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In Cameroon, as in other countries of the Congo basin region, policy processes and activities related to climate change have been hitherto geared mostly towards mitigation and related questions, with limited concern about adaptation issues. However, the increasing vulnerability of Cameroon to climate variability and change makes adaptation significant to its national climate-change policy. Nonetheless, it remains a challenge to make both adaptation and mitigation occupy the same policy space in Cameroon. This paper builds partly on studies carried out in two community forest carbon initiatives in the southern rainforest of Cameroon. It also argues, supported by existing literature on adaptation and mitigation, that mitigation activities have the potential to produce adaptation outcomes; a situation which avoids duplication of efforts and waste of financial and technical resources, if synergetic options are anticipated and planned. However, whether such integrated approaches succeed and are subsequently reflected in national-level climate policy depends on how actors across different sectors and at different levels engage and carry out their roles. The paper discusses these roles and how they can support each other in pursuing integrated initiatives – a context which is vital for Cameroon.

Global climate change governance has changed substantially in the last decade, with a shift in focus from negotiating globally agreed greenhouse gas (GHG) reduction targets to nationally determined contributions, as enshrined in the 2015 Paris Agreement. This paper analyses trends in adoption of national climate legislation and strategies, GHG targets, and renewable and energy efficiency targets in almost all UNFCCC Parties, focusing on the period from 2007 to 2017. The uniqueness and added value of this paper reside in its broad sweep of countries, the more than decade-long coverage and the use of objective metrics rather than normative judgements. Key results show that national climate legislation and strategies witnessed a strong increase in the first half of the assessed decade, likely due to the political lead up to the Copenhagen Climate Conference in 2009, but have somewhat stagnated in recent years, currently covering 70% of global GHG emissions (almost 50% of countries). In comparison, the coverage of GHG targets increased considerably in the run up to adoption of the Paris Agreement and 89% of global GHG emissions are currently covered by such targets. Renewable energy targets saw a steady spread, with 79% of the global GHG emissions covered in 2017 compared to 45% in 2007, with a steep increase in developing countries. Key policy insightsThe number of countries that have national legislation and strategies in place increased strongly up to 2012, but the increase has levelled off in recent years, now covering 70% of global emissions by 2017 (48% of countries and 76% of global population).Economy-wide GHG reduction targets witnessed a strong increase in the build up to 2015 and are adopted by countries covering 89% of global GHG emissions (76% not counting USA) and 90% of global population (86% not counting USA) in 2017.Renewable energy targets saw a steady increase throughout the last decade with coverage of countries in 2017 comparable to that of GHG targets.Key shifts in national measures coincide with landmark international events – an increase in legislation and strategy in the build-up to the Copenhagen Climate Conference and an increase in targets around the Paris Agreement – emphasizing the importance of the international process to maintaining national momentum. The number of countries that have national legislation and strategies in place increased strongly up to 2012, but the increase has levelled off in recent years, now covering 70% of global emissions by 2017 (48% of countries and 76% of global population). Economy-wide GHG reduction targets witnessed a strong increase in the build up to 2015 and are adopted by countries covering 89% of global GHG emissions (76% not counting USA) and 90% of global population (86% not counting USA) in 2017. Renewable energy targets saw a steady increase throughout the last decade with coverage of countries in 2017 comparable to that of GHG targets. Key shifts in national measures coincide with landmark international events – an increase in legislation and strategy in the build-up to the Copenhagen Climate Conference and an increase in targets around the Paris Agreement – emphasizing the importance of the international process to maintaining national momentum.

The number and sizes of informal settlements are expected to increase drastically in the future, and dramatically so in Sub-Saharan Africa, where migration from rural to urban areas is increasing, and poverty and food insecurity threaten livelihoods. Data sources explaining livelihood factors in informal settlements are scarce, and often highly disputed. In this study, Kibera is investigated, one of the largest informal settlements in Africa. The main aim is to analyze differences in livelihood factors across the villages in Kibera, and to explain some of the existing discrepancies in food security levels among its population. In particular, livelihood factors such as tribe, welfare and trust can explain some of the variation in food security across 12 of the 13 villages located in Kibera. The analyses inform of significant differences across the villages when it comes to, among others, income, food insecurity, ownership of land in rural areas, tribal background and trust levels in strangers and community leads. To reach the millions of people living in informal settlements now, and increasingly so in the future, it is advised that research and implementation go hand in hand, with enhanced understanding of the complexities within rural–urban food systems to ensure solutions that are affordable and accessible to low-income groups. On this pathway to fight poverty and hunger in the future, today’s policies and programs must take such complexities into account to positively contribute to strengthening the resiliency and sustainability of rural–urban food systems by ensuring an increase in welfare levels with zero climate impact.

