Open Access

Das 21. Jahrhundert wird auch als „urban century“ bezeichnet. Der Stadtraum bietet einerseits „enger verknüpfte Kommunikationsräume und damit einen verbesserten Zugang zu Informationen aller Art“, „höheres soziales Kapital, mehr Raum für persönliche Entfaltung, Vielfalt und Innovation“ sowie „verbesserte Möglichkeiten der Teilhabe“. Andererseits sind auch Stress-faktoren, „wie Lärm und Umweltverschmutzung“, verstärkt im städtischen Raum vertreten. Zunehmend beeinträchtigen Extremwetterereignisse, wie Hitze- und Starkregen, den Lebensraum Stadt und das Wohlbefinden der Menschen. Zusätzlichen Wohnraum für mehr Menschen zu schaffen, stößt in der Stadt- und Raumplanung auf Maßnahmen zur Klimafolgenanpassung. Erholungs- und Aktivitätsräume stehen in Konkurrenz zum Ausbau der Infrastruktur, wie dem Wohnungs- und Straßenbau. Es wird zudem die Notwendigkeit für transdisziplinäre Diskurse und Arbeitsweisen im Rahmen einer klimawandelgerechten Stadtentwicklung hergeleitet. Ziel ist die Erarbeitung von Potentialen, die sich in Lüneburg für eine Begrünung der Innenstadt bieten, um dem sich wandelnden Klima zu begegnen, sowie herauszuarbeiten welche Akteur*innen, Schlüsselfaktoren und -elemente die Umsetzung von Begrünungsmaßnahmen einschränken oder stärken. Mit der Methode der Konstellationsanalyse sollen zukunftsgerichtete und zentrale Handlungsfelder verdeutlicht werden. Es soll die Basis für eine erfolgreiche und nachhaltige Arbeitsweise sowie Zusammenarbeit im Bereich der Klimafolgenanpassung in Lüneburg gelegt werden.

Both sustainability and transdisciplinary research can change academic research, especially with regard to its relevance for, and relationship with, its environments. Transdisciplinary sustainability research (TSR), thus, offers the opportunity to change non-sustainable development paths of sciences themselves. In order to fully exploit this possibility, this PhD project addresses the question of how TSR, in the first place, does conceptualize and, in the second place, could conceptualize knowledge, research, and science. Firstly, this PhD project analyzes, from a discourse studies perspective, the term problem in TSR, against the background of discourses on sustainable development. Secondly, it explores the historicalanalytical and transformative concept of the problematic. The results, firstly, show the consequences of a problem-solving focus for TSR, and secondly, differentiate it from a transformative direction of problematic designing, as a more appropriate view on the dimensions of transformation and their qualities of change that matter for TSR. This PhD project aims to contribute to a self-understanding of, and a philosophical communication about, TSR, as a research form in the sustainability sciences. Keywords: Discourse studies, problem-solving, transdisciplinary sustainability research, transformative potential, dimensions of transformation.

The world currently faces important issues concerning climate change and environmental sustainability, with the wellbeing of billions of people around the world at risk over the next decades. Existing institutions no longer appear to be sufficiently capable to deal with the complexity and uncertainty associated with the wicked problem of sustainability. Achieving the required sustainability transformation will thus require purposeful reform of existing institutional frameworks. However, existing research on the governance of sustainability of sustainability transformations has strongly focused on innovation and the more ‘creative’ aspects of these processes, blinding our view to the fact that they go hand with the failure, decline or dismantling of institutions that are no longer considered functional or desirable. This doctoral dissertation thus seeks to better understand how institutional failure and decline can contribute productively to sustainability transformations and how such dynamics in institutional arrangements can serve to restructure existing institutional systems. A systematic review of the conceptual literature served to provide a concise synthesis of the research on ‘failure’ and ‘decline’ in the institutional literature, providing important first insights into their potentially productive functions. This was followed up by an archetype analysis of the productive functions of failure and decline, drawing on a wide range of literatures. This research identified five archetypical pathways: (1) crises triggering institutional adaptations toward sustainability, (2) systematic learning from failure and breakdown, (3) the purposeful destabilisation of unsustainable institutions, (4) making a virtue of inevitable decline, and (5) active and reflective decision making in the face of decline instead of leaving it to chance. Empirical case studies looking at the German energy transition and efforts to phase out coal in the Powering Past Coal Alliance served to provide more insights on (a) how to effectively harness ‘windows of opportunity’ for change, and (b) the governance mechanisms used by governments to actively remove institutions. Results indicate that the lock-in of existing technologies, regulations and practices can throw up important obstacles for sustainability transformations. The intentional or unintentional destabilisation of the status quo may thus be required to enable healthy renewal within a system. This process required active and reflective management to avoid the irreversible loss of desirable institutional elements. Instruments such as ‘sunset clauses’ and ‘experimental legislation’ may serve as important tools to learn through ‘trial and error’, whilst limiting the possible damage done by failure. Focusing on the subject of scale, this analysis finds that the level at which failure occurs is likely to determine the degree of change that can be achieved. Failures at the policy-level are most likely to merely lead to changes to the tools and instruments used by policy makers. This research thus suggests that failures on the polity- and political level may be required to achieve transformative changes to existing power structures, belief-systems and paradigms. Finally, this research briefly touches on the role of actor and agency in the governance of sustainabilitytransformations through failure and decline. It finds that actors may play an important role in causing a system or one of its elements to fail and in shaping the way events are come to be perceived. Drawing on the findings of this research, this dissertation suggests a number of lessons policy makers and others seeking to revisit existing institutional arrangements may want to take into account. Actors should be prepared to harness the potential associated with failure and decline, preserve those institutional elements considered important, and take care to manage the tension between the need for ‘quick fixes’ to currently pressing problems and solution that maintain and protect the longterm sustainability of a system.

