decrease, and the proportion of farmers negatively affected varied from 20% to 100%, depending on the climate scenario. Adverse effects of climate change on average livestock production usually coincided with increased year-to-year variability and risk. Farms with larger stocking density faced more severe feed gaps and were more sensitive to climate change than less densely stocked farms. The first adaptation package resulted in increased stover production and a small increase in livestock productivity. The inclusion of grain and forage legumes with the second package increased milk productivity and net revenues more profoundly by 30%. This was attributed to the alleviation of dry-season feed gaps, which also reduced the sensitivity to climate change compared to the current system. Clearly, individual farms were affected differently by climate change and by improved farm management, illustrating that disaggregated impact assessments are needed to effectively inform decision making towards climate change adaptation.

AbstractDecision makers need accurate information to address climate variability and change and accelerate transformation to sustainability. A stakeholder-driven, science-based multi-model approach has been developed and used by the Agricultural Model Intercomparison and Improvement Project (AgMIP) to generate actionable information for adaptation planning processes. For a range of mid-century climate projections—likely to be hotter, drier, and more variable—contrasting future socio-economic scenarios (Representative Agricultural Pathways, RAPs) were co-developed with stakeholders to portray a sustainable development scenario and a rapid economic growth pathway. The unique characteristic of this application is the integration of a multi-modeling approach with stakeholder engagement to co-develop scenarios and adaptation strategies. Distribution of outcomes were simulated with climate, crop, livestock, and economic impact assessment models for smallholder crop livestock farmers in a typical dryland agro-ecological zone in Zimbabwe, characterized by low and erratic rainfall and nutrient depleted soils. Results showed that in Nkayi District, Western Zimbabwe, climate change would threaten most of the farms, and, in particular, those with large cattle herds due to feed shortages. Adaptation strategies that showed the most promise included diversification using legume production, soil fertility improvement, and investment in conducive market environments. The switch to more legumes in the farming systems reduced the vulnerability of the very poor as well as the more resourced farmers. Overall, the sustainable development scenario consistently addressed institutional failures and motivated productivity-enhancing, environmentally sound technologies and inclusive development approaches. This yielded more favorable outcomes than investment in quick economic wins from commercializing agriculture.

Abstract Mediterranean systems, such as in South Africa, are particularly vulnerable to the predicted increases in mean surface temperatures which will likely affect the growth and physiology of many plants and subsequently affect agricultural productivity. Aspalathus linearis (Burm.f.) R. Dahlgren (rooibos) is an important commercial, endemic crop that is produced in the Cederberg region, South Africa. This region experiences a Mediterranean-type ecosystem that is characterised by hot, dry summers (November – February) and cool, wet winters (May – August). This study assessed the effects of temperature on the growth and stress tolerant traits of A. linearis over two years. Crop biomass and selected physiological traits were determined in the field, along a temperature gradient, at four farm sites in the Cederberg during the summer and winter 2017 and summer 2018. Aspalathus linearis plants showed evidence of transpirational leaf cooling during summer and this, combined with lower chlorophyll and high phenolic content, could be considered acclimatized adaptive changes allowing the plants to mitigate the heating effects of elevated temperatures. Although changes in soil nutrients and increasing temperatures had a negative impact on crop biomass, the phenolic content, a measure of tea quality, did not vary with sites. This suggests that a shift in rooibos farming to cooler and wetter areas further south, for better growth and higher yields, would not compromise the quality of rooibos tea.

Anthropogenic climate change likely influences the beginning of 2020 growing season's water deficit in parts of southern Africa, with severe consequences to food security.

Abstract Seasonal forecasts coupled with crop models can potentially enhance decision-making in smallholder farming in Africa. The study sought to inform future research through identifying and critiquing crop and climate models, and techniques for integrating seasonal forecast information and crop models. Peer-reviewed articles related to crop modelling and seasonal forecasting were sourced from Google Scholar, Web of Science, AGRIS, and JSTOR. Nineteen articles were selected from a search outcome of 530. About 74% of the studies used mechanistic models, which are favored for climate risk management research as they account for crop management practices. European Centre for Medium-Range Weather Forecasts and European Centre for Medium-Range Weather Forecasts, Hamburg, are the predominant global climate models (GCMs) used across Africa. A range of approaches have been assessed to improve the effectiveness of the connection between seasonal forecast information and mechanistic crop models, which include GCMs, analogue, stochastic disaggregation, and statistical prediction through converting seasonal weather summaries into the daily weather. GCM outputs are produced in a format compatible with mechanistic crop models. Such outputs are critical for researchers to have information on the merits and demerits of tools and approaches on integrating seasonal forecast and crop models. There is however need to widen such research to other regions in Africa, crop, farming systems, and policy.

