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Water for climate action [1]

['Jon Lane', 'Stockholm International Water Institute', 'Stockholm']

Date: 2026-05 

Citation: Lane J (2026) Water for climate action. PLOS Water 5(2): e0000517. https://doi.org/10.1371/journal.pwat.0000517 Editor: Guillaume Wright, PLOS: Public Library of Science, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND Published: February 9, 2026 Copyright: © 2026 Jon Lane. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The authors received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist.

The need for climate action The science on global heating is unequivocal. At the current rate of emissions, the carbon budget for 1.5°C will soon be exhausted. Geopolitical challenges and existing multilateral efforts cannot be solely relied upon. Water professionals can be a significant part of a growing global people’s movement, vividly described by the musician Brian Eno in The Economist in 2022 [1].

Water’s contribution to climate action Historically, water professionals have been well aware that water is the medium through which global heating impacts human civilisation and the planet’s ecosystems. An average global temperature rise of a degree or two – innocuous to a lay person at first glance – has a huge impact on the functioning of the global climate and hydrological cycle both in the atmosphere and in the oceans. That impact is manifested in storms, floods, droughts, glacier melting, ocean heatwaves, coral bleaching and many other meteorological changes. Water professionals work hard to adapt water management systems to those changes and increase their resilience. There is plentiful research and policy documentation about water for adaptation and resilience, including those published by leading sector entities such as the Alliance for Global Water Adaptation or the International Water Management Institute. However, while that work is important, it addresses the symptoms of global heating not the causes. Regarding mitigation, which directly addresses the cause of global heating, the water community has increasingly become aware that poor water management contributes significantly to greenhouse gas emissions. Three successive documents summarise the collective knowledge about water for mitigation: Stop Swimming, Start Floating published by GIZ in 2021 [2], The Essential Drop to Reach Net-Zero published by SIWI in 2022 [3], and UN-Water’s Analytical Brief on Water for Climate Mitigation published in 2024 [4]. While there are few precise figures from published research on this topic, latest estimates by Lamb et al [5] and by Our World in Data [6] suggest that approximately 6–8% of global greenhouse gas emissions are water-related. If water were a country, it would be the fourth-biggest emitter in the world. Water is key to climate, and vice versa. Both are integral to both planetary and human health, study areas that are increasingly important for World Water Week and its host institution, the Stockholm International Water Institute (SIWI).

The theme and outcomes of World Water Week 2025 From its foundation in 1991, World Water Week has been a meeting of water people; it has since evolved into a meeting about water for all people, to whom SIWI offers water as a tool to achieve their goals. To provide a coherent intellectual framework for the conference, SIWI selects a different theme each year. The mathematician Richard Hamming famously asked his colleagues what the important problems in their field were, what problems they were working on, and if their work was not important, why they were doing it. On that compelling logic, SIWI recognised that climate change is the most important issue humanity has ever faced and dedicated World Water Week 2025 specifically to water for climate action. Session hosts and participants were urged not only to discuss water and climate in general but to present actions for both mitigation and adaptation. SIWI gave particular prominence to water for mitigation because there are very few organisations (for example the Water Initiative for Net Zero, the Water Pavilion team at successive UNFCCC COPs, UN-Water) studying or promoting it. The discussions at many sessions during the Week demonstrated that the water community is indeed acting energetically on water resilience and adaptation. While fewer sessions were dedicated to water for mitigation, participants began to identify and share scientific evidence of achievements. From those presentations and from the data in the SIWI and UN-Water documents, the water actions that can make the biggest contributions to climate change mitigation are: Irrigating rice fields by alternate wetting and drying, instead of flooding, to reduce the methane emitted by the rice plants while increasing their yield.

Keeping aquatic ecosystems, notably peatlands, wet to help them sequester carbon and prevent them emitting methane.

Capturing methane from sanitation and wastewater treatment systems and using it to generate electricity.

More effectively managing hydroelectric and other dams to reduce their methane emissions.

Reducing energy usage in water utilities, to reduce power demand and in turn their greenhouse gas emissions.

Helping wetlands, forests, and rivers store carbon and buffer communities from climate shocks. A striking feature of this list is that most of these actions reduce methane, a potent greenhouse gas. Global heating can be decelerated proportionately more by reducing methane emissions than those of carbon dioxide. The World Bank’s online publication “Bending the Curve: A Triple-Win Blueprint for Global Methane Reduction” [7] explains this topic comprehensively, mentions rice production prominently, and touches on wastewater treatment.