L'intensification durable a été proposée comme moyen d'atteindre la sécurité alimentaire et de réduire les impacts environnementaux de l'agriculture en se concentrant sur la réduction des écarts de rendement sur les terres agricoles existantes tout en améliorant l'efficacité de l'utilisation des ressources. Il existe un consensus général sur le fait que les régions présentant de grands écarts de rendement peuvent bénéficier le plus d'une intensification durable, mais il n'est pas clair dans quelle mesure cela est durable pour les agriculteurs compte tenu de leurs contraintes actuelles en matière de ressources et de leurs stratégies de subsistance. Ici, nous nous appuyons sur trois études de cas contrastées, pour lesquelles des données détaillées au niveau des champs et des exploitations étaient disponibles pour la décomposition des écarts de rendement, afin d'évaluer le fonctionnement de l'intensification durable des cultures (au niveau des champs) au niveau des exploitations à l'aide d'indicateurs environnementaux et socio-économiques. Bien qu'il existe un grand potentiel d'intensification future (plus de production avec plus d'intrants) de la production céréalière dans le sud de l'Éthiopie, l'utilisation actuelle des intrants dans ces systèmes agricoles n'est pas durable sur les plans économique et environnemental au niveau des exploitations. Il en va de même pour la production de riz dans le centre de Luçon, où une intensification durable (plus de production avec moins d'intrants) peut aider à réduire les écarts de rendement et à améliorer l'efficacité de l'utilisation de l'azote (nue), mais elle n'est pas rentable en raison de la forte dépendance à une main-d' œuvre embauchée coûteuse. Des compromis entre la réduction de l'écart de rendement et la productivité du travail ont également été observés dans les systèmes agricoles susmentionnés. Les fermes arables aux Pays-Bas présentent de faibles écarts de rendement ainsi que des performances économiques, des nue et des excédents d'azote plus élevés que ceux observés dans le sud de l'Éthiopie et le centre de Luçon. Pour améliorer la durabilité environnementale, ces exploitations nécessitent des augmentations de l'efficacité de l'utilisation des ressources et une réduction des impacts environnementaux grâce à une utilisation moindre des intrants (même production avec moins d'intrants). Nous concluons que les investissements publics propices à l'innovation et à une agriculture rentable sont essentiels pour rendre les technologies accessibles et abordables pour les agriculteurs et pour veiller à ce que les écarts de rendement puissent être réduits et que les objectifs de durabilité soient atteints au niveau des exploitations. La intensificación sostenible se ha propuesto como una vía para lograr la seguridad alimentaria y reducir los impactos ambientales de la agricultura, centrándose en reducir las brechas de rendimiento en las tierras agrícolas existentes al tiempo que se mejora la eficiencia en el uso de los recursos. Existe un consenso general de que las regiones con grandes brechas de rendimiento pueden beneficiarse más de la intensificación sostenible, pero no está claro qué tan sostenible es esto para los agricultores dadas sus actuales limitaciones de recursos y estrategias de medios de vida. Aquí, nos basamos en tres estudios de casos contrastantes, para los cuales se disponía de datos detallados a nivel de campo y granja para la descomposición de la brecha de rendimiento, para evaluar cómo funciona la intensificación sostenible de los cultivos (a nivel de campo) a nivel de granja utilizando indicadores ambientales y socioeconómicos. Aunque existe un gran potencial para la intensificación futura (más producción con más insumos) de la producción de cereales en el sur de Etiopía, el uso actual de insumos en estos sistemas agrícolas no es económica y ambientalmente sostenible a nivel de granja. Lo mismo ocurre con la producción de arroz en Luzón Central, donde la intensificación sostenible (más producción con menos insumos) puede ayudar a reducir las brechas de rendimiento y mejorar la eficiencia del uso del N (nue), pero no es rentable debido a la gran dependencia de la costosa mano de obra contratada. También se observaron compensaciones entre el cierre de la brecha de rendimiento y la productividad laboral en los sistemas agrícolas mencionados anteriormente. Las granjas cultivables en los Países Bajos exhiben pequeñas