Climate change is pushing already overstretched water supplies to the limit. Cape Town’s residents are currently enduring a devastating drought; the 2015 drought in São Paolo forced 9 million Brazilians to ration water. Around the world, one in four of the biggest cities is suffering from water stress.

In fact, water scarcity already affects more than 40% of the global population. According to the UN, our dwindling water resources are increasingly contaminated by pollutants from intensive agriculture, industrial production, mining, urban runoff and wastewater. Meanwhile, our water needs continue to grow, projected to rise by 30% by 2030.

Given the bleak and urgent context, it is not surprising that the global community is looking to nature-based solutions to the water crisis. Healthy forests, wetlands, rivers and other natural systems have always played a fundamental role in providing us with water, and conserving them helps sustain clean water supplies. In Quito, Ecuador, about 80% of the city’s 1.5 million residents receive drinking water from two protected areas in the Andes.

The essential role of nature-based solutions is also incorporated into international agreements and declarations, such as the declaration for water management signed at the 2017 UN climate change conference (COP23), which drew on IUCN’s definition and work in this area. ‘Natural water infrastructure’ is key to our food and water security and our health, which is why the 2030 Agenda for Sustainable Development recognises the importance of nature-based solutions to water challenges.

IUCN pioneered nature-based solutions over a decade ago and continues to implement them widely on the ground. Our WISE-UP to Climate programme enables investment into healthy natural systems such as wetlands and watersheds, which help protect communities from the effects of climate change.

In Kenya, the WISE-UP programme demonstrated how healthy watersheds directly support livelihoods for hundreds of thousands of people in the Tana River Basin, bringing benefits worth more than US$ 170 million a year to local communities. IUCN projects around the world help restore degraded watersheds, such as that of the Miyun Watershed and the Upper Dongjiang River in China, which aims to provide water to 40 million people.

The water crisis is global in scope, but it hits women and the world’s poor hardest, as the lack of sufficient, clean, affordable water impacts health and wellbeing. UNICEF estimates that women and girls spend 200 million hours every day collecting water. IUCN is working to give women more control over the management of this precious resource. Our Building River Dialogues and Governance (BRIDGE) initiative ensures that women actively participate in councils tasked with improving the management of transboundary river and lake basins.

Yet we continue to degrade the ecosystems we so heavily rely on for our water supplies. Wetlands, such as marshes, floodplains and swamps, are nature’s water filters, helping provide clean drinking water. They also protect communities from storms and other extreme weather events, store large amounts of carbon, and provide food and income from fishing. Despite these obvious benefits, we humans have drained almost two-thirds of the world’s wetlands since 1900.

We must use the momentum behind nature-based solutions, which we are seeing at the ongoing World Water Forum and elsewhere, in our efforts to provide safe water to all. This means enacting laws to conserve protected areas. It means generating funds to preserve and restore watersheds. It means conducting further research into how natural systems can best be combined with built infrastructure.

And, in the case of São Paulo, it means protecting existing forests. The critical water shortages which the city experienced in 2015 could return, if logging in the Amazon continues. In Brazil and around the world, we must strive to fully use nature’s potential as we face a mounting global water crisis.