Wind energy is expected to become the largest source of electricity generation in Europe’s future energy mix with offshore wind energy in particular being considered as an essential component for secure and sustainable energy supply. As a consequence, future electricity generation will be exposed to an increasing degree to weather and climate. With planning and operational lifetimes of wind energy infrastructure reaching climate time scales, adaptation to changing climate conditions is of relevance to support secure and sustainable energy supply. Premise for success of wind energy projects is the ability to service financial obligations over the project lifetime. Though, revenues(viaelectricity generation) are exposed to changing climate conditions affecting the wind resource, operating conditions or hazardous events interfering with the wind energy infrastructure. For the first time, a procedure is presented to assess such climate change impacts specifically for wind energy financing. At first, a generalised financing chain for wind energy is prepared to(qualitatively) trace the exposure of individual cost elements to physical climate change. In this regard, the revenue through wind power production is identified as the essential component within wind energy financing being exposed to changing climate conditions. This implies the wind resource to be of crucial interest for an assessment of climate change impacts on the financing of wind energy. Therefore, secondly, a novel high-resolution experimental modelling framework with the non-hydrostatic extension of the regional climate model REMO is set up to generate physically consistent climate and climate change information of the wind resource across wind turbine operating altitudes. With this setup, enhanced simulated intra-annual and inter-annual variability across the lower planetary boundary layer is achieved, being beneficial for wind energy applications, compared to state-of-the-art regional climate model configurations. In addition, surrogate climate change experiments with this setup disclose vertical wind speed changes in the lower planetary boundary layer to be indirectly affected by temperature changes through thermodynamically-induced atmospheric stability alterations. Moreover, air density changes are identified to occasionally exceed the net impact of wind energy density changes originating from changes in wind speed. This supports the consideration of air density information (in addition to wind speed) for wind energy yiel assumptions. Thirdly, the generated climate and climate change information of the wind resource are transferred to a simplified but fully-fledged financial model to assess the financial risk of wind energy project financing with respect to changing climate conditions. Sensitivity experiments for an imaginary offshore wind farm located in the German Bight reveal the long-term profitability of wind energy project financing not to be substantially affected by changing wind resource conditions, but incidents with insufficient servicing of financial obligations experience changes exceeding -10% to 14%. The integration of wind energy-specific climate and climate change information into existing financial risk assessment procedures would illustrate a valuable contribution to enable climate change adaptation for wind energy. In particular information about intra-annual and inter-annual variability change of the wind resource originating from changing climate conditions permit the quantification of additional financial risk associated to debt repayment obligations and, subsequently, enable the development of suitable preventive economic measures. Though, additional efforts in combination with future technical development are necessary to provide essential additional information about the bandwidth of climate change and uncertainties associated to such sector-specific climate and climate change information.

