Open Access

This thesis deals with the influence of sustainability communication on the purchase decision of sustainable tourism products involving German specialist tour operators. Sustainability communication is a challenge, because sustainable tourism is an abstract and vague concept which consumers find it difficult to grasp and about which they are sceptical, and the service characteristics of tourism products complicate the decision making stage, which is a high-involvement situation of uncertainty to which sustainable product attributes add complexity. As an introduction, an interdisciplinary theory discussion reveals knowledge gaps in terms of the value-belief-norm theory and the elaboration likelihood model (ELM). The first article, which is the first systematic literature review on the topic, reveals that there is a limited theoretical understanding of sustainability communication, a lack of practical understanding of how to design sustainability messages, and an inadequate set of methodologies for its research. It identifies knowledge gaps concerning: the holistic approach to sustainability communication; its role in the attitude-behaviour gap; an interdisciplinary theoretical understanding focusing on belief-based social psychological theories and theories of persuasion; qualitative methods; and experimental design. The second article investigates the role of sustainability communication in the attitude-behaviour gap, employing the value-belief-norm theory to explain how information is processed by special interest customers. Interview findings show that ineffective sustainability communication is the reason for the gap and that customers unintentionally booked sustainably. The study identifies eight groups of beliefs which explain the processing of sustainability attributes. Sustainability information is effective when it is value-congruent, that is, when customers perceive they can make a difference, they begin to ascribe a responsibility to themselves. The third article investigates how to design an effective sustainability message in tour operator advertising. Drawing on the ELM, the study shows that appeal type does not significantly influence persuasion but the topic presented is important. Cultural sustainability is the sustainability topic that is most persuasive for cultural tourists, while consumer prior knowledge and issue-involvement with the topic promote successful information processing. The thesis has contributed to a target-group specific understanding of effective sustainability product communication and contributes to knowledge in terms of theory, methodology, and practical solutions.

Nowadays, our (western-world) society is characterized by digitalization. This is realized by information and communication technologies, consuming a huge amount of energy. The fact that digitalization comes along with a lot of negative effects onto the environment is slightly known in the case of energy consumption by hardware, especially regarding mobile devices, having a limited battery life. However, awareness of environmental issues of software, being the driver of hardware, is mainly missing, even if the research field addressing corresponding issues is growing. Thus, the doctoral thesis at hand addresses the question How to draw (a) developers and (b) usersattention to environmental issues of software? By presenting (a) a calculation method of the carbon footprint of software projects and (b) a concept for an eco-label for software products, evaluated by a user survey, the doctoral thesis provides two strategies how to draw the attention to environmental issues of software. Summarizing, this thesis can act as a basis for further research in bridging from science to society in the context of environmental issues of software. Its findings can be seen as starting points for practical implementations of methods and tools supporting a more environmentally friendly way of developing software and informing about environmental issues of software usage. In order to get the implementation of the research results of the thesis going, it highlights practical implications for diverse groups of stakeholders - researchers, certifiers, public administration and professional purchasers, and environmental associations - that have been identified as being important for the practical implementation of the presented concepts and, thus, represent the target group of the doctoral thesis.

The dissertation project focuses on empirically investigating consumers´ attitudes, motiva-tions and purchasing decisions regarding sustainable products. The focus on this micro per-spective, however, does not reflect consumers´ roles within the transformation towards sus-tainable consumption. Therefore, the present framework paper puts the included papers into a greater context and evaluates the findings on a meta-level by applying an enhanced transition management theory. The analysis underlines that consumers´ limited personal capabilities are an underlying reason for unsustainable practices. Therefore, the active engagement not only of consumers, but also of companies is required if the transformation is to be successful. If companies actively support consumers in making sustainable choices, consumers can engage in sustainable consumption with only low cognitive efforts. On this basis, genuine sustainable choices are enabled. The dissertation provides practical implications by highlighting potential measures which will help to promote sustainable products from niches to mainstream. In sum, the dissertation project enhances academic understanding of consumers´ sustainable purchas-ing behavior and reveals the potential of integrating such insights into the management of transformations towards sustainable consumption.