brechas de rendimiento, así como un mayor rendimiento económico, superávit de nue y N en comparación con las observadas en el sur de Etiopía y el centro de Luzón. Para mejorar la sostenibilidad ambiental, estas granjas requieren aumentos en la eficiencia del uso de los recursos y una reducción de los impactos ambientales a través de un menor uso de insumos (mismo producto con menos insumos). Concluimos que las inversiones públicas propicias para la innovación y la agricultura rentable son esenciales para que las tecnologías sean accesibles y asequibles para los agricultores y para garantizar que las brechas de rendimiento se puedan reducir y que los objetivos de sostenibilidad se cumplan a nivel de granja. Sustainable intensification has been proposed as a pathway to achieve food security and reduce environmental impacts of agriculture by focusing on narrowing yield gaps on existing agricultural land while improving resource use efficiencies. There is a general consensus that regions with large yield gaps can benefit most from sustainable intensification but it remains unclear how sustainable this is for farmers given their current resource constraints and livelihood strategies. Here, we draw upon three contrasting case studies, for which detailed data at field and farm levels were available for yield gap decomposition, to assess how sustainable intensification of crops (at field level) works out at farm level using environmental and socio-economic indicators. Although there is large potential for future intensification (more output with more input) of cereal production in southern Ethiopia, current input use in these farming systems is not economically and environmentally sustainable at farm level. The same is true for rice production in Central Luzon where sustainable intensification (more output with less input) can help to narrow yield gaps and improve N use efficiency (NUE) but it is not profitable due to the heavy reliance on costly hired labour. Trade-offs between yield gap closure and labour productivity were also observed in the aforementioned farming systems. Arable farms in the Netherlands exhibit small yield gaps as well as higher economic performance, NUE and N surplus compared to those observed in Southern Ethiopia and Central Luzon. For improving environmental sustainability, these farms require increases in resource-use efficiency and a reduction of the environmental impacts through a lower use of inputs (same output with less input). We conclude that public investments conducive for innovation and profitable farming are essential to make technologies accessible and affordable for farmers and to ensure that yield gaps can be narrowed and sustainability objectives served at the farm level. تم اقتراح التكثيف المستدام كمسار لتحقيق الأمن الغذائي والحد من الآثار البيئية للزراعة من خلال التركيز على تضييق فجوات الغلة على الأراضي الزراعية الحالية مع تحسين كفاءة استخدام الموارد. هناك إجماع عام على أن المناطق التي تعاني من فجوات كبيرة في المحاصيل يمكن أن تستفيد أكثر من التكثيف المستدام ولكن لا يزال من غير الواضح مدى استدامة ذلك بالنسبة للمزارعين نظرًا لقيود الموارد الحالية واستراتيجيات سبل العيش. هنا، نعتمد على ثلاث دراسات حالة متناقضة، حيث كانت البيانات التفصيلية على مستوى الحقل والمزرعة متاحة لتحليل فجوة الغلة، لتقييم كيفية عمل التكثيف المستدام للمحاصيل (على مستوى الحقل) على مستوى المزرعة باستخدام المؤشرات البيئية والاجتماعية والاقتصادية. على الرغم من وجود إمكانات كبيرة للتكثيف المستقبلي (المزيد من الإنتاج مع المزيد من المدخلات) لإنتاج الحبوب في جنوب إثيوبيا، فإن الاستخدام الحالي للمدخلات في هذه النظم الزراعية ليس مستدامًا اقتصاديًا وبيئيًا على مستوى المزرعة. وينطبق الشيء نفسه على إنتاج الأرز في وسط لوزون حيث يمكن أن يساعد التكثيف المستدام (المزيد من المخرجات مع مدخلات أقل) في تضييق فجوات الغلة وتحسين كفاءة الاستخدام (NUE) ولكنه ليس مربحًا بسبب الاعتماد الكبير على العمالة المستأجرة المكلفة. كما لوحظت مفاضلات بين إغلاق فجوة العائد وإنتاجية العمل في النظم الزراعية المذكورة أعلاه. تُظهر المزارع الصالحة للزراعة في هولندا فجوات صغيرة في الغلة بالإضافة إلى أداء اقتصادي أعلى وفائض NUE و N مقارنة بتلك التي لوحظت في جنوب إثيوبيا ووسط لوزون. ولتحسين الاستدامة البيئية، تتطلب هذه المزارع زيادات في كفاءة استخدام الموارد وتقليل الآثار البيئية من خلال استخدام أقل للمدخلات (نفس المخرجات مع مدخلات أقل). نستنتج أن الاستثمارات العامة التي تفضي إلى الابتكار والزراعة المربحة ضرورية لجعل التقنيات في متناول المزارعين وبأسعار معقولة ولضمان تضييق فجوات الغلة وتحقيق أهداف الاستدامة على مستوى المزرعة.

