Assessing the Impact of Climate Change on Water Resources: The Challenge Posed by a Multitude of Options

Global warming due to anthropogenic emissions of greenhouse gases is already altering the Earth’s climate. A changing climate implies shifts in long-term temperature and precipitation patterns, which in turn will affect the spatiotemporal distribution of water resources. It is imperative to study the impact of climate change on water resources so that adequate adaptation actions can be planned well in advance. We, therefore, need reliable methods to estimate how the timing and magnitude of available fresh water in a region may change in response to a changing climate. This chapter summarizes the main approaches that are used to achieve this goal. We focus on the numerous choices that a modeler faces when attempting to quantify the impact of climate change on water resources of a region. We discuss the relative strengths and weaknesses of each approach. These choices vary from the choice of model structures representing global climate and local hydrology, possible trajectories of greenhouse gas emissions in the future, to methods for model evaluation. Wherever feasible, we provide recommendations that can help a modeler in choosing an appropriate course of action. We conclude the chapter with a discussion on recent techniques developed to deal with large uncertainties in projections of climate change and possible research directions that will benefit the impact assessment community

Theoretical and Methodological Pluralism in Sustainability Science

Sustainability science is an integrative scientific field embracing not only complementary but also contradictory approaches and perspectives for dealing with an array of sustainability challenges.In this chapter we distinguish between pluralism and unification as two main and distinctly different approaches to knowledge integration in sustainability science. To avoid environmental determinism, functionalism, or overly firm reliance on rational choice theory, we have reason to promote pluralism as a way to better tackle sustainability challenges. In particular we emphasise two main benefits of taking a pluralist approach in research: it opens up for collaboration, and ensures a more theoretically informed understanding of society.After a brief introduction to how we interpret the field of sustainability science, we discuss ontology, epistemology and ways of understanding society based on social science theory. We make three contributions. First, we identify important reasons for the incommensurability between the social and natural sciences, and propose remedies for how to overcome some of the difficulties in integrative research. Second, by suggesting a frame that we call ‘social fields and natural systems’ we show how sustainability science will benefit from drawing more profoundly on – and thus more adequately incorporate – a social science understanding of society. As such, the frame is a foundation for pluralism. Third, by suggesting a new theoretical typology, we show how sustainability visions and pathways are associated with particular theoretical and methodological perspectives in geography, political science, and sociology; and how that matters for research and politics addressing sustainability challenges. The typology can be used as a thinking tool to frame and reframe research