Le changement climatique devrait avoir un impact significatif sur la production agricole en Afrique. Alors qu'un certain nombre d'études ont évalué cet impact en Afrique australe semi-aride ou en Afrique de l'Ouest tropicale, seul un nombre limité s'est intéressé à l'Éthiopie montagneuse et climatiquement variable de l'Afrique de l'Est. Cette étude évalue l'impact du changement climatique sur la production de maïs dans trois sites représentatifs des zones de culture du maïs en Éthiopie. L'évaluation s'appuie sur la simulation du modèle de culture DSSAT du maïs sous le climat actuel et les projections futures (19 modèles climatiques mondiaux et 2 voies de concentration représentatives). La période 1980–2010 a été utilisée pour représenter le climat de référence, tandis que les projections climatiques futures couvrent trois périodes : à court terme (2010–2039), au milieu du siècle (2040–2069) et à la fin du siècle (2070–2099). Des données sur le climat, les sols et la gestion des cultures ont été collectées pour les sites d'étude représentant les zones de culture du maïs dans le pays. Les résultats montrent que les rendements de maïs diminueront jusqu'à 43 et 24% d'ici la fin du siècle dans les stations de Bako et Melkassa, respectivement, tandis que les rendements de maïs simulés à Hawassa montrent une augmentation de 51%. D'une part, la variabilité des précipitations et la hausse des températures sont des facteurs déterminants expliquant la diminution du rendement à Bako et Melkassa, tandis que l'augmentation prévue des précipitations à Hawassa explique les augmentations de rendement simulées. La grande variabilité du terrain et du climat de l'Éthiopie met l'accent sur les réponses extrêmement différentes des systèmes agricoles actuels au changement climatique. Bien que l'adaptation abordée puisse remédier à certains impacts négatifs et, dans certains cas, tirer parti des changements, cette étude révèle que des connaissances locales dédiées sont nécessaires pour que les décideurs nationaux et régionaux puissent répondre avec pertinence locale à une exposition mondiale, afin de faire face aux défis de la sécurité alimentaire. Se espera que el cambio climático tenga un impacto significativo en la producción agrícola en toda África. Si bien varios estudios evaluaron este impacto en el África meridional semiárida o en el África occidental tropical, solo un número limitado se interesó en la Etiopía montañosa y climáticamente variable de África oriental. Este estudio evalúa el impacto del cambio climático en la producción de maíz en tres sitios representativos de áreas de cultivo de maíz en Etiopía. La evaluación se basa en la simulación del modelo de cultivo DSSAT del maíz bajo el clima actual y las proyecciones futuras (19 modelos climáticos globales y 2 vías de concentración representativas). El período 1980–2010 se utilizó para representar el clima de referencia, mientras que las proyecciones climáticas futuras cubren tres períodos; a corto plazo (2010–2039), mediados de siglo (2040–2069) y finales de siglo (2070–2099). Se recopilaron datos de clima, suelo y manejo de cultivos para los sitios de estudio que representan las áreas de cultivo de maíz en el país. Los resultados muestran que los rendimientos de maíz disminuirán hasta en un 43 y 24% para finales de siglo en las estaciones de Bako y Melkassa, respectivamente, mientras que el rendimiento de maíz simulado en Hawassa muestra un aumento del 51%. Por un lado, la variabilidad de las precipitaciones y el aumento de las temperaturas son factores determinantes que explican la disminución del rendimiento en Bako y Melkassa, mientras que el aumento proyectado de las precipitaciones en Hawassa explica los aumentos simulados del rendimiento. La alta variabilidad del terreno y el clima de Etiopía está enfatizando las respuestas