In view of pressing unemployment problems, policy makers across all parties jump on the prospects of renewable energy promotion as a job creation engine which can boost economic well-being. Our analytical model shows that initial labor market rigidities in theory provide some scope for such a double dividend. However, the practical outcome of renewable energy promotion might be sobering. Our computable general equilibrium analysis of subsidized electricity production from renewable energy sources (RES-E) in Germany suggests that the prospects for employment and welfare gains are quite limited and hinge crucially on the level of the subsidy rate and the financing mechanism. If RES-E subsidies are financed by labor taxes, welfare and employment effects are strictly negative for a broad range of subsidy rates. The use of an electricity tax to fund RES-E subsidies generates minor benefits for small subsidy rates but these benefits quickly turn into significant losses as the subsidy rate exceeds some threshold value.

Ester production by microorganisms is of great importance to biotechnological processes. These volatile compounds impart pleasant, fruity aromas to beer, wine, and other fermented products. Yeast in particular are well known for their ability to produce volatile esters. The genetic and enzymatic intricacies of ester production have been the focus of many studies, mainly in S. cerevisiae. Despite this, ester synthesis in yeast is not fully understood. This holds particularly true for yeasts that produce high amounts of ethyl acetate from sugars, such as Kluyveromyces marxianus and Wickerhamomyces anomalus. As was introduced in Chapter 1, this ability has been described more than a century ago, but the enzymatic mechanisms behind the synthesis were unclear. Circumstantial evidence suggested that an alcohol acetyltransferase (AAT) was responsible for the ethyl acetate formation. Ethyl acetate is a versatile commodity chemical that is currently produced in unsustainable processes. Understanding the enzymes responsible for bulk ethyl acetate synthesis in yeast could enable rational design of novel production strains. This, in turn could facilitate the development of biobased ethyl acetate production processes. This thesis has made several important breakthroughs in the field of ester production in yeast, particularly ethyl acetate. The most significant of these was the discovery of the elusive enzyme responsible for bulk ethyl acetate synthesis in yeast. The identification of the ethyl acetate-producing enzyme in W. anomalus is described in Chapter 2. The purified enzyme showed AAT activity with ethanol and acetyl-CoA and was therefore named Ethanol acetyltransferase 1 (Eat1). Production of Eat1 in Escherichia coli enabled efficient ethyl acetate production in E. coli. The enzyme could thus potentially be used to develop new biobased ethyl acetate production processes. However, Eat1 was also able to function as a thioesterase and esterase active against acetyl-CoA and ethyl acetate, respectively. It was observed that the presence of ethanol was able to repress the hydrolytic activities, at which point the AAT activity was dominant. How ethanol can control the activities of Eat1 is unclear. It highlights that sufficient ethanol concentrations must be present to produce ethyl acetate with Eat1. It is also shown that Eat1 homologs are present in other bulk ethyl acetate-producing yeasts. These homologs are only distantly related to known AATs. Eat1 is therefore proposed to compose a novel alcohol acetyltransferase family. The discovery of this novel enzyme family was the cornerstone of the research presented in this thesis. The identification enabled further studies on the physiology of Eat1 and bulk ethyl acetate production in the native yeasts in Chapter 3. The cellular location of Eat1 in Kluyveromyces lactis was determined. The enzyme localised to the mitochondria of the yeast. This observation opposed the literature consensus which assumed that bulk ethyl acetate synthesis occurred in the yeast cytosol. Cytosolic acetyl-CoA flux in yeast is low and would presumably not support the synthesis of high amounts of ethyl acetate. The localisation of Eat1 in the mitochondria could better explain how bulk ethyl acetate synthesis occurs. The current hypothesis suggests that bulk ethyl acetate is an overflow product of yeast under iron limited conditions. Under these conditions, the entry of acetyl-CoA into the TCA cycle is impaired and acetyl-CoA accumulates. Eat1 is then proposed to relieve the accumulation by forming ethyl acetate. The TCA cycle and the major flux of acetyl-CoA in yeast are located in the mitochondria, where Eat1 is also located. It is thereby established that bulk ethyl acetate is a mitochondrial product of certain yeasts. Chapter 4 describes the engineering of efficient ethyl acetate production in E. coli using Eat1 as the catalyst. Unlike yeast, the metabolism of