This doctoral research is located in the branch of sustainability sciences that has the realisation of sustainable development as its core subject of research. The most broadly accepted notion of sustainable development is that which evolves along the resolutions, declarations, and reports from international processes in the framework of the United Nations (UN). The consensual outputs from such processes feature global-generalised and context-free perspectives. However, implementation requires action at diverse and context-rich local levels as well. Moreover, while in such UN processes national states are the only contractual parties, it is increasingly recognised that other (‘nonstate’) actors are crucial to sustainability. The research presented here places the attention on bottom-up initiatives that are advancing innovative ways to tackle universal access to clean energy and to strengthen small-scale family farmers. This means, the focus is on bottom-up initiatives advancing local implementation of global sustainability targets, more precisely, targets that make part of the Sustainable Development Goals two and seven (SDG 2 and SDG7). The research asks how such bottom-up initiatives can contribute to the diffusion of sustainability innovations, thereby also contributing to social change. Three aims are derived out of that central question: • Analytical: To understand the role of bottom-up initiatives in the diffusion of sustainability innovations and in the thereby involved social changes. • Transformative: To contribute with my research to the actual diffusion of sustainability innovations. • Methodological: To outline a research approach that provides a solid conceptual and methodological framework for attaining the analytical and transformative aims. Conceptually, the research builds on theoretical insights from diverse strands of the broad field of sustainability transitions – mostly on conceptualisations from transition management, strategic niche management, and grassroots innovations – as well as on conceptual and methodological advances in transdisciplinary and in transformative research. The doctoral research comprises four single studies, in which the notion of diffusion is explored at different scopes of social scales. It begins with a thorough analysis of diffusion programs of domestic biodigesters to rural households in countries of the global south. The focus is on the process by which this specific technical inno0vation results integrated (or not) into the daily realities of single rural households, that is, the adoption process. In the second study, the attention is on energy supply models based on different decentralised renewable technologies. Central to these models is the building of new (or strengthening of existing) local socioeconomic structures that can assume and ensure the proper operation and supply of energy services. The interest in this study is on the strategies that organisations implementing community-based energy projects apply to support the realisation of such local structures. The third study focuses on a network of bottom-up initiatives that have been advancing alternative approaches to family farming in Colombia. The network mainly comprises farmers associations, other organisations from civil society, and researchers who had been collaborating and experimenting with innovations in different innovation fields such as technical, organisational, financial, and commercialisation schemes. The aim of this third study is to provide insights into the challenges and difficulties faced by these actors in broadening the diffusion of the innovations they have been advancing. To perform this study, a methodological strategy is applied that combines a transdisciplinary mutual learning format with qualitative content analysis techniques. The fourth and last study is a conceptual disquisition. It develops a conceptual framework that (a) provides better accounts for the particularities of endeavours aimed at the diffusion of knowledge and practices from the bottom-up across local contexts and social scales, and (b) advances first conceptual steps towards an explicit account for the role that innovation research (and innovation researchers) can assume for the actual realisation of diffusion. The main findings or contributions of the doctoral research can be categorised into four subjects: 1) Bottom-up initiatives contribute to the diffusion of sustainable innovations by: (a) mobilising transformative resources for inducing diffusion in their scope of action; both their own as well as others’ resources; and (b) creating spaces for experimentation in which interventions can be tested (and if necessary adjusted) in order to ensure the proper deployment of innovations. 2) In their efforts to advance the diffusion of sustainability innovations, bottom-up initiatives contribute to social changes for (a) ensuring the effective deployment of the innovations, for instance: • by supporting change in the sociotechnical configurations that enable and constrain the daily practices of single households, in a way that permits the innovation’s proper operation; and • by reshaping local socioeconomic structures in order to ensure and sustain the supply of services and goods linked to the implemented innovation; (b) building local available storage of transformative resources, that is, the consolidation of local organisational structures that facilitate the building and binding of knowledge, financial capital, people’s skills, access to networks among other resources. Moreover, knowledge and practices from the bottom-up can transit to other social scales, and in this way contribute to social changes beyond their localities. 3) A conceptualisation of innovation diffusion, in which the work of academic researchers studying innovation is a constitutive part of transdisciplinary knowledge articulations that promote diffusion. In this way transdisciplinary research alliances can be envisioned in which researchers investigate about, with, and for bottom-up initiatives. 4) Contributions to the consolidation, systematisation, and dissemination of strategies that are applied by farmers associations in order to strength the economic, social, environmental, and cultural dimensions of Colombian family farmers. The contours of two research horizons for further research are outlined, they can be briefly described as: (a) explorations of diffusion beyond bottom-up localities involving changes of socio-political structures and (b) the development of conceptual and methodological frameworks for the realisation of bottom-up transformative research alliances.