The role of water in climate mitigation is much greater than commonly understood, according to the first-ever summary of current research on the topic. The report 'The essential drop to reach Net-Zero: Unpacking Freshwater's Role in Climate Change Mitigation' shows a new way of thinking about climate change that can lead to more effective solutions.

Malin Gustafsson (Swedish Water House)
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Malin Lundberg Ingemarsson, PhD
Programme Manager,
Swedish Water House
Thérèse Rudebeck
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Thérèse Rudebeck, WaterAid Sweden
Lan Wang Erlandsson, SRC Researcher
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Lan Wang-Erlandsson, Stockholm Resilience Centre

For over two years, SIWI and partner organizations have reviewed available scientific knowledge about the role of water in climate mitigation, including aspects like energy, landscapes, food and wastewater treatment. The pioneering work shows that access to water can be a make-or-break factor in the transforms of for example the food and energy systems. The report also identifies knowledge gaps where more research is needed.

The development of the report has been led by Dr Malin Lundberg Ingemarsson at SIWI but it is a joint effort with the Potsdam Institute for Climate Impact Research (PIK), the Stockholm Resilience Centre (SRC), Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), and the United Nations Development Programme (UNDP).


In this report, we explain how the journey towards climate security requires massive, cross-sectoral efforts in improved management of water. It focuses on 1) climate mitigation measures that require or modify freshwater sources or freshwater-dependent social-ecological systems; 2) climate mitigation options within the water and sanitation sector with up-scaling potential.

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Unpacking Freshwater's Role in Climate Change Mitigation

Climate mitigation cannot be achieved at the pace and scale required unless it is water-wise. The research findings are collated in this summary, together with five key messages for water-wise climate mitigation.

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This introductory chapter outlines the reasoning for the research and why it is critical that water is included in climate mitigation. It also defines the structure of the report and the three main parts of which it is comprised.

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The role of freshwater in climate mitigation: Biophysical interdependencies

This chapter explains how climate mitigation measures both depend on, and impact, freshwater resources and the water cycle.

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Governance context of water-related climate mitigation measures

This chapter provides an overview of the global governance frameworks and national instruments relating to climate change, biodiversity, land, water, and sustainable development. Various financing mechanisms to realise the goals are also covered.

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Mitigation measures in drinking water and sanitation services

This chapter illustrates how reducing both direct and indirect GHG emissions in drinking water and wastewater management presents major opportunities for climate change mitigation, including abstraction, treatment, distribution, and discharge.

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Mitigation measures in freshwater systems

This chapter examines the mitigation potential and risks in freshwater ecosystems, including freshwater peatlands, marshes, swamps, lakes, streams, rivers, and tidal wetlands. They can function as either GHG sources or sinks, dependant on their environmental state and management.

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Mitigation measures in land systems

This chapter examines the mitigation potential and risks in land-based systems, and illustrates how the success of land-based climate mitigation relies substantially on freshwater availability and a functioning water cycle.

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Mitigation measures in energy systems

This chapter examines the water-related climate mitigation potential and risks of low emission energy transition plans, highlighting the need to include an analysis of projected demands, availability, and impacts on freshwater.

Wind turbines in the Gaomei Wetlands, which spans over 300 hectares close to Taichung City, Taiwan. Source: Shutterstock.
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Water risks and win-wins for climate mitigation

This chapter identifies priority water risks that must be evaluated in climate mitigation plans, and the essential areas for investment and action that will benefit both water and climate mitigation, critical for future sustainable development.

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Achieving climate mitigation through integrated and cross-sectoral approaches

This chapter demonstrates that integrated approaches, which account for the interconnections between freshwater and climate mitigation, are necessary to achieve water-wise climate mitigation.

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Concluding remarks: Freshwater - the essential drop to net-zero

Chapter 10 concludes the pivotal importance of building strong, polycentric, and inclusive governance systems, which have the capacity to deliver the integrated solutions required for water-wise climate mitigation.

Glossary          Acronyms

In joint effort with

BMZ logo
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Federal Ministry of Economic Cooperation and Development of Germany (BMZ)
logo of the German Corporation for International Cooperation (GIZ)
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German Corporation for International Cooperation (GIZ)
logo of the Potsdam Institute for Climate Impact Research (PIK)
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The Potsdam Institute for Climate Impact Research (PIK)
SIWI logo 2021 - dark blue circle with light blue wave on top. SIWI written on the right
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Stockholm International Water Institute
1. SRC logo digital version horisontal
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Stockholm Resilience Centre (SRC)
United Nations Development Programme (UNDP)
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United Nations Development Programme (UNDP)