Report on Water and Climate Change:

Stop Floating, Start Swimming: Water and Climate Change – Interlinkages and Prospects for future Act

Water and climate change are inextricably linked. As rising temperatures spur the hydrological cycle, climate change will affect water availability and quality, as well as hydrological variability and extremes, such as floods and droughts. Actions in the water sector, including water resources management, as well as water supply and sanitation services, will substantially shape the resilience of communities and ecosystems.

This report aims at improving the understanding of complex interrelations between climate change and water, and, based on this understanding, it intends to identify and showcase the most adequate water actions for improving climate resilience and mitigating greenhouse gas emissions. Synthesising state-of-the-art knowledge and research from a physical as well as from a political perspective, the report recommends appropriate action, while referring to good practices and methodologies. Thereby, the report primarily targets water practitioners, decision-makers in the water sector, and the water expert community, aiming to help them better understand how the water sector and water-related activities can specifically contribute to climate mitigation and adaptation goals. However, serving as a comprehensive knowledge base, the report does not solely provide evidence-based information for water actors, but also for climate change experts and practitioners.

Eventually, it is time for the water sector to confidently rely on and promote its own strengths, while taking even more responsibility in shaping the future of climate action. For this reason, the present report encourages water stakeholders to further account for the given realities of international and national climate frameworks and structures, while actively developing pivotal water solutions for their successful implementation. In other words – Stop Floating, Start Swimming!

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Executive Summary

Introduction

Why we need to start swimming…

Climate change impacts throughout the water cycle

Climate change is one of the main global challenges of the twenty-first century. This chapter introduces climate change impacts on the hydrological cycle, as well as indicators commonly used for the quantification of climate change effects on water availability and hydroclimatic extremes.

Critical review of climate impact modelling on water resources

This chapter introduces the modelling of climate change and its associated impacts, including those on the hydrological cycle. Furthermore, it discusses possible sources of (projection) uncertainty and their relevance for the assessment of water resources, availability and hydrological extremes, both, now and in the future.

Climate change impacts on hydrology and water resources: global trends

This chapter reflects on potential temperature and precipitation alterations and associated consequences of their interplay. It shows that some trends - particularly those concerning precipitation - are not easy to determine, resulting in a variance of possible future changes. The chapter continues with a discussion of projected global trends in temperature and precipitation until the end of the century.

Climate change impacts on hydrology and water resources: regional case studies

This chapter focuses on climate change impacts on water resources in six case study basins, namely the Blue Nile, Ganges, Upper Amazon, Upper Niger, Limpopo, and Tagus. These river basins were selected to represent various continents and climate zones, including a set of different projected climate change impacts on water availability, water-related activities, and extremes.

Climate resilience through water – coping with uncertainties

This chapter shows that sustainable water management is essential for climate change adaptation strategies and measures, while often creating additional positive effects and co-benefits in various other sectors. Furthermore, the chapter focuses on methods and concepts by and in the water sector that help to address water management issues, even if significant uncertainties about future conditions prevail.

Mitigation of greenhouse gases through water

The relevance of water for safeguarding climate resilience is undisputed. However, the water sector itself as well as water-related activities in other sectors contribute to climate change by emitting significant amounts of highly potent greenhouse gases. This chapter considers the – often untapped – mitigation potential of water-related activities.

Achieving international climate and development goals through water

This chapter discusses how major international climate change, sustainable development and disaster risk reduction policy processes as well as corresponding institutional frameworks have been dealing with water-related challenges. Thereby, it focuses on institutions and processes related to the international climate change architecture that have originated under the UNFCCC. Eventually, the chapter identifies promising water sector entry points for dealing with global water-climate challenges.

Concluding remarks