The SIWI Seminars at World Water Week 2025 Among several hundred sessions during the Week, the series of seven SIWI Seminars was designed to cover most aspects of water for climate action. 14 of the 21 sessions making up the Seminars were recorded and made freely available online [8]. Their contents were summarised in various documents, including in this set of PLOS Water articles. These five articles all originated from discussions at those Seminars. They are intended to call our collective attention to particular aspects of water for climate action, with an emphasis on innovative and progressive work. Hedke et al. [9] argue that climate change is a force-multiplier, exacerbating challenges in water and health. They reflect the collective thinking emerging from global discussions on integrated responses to climate and health challenges, with water as the mediator. They emphasise the need for cross-sectoral coordination and systems thinking to effectively address complex, interlinked challenges: working jointly; training professionals to work in all three domains; shifting from response to preparedness; putting justice and knowledge at the centre; and measuring and managing shared risks. Lefore and Schmitter [10] highlight the trade-offs between efforts to achieve goals on climate adaptation, climate mitigation and water security in food systems. Farmers are under pressure to adapt to climate change to improve global food security and simultaneously expected to mitigate emissions to manage climate change. Achieving food and water security requires robust data; evidence systems are required to measure and protect water security in food systems amid climate-related investments. Rimšaité [11] also addresses agriculture, specifically how water governance can be strengthened to support more resilient agricultural systems. Three case studies indicate that water governance strategies need to be effective at the local level including via adaptive regulatory frameworks and inclusive stakeholder engagement; that water governance frameworks must be practical and build trust with farmers in order for initiatives to be successfully scaled; and that current efforts in food production are more advanced in adaptation than in mitigation. Vesnovskii and Larshans [12] highlight the cross-cutting role of water across multiple planetary boundaries, noting how far the limits of freshwater use have been pushed. They propose that transformative approaches rather than incremental improvements are needed. They provide concrete recommendations for aligning water governance with climate adaptation and mitigation, biodiversity protection, and pollution control, while also pointing to emerging opportunities for innovation and investment. They argue that water has long ceased to be a sectoral issue – it is the foundation of planetary stability and human well-being. Jones-Crank et al. [13] argue for improvements in global water and climate multilateral conferences, such as the UN FCCC Conference of Parties (COP) annual meetings and the UN Conferences on Water. They propose increased integration between water and climate, and accountability mechanisms for these conferences to ensure that commitments are put into practice. Their key recommendations for further integration and accountability include: to track the outcomes from multilateral conferences on water and climate; to hold cross-sectoral preparatory meetings before major conferences; and to address disinformation and misinformation. The five articles, while covering different technical aspects of water management as mentioned briefly above, all deal with water governance, the roles of multilateral organisations, and the need for cross-sectoral approaches. These themes are aligned with those emerging more generally during World Water Week. The key messages about water for climate action from the whole SIWI Seminar series have been published online by SIWI [14]. Those include the important water actions for climate mitigation which have been listed above in this paper, together with many other messages grouped under the headings of: ethics and policies; governance and regulation; collaboration; planning and implementing work; science, technology and tools. SIWI intends that any organisation or person working on water and climate can find actions relevant to them in this list. Presentations on water for mitigation in other sessions at World Water Week – whether hosted by SIWI or by other organisations – were recorded and are freely available on World Water Week’s YouTube channel. Here are two examples. Professor Barbara Evans of Leeds University, a co-author of a seminal study of greenhouse gas emissions from sanitation systems in Kampala [15], spoke on this topic at the SIWI Seminar on Sanitation and Mitigation (session no. 14013). She emphasised that humans will excrete forever so as other greenhouse gas emissions are reduced, those from human excreta will become a larger percentage of the total. A win-win is that the measures to reduce emissions from sanitation systems are the very same measures that improve the service provision and health benefits of the sanitation systems. Hiz Jamali of the Asian Development Bank spoke about emissions from rice production in the Decarbonising Asia’s Water session (session no. 12148). He noted that rice paddies contribute 12% of global methane emissions, that demand for low-carbon rice is rising, and presented his latest research indicating that alternate wetting and drying reduces methane emissions by 27–67% while increasing rice yields by 15–30%.

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[1] Url: https://journals.plos.org/water/article?id=10.1371/journal.pwat.0000517

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