E. coli can support the synthesis of ethyl acetate under anaerobic conditions. This removes the need for aeration, which is costly on a large scale. Establishing the anaerobic ethyl acetate pathway was faced with several bottlenecks, and removing them was the main theme of this chapter. The pathway towards ethyl acetate could be improved by disrupting by-product formation and optimising the expression levels of eat1. Further improvements could be made by removing the N-terminal mitochondrial localisation sequence of Eat1. These sequences typically destabilise proteins unless they are removed. These approaches did improve ethyl acetate formation by Eat1 to the point where ethanol levels were no longer sufficient to repress the hydrolytic activities of Eat1. To prevent ester hydrolysis the volatility of ethyl acetate was used to strip it from the fermenter. The result was ethyl acetate production at 63.4 % of the pathway maximum. We then looked beyond ethyl acetate as a bulk chemical in Chapter 5 and investigated the role Eat1 has in general ester formation by yeasts, particularly S. cerevisiae. The formation of esters is industrially relevant also in S. cerevisiae as these compounds contribute to the aroma of fermented foods. S. cerevisiae naturally produces a variety of alcohols and thus provided a convenient platform to compare Eat1 homologs from different yeast. Expression of various eat1 genes resulted in an increase of various in acetate and propionate ester levels. By disrupting the S. cerevisiae eat1 gene the inverse effect was observed. Eat1 therefore seems to contribute to acetate ester synthesis in S. cerevisiae as well. In this chapter, a S. cerevisiae strain was generated where all known AAT genes were disrupted. Opposite to the expectations, ester production persisted in this strain, showing that even more ester-producing mechanisms exist. Chapter 6 focuses on the complex field of ester production as bulk chemicals, from the fundamentals of microbial ester production. Much research has been devoted to understanding the ester-producing processes in microorganisms. This is a daunting task as the structures and functions of esters in microorganisms are in many cases unrelated. Most esters are produced via the AAT reaction. With the exception of Eat1, which was identified in this thesis, other AATs have been studied for a long time. Still, relatively little is known about their structure and catalytic mechanisms, likely because there are no crystal structures available yet. Nevertheless, they have been applied extensively in metabolic engineering of ester production. The AAT reaction is simple. As long as a suitable alcohol and acyl-CoA are provided, the AAT will catalyse the ester formation. The real challenge of engineering ester formation is in the efficient supply of alcohols and acyl-CoA substrates. Some remarkable success has been made in recent years which is outlined in the review. In many cases, esters are less toxic and more readily extractable than the alcohols and acids they are composed of. They could therefore serve as a platform compound. In summary, this thesis contributed significantly to the knowledge of ester synthesis in yeast. The progress made on the production of ethyl acetate specifically can be used to develop new biotechnological, more sustainable production processes for this versatile compound. At the same time, much remains to be discovered.

In recent years there has been increasing attention to the transition toward a bioeconomy. From comparable transitions toward sustainability, we know that transitions require integral, inclusive approaches toward developing a long-term strategy, focusing not only on technological innovation, but also on involving the public. This is not easy. Public engagement encompasses diverse forms of public and civil society participation, and it is crucial to understand the specificities of these interactions and their effects on potential transition pathways. We present a conceptual-analytical paper where the focus lies on understanding sense-making practices in the construction of publics in the bioeconomy. Using a case-study approach, this article describes five partialities of the constructed public in the bioeconomy and analyzes the orchestration, productive dimensions and effects of these constructions. Our analysis offers a new perspective on, and appreciation of, the partiality of different forms of public participation, and varying degrees in which possibilities of system change in the bioeconomy transition are inclusive or exclusive toward differentially constructed publics. This offers an alternative, constructive way of exploring actor dynamics and politics in system change. We aim to contribute to a more nuanced and integral interpretation of public engagement in sustainability transitions, which is relevant to actors from academia, policy, industry and other spheres relevant to the bioeconomy transition.