Scientific publications

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West Paul C, Gerber James S, Engstrom Peder M, Mueller Nathaniel D, Brauman Kate A, Carlson Kimberly M, Cassidy Emily S, Johnston Matt, MacDonald Graham K, Ray Deepak K, Siebert Stefan. 2014. Leverage points for improving global food security and the environment. Science

Achieving sustainable global food security is one of humanity’s contemporary challenges. Here we present an analysis identifying key “global leverage points” that offer the best opportunities to improve both global food security and environmental sustainability. We find that a relatively small set of places and actions could provide enough new calories to meet the basic needs for more than 3 billion people, address many environmental impacts with global consequences, and focus food waste reduction on the commodities with the greatest impact on food security. These leverage points in the global food system can help guide how nongovernmental organizations, foundations, governments, citizens’ groups, and businesses prioritize actions.

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Webber Heidi, Gaiser Thomas, Ewert Frank. 2014. What role can crop models play in supporting climate change adaptation decisions to enhance food security in Sub-Saharan Africa?. Agricultural Systems

In Sub-Saharan Africa (SSA) efforts to achieve food security are challenged by poverty, low soil fertility, unequal global trade relationships, population growth, weak institutions and infrastructure, and future climate changes and variability. Crop models are the primary tools available to assess the impacts of climate change and other drivers on crop productivity, a key aspect of food security. This review examines their role and suitability for informing climate change adaptation decisions in the SSA context. Perception of climate change is rarely the only factor leading to changed farming practices, with labor availability, recent extreme climatic events (floods or droughts) and access to formal credit, constituting the main factors farmers respond to. Further, farmers’ socio-economic status constrains the adaptations they make in response to these drivers. Many crop modeling studies reviewed investigating climate change adaptation currently do not capture many of these drivers, adaptations nor constraints. However, a number of areas were identified where crop models could aid in adaptations decision-making. For instance, crop models can: test which changes farmers are making are most robust to future climate scenarios; be used as tools for experimentation in farmer organizations to build farmer capacity, minimize risk and empower farmers; be linked to economic, farm systems or livestock models to widen the scope of potential impacts, adaptations and farmer constraints considered, and to probe the interactions of cropping systems with other systems; and evaluate various indicators of resilience. Finally it is suggested that one of the greatest benefits of linking crop models across disciplines and in integrated assessment frameworks may be providing a platform to bring specialists and stakeholders from diverse backgrounds together to assess climate change adaptation options to enhance food security in SSA.

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Virchow Detlef, Beuchelt Tina, Denich Manfred, Loos Tim K, Hoppe Marlene, Kuhn Arnim. 2014. The value web approach so that the South can also benefit from the bioeconomy. Rural 21

The rising demand for biomass is transforming agriculture from a food to a complex biomass-supplying and -processing sector, which the countries of the South could benefit from. New prospects could arise for them to go beyond their role of pure raw material suppliers. However, a value chain approach is insufficient in this context. The biomassbased value web appears to offer an alternative approach.

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Virchow D, Beuchelt Tina, Kuhn A, Denich M. 2016. Biomass-Based Value Webs: A Novel Perspective for Emerging Bioeconomies in Sub-Saharan Africa. Springer Open (eds.). Technological and Institutional Innovations for Marginalized Smallholders in Agricultural Development. ZEF: 225-238 pp.

Growing demand for increasingly diverse biomass-based products will transform African agriculture from a food-supplying to a biomass-supplying sector, including non-food agricultural produce, like feed, energy and industrial raw materials. As a result, agriculture will become the core part of a biomass-based economy, which has the potential not only to produce renewable biological resources but to convert this biomass into products for various uses. The emerging bioeconomy will intensify the interlinkages between biomass production, processing and trading. To depict these increasingly complex systems, adapted analytic approaches are needed. With the perspective of the “biomass-based value web” approach, a multi-dimensional methodology can be used to understand the interrelation between several value chains as a flexible, efficient and sustainable production, processing, trading and consumption system.

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Trawally D.M.A, Webber H, Agyare W A, Fosu M, Naab J, Gaiser Thomas. 2015. Modelling heat stress effect on two maize varieties in Northern Region of Ghana. Global Advanced Research Journal of Agricultural Science

Agriculture in Ghana accounts for more than 30% of GDP and three-quarters of export earnings. In Sub-Saharan Africa, climate change is predicted to affect the agricultural sector most. The objectives of this study were: to use the SIMPLACE (Scientific Impact assessment and Modelling Platform for Advanced Crop and Ecosystem management) to simulate maize yield under heat stress. To compare SIMPLACE model output with heat stress, and without heat stress. Finally simulate the effect of heat stress on maize yield depending on the sowing date. The study collected and analysed data from field experiments during the 2012/2013 dry season and repeated in 2014 at Botanga irrigation site and the 2014 rainy season at Gbulahagu farming community based on three (3) sowing dates (SD). Comparing the SIMPLACE model output to the observed field data, the duration of development phases were predicted with acceptable accuracy among the three sowing dates. Simulated and observed showed good agreement for maize biomass at several growth stages of the maize. The heat stress component of SIMPLACE gave a good prediction for yield under heat stress when no other stress (water, nutrients) occurred. The estimations of the final yield showed an over estimation when the model was run with no heat stress condition in the rainy season experiment in particular under nutrient stress. The model was successfully parameterized and evaluated for simulating the effect of heat stress on maize yield under no nutrient and drought stress and can therefore be used as a research tool in the study area.

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Siebert Stefan, Ewert Frank. 2014. Future crop production threatened by extreme heat. Environmental Research Letters

Heat is considered to be a major stress limiting crop growth and yields. While important findings on the impact of heat on crop yield have been made based on experiments in controlled environments, little is known about the effects under field conditions at larger scales. The study of Deryng et al (2014 Global crop yield response to extreme heat stress under multiple climate change futures Environ. Res. Lett. 9 034011), analysing the impact of heat stress on maize, spring wheat and soya bean under climate change, represents an important contribution to this emerging research field. Uncertainties in the occurrence of heat stress under field conditions, plant responses to heat and appropriate adaptation measures still need further investigation.

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Porkka Miina, Kummu Matti, Siebert Stefan, Varis Olli. 2013. From food insufficiency towards trade dependency: a historical analysis of global food availability. PLoS One

Achieving global food security is one of the major challenges of the coming decades. In order to tackle future food security challenges we must understand the past. This study presents a historical analysis of global food availability, one of the key elements of food security. By calculating national level dietary energy supply and production for nine time steps during 1965–2005 we classify countries based on their food availability, food self-sufficiency and food trade. We also look at how diets have changed during this period with regard to supply of animal based calories. Our results show that food availability has increased substantially both in absolute and relative terms. The percentage of population living in countries with sufficient food supply (>2500 kcal/cap/d) has almost doubled from 33% in 1965 to 61% in 2005. The population living with critically low food supply (<2000 kcal/cap/d) has dropped from 52% to 3%. Largest improvements are seen in the MENA region, Latin America, China and Southeast Asia. Besides, the composition of diets has changed considerably within the study period: the world population living with high supply of animal source food (>15% of dietary energy supply) increased from 33% to over 50%. While food supply has increased globally, food self-sufficiency (domestic production>2500 kcal/cap/d) has not changed remarkably. In the beginning of the study period insufficient domestic production meant insufficient food supply, but in recent years the deficit has been increasingly compensated by rising food imports. This highlights the growing importance of food trade, either for food supply in importing countries or as a source of income for exporters. Our results provide a basis for understanding past global food system dynamics which, in turn, can benefit research on future food security.

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