extremadamente diferentes de los sistemas agrícolas actuales al cambio climático. Aunque la adaptación abordada puede abordar algunos impactos negativos y, en algunos casos, puede aprovechar los cambios, este estudio revela que es necesario un conocimiento local específico para que los responsables de la toma de decisiones nacionales y regionales respondan con relevancia local a una exposición global, a fin de enfrentar los desafíos de la seguridad alimentaria. Climate change is expected to significantly impact agricultural production across Africa. While a number of studies assessed this impact in semi-arid southern Africa, or tropical West Africa, only a limited number took interest in the mountainous and climatically varying Ethiopia of eastern Africa. This study assesses the impact of climate change on maize production in three representative sites of maize growing areas in Ethiopia. The assessment relies on the DSSAT crop model simulation of maize under current climate and future projections (19 Global Climate Models and 2 Representative Concentration Pathways). The period 1980–2010 was used to represent the baseline climate, while future climate projections cover three periods; near term (2010–2039), mid-century (2040–2069) and end-of-century (2070–2099). Climate, soil and crop management data were collected for the study sites representing the maize growing areas in the country. Results show that maize yields will decrease by up to 43 and 24% by the end of the century at Bako and Melkassa stations, respectively, while simulated maize yield in Hawassa show an increase of 51%. On the one hand, rainfall variability and rising temperatures are determining factors explaining yield decrease in Bako and Melkassa, while projected rainfall increase in Hawassa explain simulated yield increases. The terrain and climate high variability of Ethiopia is emphasizing the extremely different responses of current agricultural systems to climate change. Though adaptation approached can address some negative impacts, and in some case can take advantage of changes, this study reveals that dedicated local knowledge is necessary for national and regional decision makers to respond with local relevance to a global exposure, in order to face food security challenges. من المتوقع أن يؤثر تغير المناخ بشكل كبير على الإنتاج الزراعي في جميع أنحاء أفريقيا. في حين أن عددًا من الدراسات قيمت هذا التأثير في جنوب إفريقيا شبه القاحلة، أو غرب إفريقيا المدارية، إلا أن عددًا محدودًا فقط اهتم بإثيوبيا الجبلية والمتفاوتة مناخيًا في شرق إفريقيا. تقيّم هذه الدراسة تأثير تغير المناخ على إنتاج الذرة في ثلاثة مواقع تمثيلية لمناطق زراعة الذرة في إثيوبيا. يعتمد التقييم على محاكاة نموذج محصول DSSAT للذرة في ظل المناخ الحالي والتوقعات المستقبلية (19 نموذجًا مناخيًا عالميًا ومسارين تمثيليين للتركيز). استخدمت الفترة 1980–2010 لتمثيل المناخ الأساسي، بينما تغطي التوقعات المناخية المستقبلية ثلاث فترات ؛ المدى القريب (2010-2039) ومنتصف القرن (2040-2069) ونهاية القرن (2070–2099). تم جمع بيانات إدارة المناخ والتربة والمحاصيل لمواقع الدراسة التي تمثل مناطق زراعة الذرة في البلاد. تظهر النتائج أن غلة الذرة ستنخفض بنسبة تصل إلى 43 و 24 ٪ بحلول نهاية القرن في محطتي باكو وملكاسا، على التوالي، في حين أن غلة الذرة المحاكاة في هاواسا تظهر زيادة بنسبة 51 ٪. من ناحية، فإن تقلب هطول الأمطار وارتفاع درجات الحرارة هما من العوامل المحددة التي تفسر انخفاض الغلة في باكو وملكاسا، في حين أن الزيادة المتوقعة في هطول الأمطار في هاواسا تفسر زيادات الغلة المحاكاة. تؤكد التضاريس والتغيرات المناخية العالية في إثيوبيا على الاستجابات المختلفة للغاية للنظم الزراعية الحالية لتغير المناخ. على الرغم من أن التكيف الذي تم تناوله يمكن أن يعالج بعض الآثار السلبية، وفي بعض الحالات يمكن أن يستفيد من التغييرات، تكشف هذه الدراسة أن المعرفة المحلية المخصصة ضرورية لصانعي القرار الوطنيين والإقليميين للاستجابة ذات الصلة المحلية للتعرض العالمي، من أجل مواجهة تحديات الأمن الغذائي.