The summer of 2023 was marked by devastating floods that affected many parts of Europe. In some cities, the floods, caused by intense and prolonged rainfall, disrupted services and posed serious threats to water quality and public health, as they triggered the release of untreated sewage into rivers, lakes and seas.

Such sewage pollution is a stark demonstration of the links between climate change and sanitation systems. With evermore extreme weather events, flooding and other impacts of climate change, it becomes more imperative to ensure that sanitation systems of any kind can be resilient and fulfil their functions in the face of climate change impacts.

How to do so, while ensuring access for all to safe and dignified sanitation services that are resilient to climate change and contribute to reducing greenhouse gas emissions, was extensively discussed at various sessions during World Water Week 2023, held in Stockholm 20–24 August. The theme of this year’s event was “Seeds of Change: Innovative Solutions for a Water-Wise World”, which invited a rethink of how we manage water, and urged consideration of the ideas, innovations and governance systems that are needed in an increasingly unstable and water-scarce world.

Among the many topics discussed during the week, sanitation and climate resilience emerged as one of the most critical and complex issues that require innovation and collaboration from all stakeholders in the water sector. The takeaways: while awareness is rising, more evidence is needed about the causes and effects that link sanitation and climate impacts. And money remains an issue to solving the question of climate-resilient sanitation.

Awareness is rising

The level of interest is high in the linkages between climate change and sanitation, as seen by the number of related sessions at World Water Week. At least 13 sessions focused on climate resilience and sanitation or water, sanitation and health (WASH), excluding several that focused on climate resilience in the context of the wider water sector.

The interest is driven by the increasing awareness that sanitation and climate resilience are interrelated and essential for achieving good public health outcomes as well as other sustainable development objectives. Sanitation systems and services are vulnerable to the impacts of climate change, such as increased frequency and intensity of extreme weather events, rising sea levels, changing precipitation patterns, and higher temperatures. These impacts can affect the functionality, reliability, and sustainability of sanitation infrastructure, as well as the quality and availability of water resources for sanitation purposes.

Sanitation systems and services are not only at risk from climate shifts – they also contribute to greenhouse gas emissions, especially from the storage, treatment and disposal of faecal sludge and wastewater. Recent estimates indicate that the global sanitation sector is responsible for over half a billion metric tons of CO₂ equivalents annually, with almost equal contributions from sewered and non-sewered sanitation systems.

Academia, practitioners and policymakers alike are increasingly interested in these interlinkages. Such intersecting perspectives should provide a good foundation for incorporating considerations about climate change in sanitation planning and implementation, and vice versa.

Missing links for cause and effect

Despite this growing interest, discussions in several sessions at the conference indicated that the evidence on the linkages between sanitation and climate resilience is only just emerging. There is no agreed definition of what climate-resilient sanitation exactly is.

While some frameworks and indicators for assessing climate resilience of sanitation systems are promising, they have not been used and validated widely yet. It remains unclear what and even if indicators can be used comparatively on a global level.

This context requires highlighting the various perspectives of resilience when applied to sanitation systems. Resilience of sanitation infrastructure may not mean the same thing as resilience of sanitation systems: in other words, operating a sanitation system includes management structures, as well as policy, regulatory, financial and other governance issues, beyond the physical infrastructure itself.

Moreover, the relationship between climate-resilient sanitation and other related concepts, such as safely managed sanitation or citywide inclusive sanitation, is not well established or clear. We have yet to see if the concepts are very different or how much they overlap across the sanitation sector.

At the same time, the linkages between climate resilience or adaptation and climate mitigation are also not fully understood in the context of sanitation services and systems. For example, more frequent emptying of pit latrines and septic tanks and quickly transporting any faecal sludge safely to effective treatment facilities can contribute to reducing greenhouse gas emissions from those sanitation technologies, while also ensuring that excreta is transported away from households and hence reducing risks for the spread of pathogens during flooding events. However, the effects of such interventions – let alone their magnitude – are yet to be confirmed and documented in the scientific literature. These gaps are important to highlight: actionable data are needed on which interventions can be based to implement climate-resilient sanitation.

Following the money

A study from the World Bank previously estimated that about USD 114 billion is needed annually to finance the costs of achieving SDG 6.1 and 6.2. Current levels of financing, however, fall far below that mark.

This is why the estimated USD 803 billion of climate finance available from public and private sources globally is of keen interest to those in the sanitation sector. The possibility of accessing climate finance for plugging the financing gaps for SDG 6.2 is a key driver for the interest in sanitation-climate linkages.

However, previous SEI research has indicated that the sanitation sector is a recipient of only a tiny fraction of available global climate finance, whether from public or private sources. Most of this financing has gone to projects on large-scale wastewater treatment and reuse, several examples of which were shared at World Water Week, particularly from the Arab region. There are recent developments to attract financing from the voluntary carbon credit markets for container-based sanitation initiatives, but these are still nascent and yet to be replicated globally.

Several challenges block access to climate finance for sanitation. These include the lack of clear methodologies for quantifying the benefits of sanitation interventions for climate mitigation and adaptation, the high transaction costs and complexity of applying for climate funds, the limited capacity and awareness of sanitation actors to access climate finance, and the competition with other sectors and priorities for limited resources.

These challenges need to be overcome so that we see more examples of sanitation initiatives or projects accessing climate finance with time. Generating more evidence about how sanitation interventions can promote climate resilience and raising awareness about these linkages will contribute towards tackling finance challenges and other barriers to bringing these issues to the fore.

Encouragingly, some collaboratives that are working at the intersection of climate change and sanitation were described at the conference, for example, the ongoing work to develop and include climate resilience indicators in the Joint Monitoring Programme for Water Supply, Sanitation and Hygiene, as well as the growing Climate Resilient Sanitation coalition. More countries are also including sanitation in their climate reporting and planning for nationally determined contributions, or NDCs. Overall, these steps forward show that awareness is rising, which could lead to uncovering the missing links between cause and effect, eventually unlocking access to financing for climate-resilient sanitation.