Sustainability aims at justice in a threefold sense: intragenerational justice, intergenerational justice, and justice towards nature. However, the justification, specific content and practical implications of justice claims and obligations in the sustainability context often remain underspecified. This dissertation therefore asks: How can the concept of justice be structured systematically? How can justice be specified in the context of sustainability? Which specific problems of justice arise in sustainability policy? And what are the respective contributions of (sustainability) economics and (sustainability) ethics? The five papers of this cumulative dissertation approach these issues from different angles, working at the conceptual level and at the level of cases from biodiversity and fishery policy. In Paper 1, a formal conceptual structure of justice is developed, which lists the conceptual elements of justice conceptions: the community of justice including claim holders and claim addressees, their claims (and corresponding obligations), the judicandum (that which is to be judged as just or unjust), the informational base for the assessment, the principles of justice, and on a more practical level, the instruments of justice. By specifying these conceptual elements of justice, it is possible to analyse and compare different conceptions of justice. In Paper 2, the normative dimension of sustainability is discussed in terms of justice. Based on the identification of certain core characteristics of the concept of sustainability, we determine the specific challenges of justice in the context of sustainability along the conceptual structure of justice (from Paper 1). Inter alia, we show that sustainability calls for the integration of justice claims in the relationships with contemporaries, future humans and nature in a non-ideal context characterized by uncertainty, systemic mediation and limits. Paper 3 addresses the contribution of economics to the assessment of trade-offs between intergenerational and intragenerational justice. Economic analysis can delineate the opportunity set of politics with respect to the two justice objectives and identify the opportunity cost of attaining one justice to a higher degree. While the two justices are primary normative objectives, the criterion of efficiency - when directed at the attainment of these justice objectives - has the status of a secondary normative objective. Paper 4 constitutes a case study, reconstructing the ´biopiracy´ debate from a justice perspective. The paper links to the so called Access and Benefit-Sharing framework of the Convention on Biological Diversity, and addresses the question, which problems of justice arise regarding the utilization of genetic resources and traditional knowledge, especially if associated with patenting. It is shown that the predominant perspective of justice-in-exchange is insufficient and therefore complementary conceptions, namely of distributive justice, corrective justice and structural justice have to be taken into account. Paper 5 empirically assesses the justice notions of stakeholders in the Newfoundland fishery, building on qualitative semi-structured interviews and a combination of inductive and deductive coding. A central result is that inshore fishers are seen as the main claim holders, with a claim to participate and being listened to, and the opportunity to make a living from the fishery. Recognition, participation and distribution are all important domains of justice in the context of the Newfoundland fishery. The paper also discusses the relationship between normative theorizing and empirical justice research. Overall, this thesis integrates ideal and non-ideal normative theorizing, economic analysis, empirical justice research and hints at institutional implementation in the debate on sustainability and justice.

This dissertation concerns the question of how economics can contribute to the analysis of trade-offs between values (or normative objectives). The analysis is illustrated for the case of policies that pursue the goal of sustainability. Methodologically, this is done by reflecting economic concepts in light of philosophical theories and using generic models to analyze trade-offs between particular values. In sum, the work shows how economics can help in analyzing the factual relationships between values by clarifying the set of feasible acts and outcomes. The first paper of this cumulative dissertation concerns the question what a general definition of efficiency with respect to normative objective implies about relationships between two values. In order to conceptualize relationships between values carefully, the analysis distinguishes instrumental from intrinsic values and discusses the question whether there is one intrinsic value (value monism) or many intrinsic values (value pluralism). Next, a small economic model is used to show that there can be different relationships between values such as win-win relationships and trade-offs in value-efficient states if there are three or more values. Further, the distinction between Pareto-efficiency (based on individual preferences) and value-efficiency (which can also include non-preference values) is used to study relationships between values. The second paper uses the definition of sustainability as inter- and intragenerational justice to discuss the relationship between these two objectives. The general aim of this paper is to discuss what economic concepts can contribute to the discussion of tradeoffs between justices. For this, a syntax of the concept of justice is employed, different relationships between justices are defined and economic concepts such as scarcity, efficiency and opportunity costs are transferred to the justice context. One result from this analysis is that there must be a trade-off between these two justices in such respective efficient outcomes. The third paper concerns an intertemporal mechanism leading to the well-known equity-efficiency trade-off in an intergenerational setting. For this, two central characteristics of intergenerational policy making are taken into account: irreversibility and ignorance (or unawareness). A pertinent example is the irreversible use of fossil fuels before and after the discovery of the effect of CO2 emissions on climate change. The trade-off between Pareto-efficiency and intergenerational equity that results from these two characteristics is shown in a model with two non-overlapping generations which use a non-renewable resource. In the model there is initial unawareness about an intergenerational externality from resource use that is only discovered after the irreversible use of the resource. A central result of the paper is the trade-off between intergenerational equity and efficiency that emerges if initially unknown sustainability problems arise after irreversible policies have been enacted. The fourth paper concerns the question what the concept of merit goods can contribute to discussions of sustainability. For this, the history of the concept is discussed, then merit goods are defined and connected to the philosophical literature on different conceptions of well-being. In the next step different challenges and opportunities of merit good arguments are discussed for the sustainability context. For example, it becomes clear that merit good arguments concern conceptions of well-being and do not directly concern the aspect of intergenerational distribution in sustainability problems.

Strong sustainability, according to the common definition, requires that different natural and economic capital stocks have to be maintained as physical quantities separately. Yet, in a world of uncertainty this cannot be guaranteed. To therefore define strong sustainability under uncertainty in an operational manner, we propose to use the concept of viability. Viability means that the different components and functions of a dynamic, stochastic system at any time remain in a domain where the future existence of these components and functions is guaranteed with sufficiently high probability. We develop a unifying and general ecological-economic concept of viability that encompasses the traditional ecological and economic notions of viability as special cases. It provides an operational criterion of strong sustainability under conditions of uncertainty. We illustrate this concept and demonstrate its usefulness by applying it to livestock grazing management in semi-arid rangelands.