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Rains in Kenya, where the United Nations Environment Programme (UNEP) is based, leave large parts of the country a verdant, fertile paradise. When the rains start to shift, as they are now, we see not only major problems with droughts and harvests, but with floods that ravage communities and infrastructure. This is a global pattern, with climate change most often affecting water. It is not just droughts, floods and irregular rainfall, which alter runoff and groundwater levels. We are also seeing changes in evaporation and humidity, as well as snow accumulation and melt.

Food security, human health, urban and rural settlements, energy production, industrial development, economic growth, and thriving ecosystems are all climate and water dependent. This challenge is only going to grow with increasing populations, which will require more food and water, placing further stress on water resources and damaging the environment.

To deal with these growing problems, improving water resources management while maintaining biodiversity and the sustainability of freshwater ecosystems will be crucial.

Managing water in our cities is critical

Balancing the equation is especially important for large cities. With growing urbanization, city water supplies are particularly vulnerable to climate change. By 2050, 685 million people living in over 570 cities will face an additional 10 per cent decline in freshwater availability due to climate change. Some cities¡ªsuch as Amman, Jordan; Cape Town, South Africa; and Melbourne, Australia¡ªmay experience declines of between 30 and 49 per cent. Santiago, Chile, may see a decline of over 50 per cent.¹?We need to be more efficient in water use, be smarter in how we think about and build infrastructure, and protect water sources themselves.

The need for improved water-use efficiency and demand management, leakage control and upgraded water infrastructure are likely to be severe in many cities in coming years. At the same time, increasing variability in rainfall intensity and patterns caused by climate change has a significant impact on urban drainage systems, with an increase in combined stormwater overflows and flooding during heavy precipitation.²

Integrating grey and green infrastructure, and taking an ecosystem-centric approach, can provide valuable solutions to decreasing vulnerability while boosting the resilience of our systems. Measures such as the creation of more urban green space and the construction of wetlands can shield cities from storms and flooding by absorbing excess water and diminishing runoff through infiltration while improving water quality by filtering and absorbing nutrients and other pollutants.

Restoring or constructing wetlands, coastal mangrove forests and natural floodplains are hugely important, nature-based adaptation approaches to water conservation as well as climate change mitigation.

Protecting water sources¡ªboth surface and groundwater¡ªto ensure the sustainability of these ecosystem services will be as important as augmenting storage and water transfer infrastructure to meet increasing demands and to cope with more irregular and infrequent replenishment of urban water supply systems.

Nature-based solutions bring multiple benefits

Restoring or constructing wetlands, coastal mangrove forests and natural floodplains are hugely important, nature-based adaptation approaches to water conservation as well as climate change mitigation. If we reduce the impacts of climate change, we reduce the need for adaptation, as these ecosystems act as carbon sinks, absorbing greenhouse gas emissions.³?Peatlands store at least twice as much carbon as all of Earth¡¯s forests,^4?while mangrove soils hold over 6 billion tonnes of carbon and can sequester up to four times more carbon than their terrestrial counterparts.⁵

Collectively, these approaches are known as nature-based solutions (NBS) for adaptation or mitigation, or ecosystem-based adaptation measures that place people at the centre of interventions, as part of complex systems. These measures are gaining attention and funding, and form a core part of UNEP work in the area of climate.⁶

Currently, UNEP and the Food and Agriculture Organization of the United Nations are supporting the Republic of the Congo and the Democratic Republic of the Congo in the development of a programme to protect and sustainably manage the Cuvette Centrale Peatlands, which is estimated to be the largest continuous tropical peatland complex in the world, covering an area the size of England. It contains the equivalent of two years of global greenhouse gas emissions,⁷?which could be released if the Peatlands were degraded or drained by human interference or prolonged periods of drought.

Embracing adaptation and mitigation measures through water is a win-win-win proposal.

This large freshwater ecosystem also contains unique biodiversity and plays a crucial role in sustaining large downstream populations. Compared with technology-based solutions to climate challenges, nature-based solutions such as wetland conservation and restoration often cost less and have multiple benefits for a variety of sectors and political goals.^8,9?They can thus help meet the infrastructure investment gap, notably in developing countries, in a cost-effective manner. But to scale up nature-based solutions there is a need to ensure long-term access to the land and landscapes for these purposes. In many countries, water and land management fall under different ministries, which can increase competition for the same land and water resources but for different objectives, often leading to suboptimal results and degraded ecosystems. Addressing institutional fragmentation and aligning policies to upscale nature-based solutions can turn this equation around.

Water resources management must be central to climate action plans

Embracing adaptation and mitigation measures through water is a win-win-win proposal. It benefits sustainable water resources management and the human right to safe drinking water and sanitation. It directly addresses the causes and impacts of climate change, including extreme weather events. It also contributes to meeting the Sustainable Development Goals (SDGs), including those on hunger, poverty, health and industry¡ªnot to mention SDG 6, the water goal itself.¹⁰

In 2020, which has been dubbed a ¡®super year¡¯ for nature, countries are reviewing and implementing their nationally determined contributions under the Paris Agreement. We have a unique opportunity to improve and enhance water management practices in ways that will allow communities, countries and basin authorities to make confident, informed decisions that can help to increase climate resilience, improve ecosystem health and reduce the risk of water-related disasters. Advancing the SDG on water¡ªand more specifically the target to govern and manage water resources through an integrated approach (SDG target 6.5)¹¹?¡ªoffers countries significant opportunities to advance their broader development and climate agendas effectively, consistently across sectors and with longer-term viability.¹²

We cannot afford to wait. Climate policymakers must put water at the heart of action plans. The ¹³?campaign underscores that everyone has a role to play. In our daily lives, there are immediate steps we all can take to address climate change and conserve water. We can take short showers instead of baths. We can avoid letting taps run as we wash hands or brush our teeth, and we can install more water-efficient taps and toilets. It is also important to reduce the consumption of water-intensive products and services, such as red meat, electricity and transportation. For example, we know that mayors in many cities can address water loss resulting from inefficient supply and distribution, which is often as high as 50 per cent; focus on protecting and restoring ecosystems that depend on water; and make water available. And when we drive these kinds of efforts, we can make a big difference in the protection of freshwater ecosystems, climate and sustainability challenges, and in the well-being of our societies.

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Notes

¹ C40 Cities, ¡°Restoring the flow¡±, 2020. Available at ?(accessed on 13 March 2020). ?

² Hessam Tavakol-Davani and others, "How does climate change affect combined sewer overflow in a system benefiting from rainwater harvesting systems?", Sustainable Cities and Society, Vol 27 (July 2016), p.p. 430-438. Available at?.

³ UN-Water, "Climate change and water", Policy Brief (Gen¨¨ve, September 2019 version). Available at:?.

⁴ International Union for Conservation of Nature, "Peatlands and climate change", Issues Brief (Gland, November 2017). Available at?).

⁵ Global Mangrove Alliance and others, "Coastal wetlands and mangroves: a natural climate solution pathway to climate change", A joint submission to the Talanoa Dialogue (2018). Available at .

⁶ United Nations Environment Programme, "UNEP, IUCN to launch new € 20m programme on ecosystem-based adaptations", Press release Ecosystems and biodiversity (Nairobi, 21 January 2020).
Available at .

⁷ Greta C. Dargie and others, "Age, extent and carbon storage of the central Congo Basin peatland complex", ?Nature, vol. 2, No. 542 (7639) (2017), pp. 86-90. .

⁸ Sandra Naumann and others, ¡°Nature-based approaches for climate change mitigation and adaptation. The challenges of climate change - partnering with nature¡± (Bonn, German Federal Agency for Nature Conservation, 2014). Available at .

⁹ United Nations World Water Assessment Programme and UN-Water, The United Nations World Water Development Report 2018: Nature-Based Solutions for Water (Paris, UNESCO, 2018). Available at .

¹⁰ United Nations World Water Assessment Programme and UN-Water, The United Nations World Water Development Report 2020: Water and Climate Change (Paris, UNESCO, 2020). Available at .

¹¹ Global Water Partnership, ¡°Accelerating IWRM monitoring and implementation in 60+countries¡±, 11 March 2020. Available at .

¹² Global Water Partnership and Overseas Development Institute, The Untold Story of Water in Climate Adaptation, Part II: 15 Countries Speak, Synthesis Report (Stockholm, Global Water Partnership, 2019). Available at .

¹³ For more information about World Water Day, see Ãå±±½ûµØWater website at .

20 March 2020

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