When it comes to water, the world confronts an unsustainable situation. But fixing it is not only within reach, it is also the low-hanging fruit in tackling climate change and generating jobs and growth. Year after year, in one region after another, record-high heat waves and droughts are followed by destructive storms and floods. Food systems are running dry and cities are sinking as we reach the limits of extracting water from the land. More than 1,000 children under the age of 5 die each day from illnesses caused by unsafe drinking water and a lack of sanitation, and hundreds of millions of women spend hours each day collecting and hauling water. This is a human-made crisis, and it can and must be resolved through human interventions. The costs will be insignificant compared with the economic and humanitarian harm inflicted by continued inaction. The first step is to recognize that the problems are not merely local. A destabilized water cycle affects every corner of the world. Current approaches deal with the water we can see and assume that supply is stable. But this is no longer true, as changes in land use, climate change, and a water cycle out of kilter are affecting rainfall patterns. The first step is to recognize that the problems are not merely local. A destabilized water cycle affects every corner of the world. Mariana Mazzucato, Ngozi Okonjo-Iweala , Johan Rockström, Tharman Shanmugaratnam Current thinking overlooks the “green water” in our soil, plants, and forests, which is recycled through the atmosphere. Green water generates around half the rainfall that we receive on land, the very source of all our freshwater. In the same vein, countries are connected not only through flows of blue water (like rivers) but, more critically, through atmospheric flows of moisture. As a critical component of the global water cycle, green water urgently needs to be better managed. Most dangerously, disruptions to the water cycle are deeply intertwined with global warming and the decline of the world’s biodiversity, with each reinforcing the other. A stable supply of green water in soil is crucial to sustaining the land-based natural systems that absorb up to 30 percent of the carbon dioxide emitted from fossil-fuel combustion. But deforestation and the loss of wetlands and soil moisture are depleting the planet’s greatest carbon stores, with devastating consequences for the pace of global warming. Rising temperatures then trigger extreme heat waves and increase evaporative demand in the atmosphere, which severely dries landscapes and heightens the risk of wildfires.Insufficient food, accelerated spread of diseases, increased forced migration and cross-border conflicts are just a few of the predictable outcomes. Such a large-scale collective and systemic problem can be fixed only with concerted action across boundaries and cultures. It demands a mission-driven approach to water that cuts across sectors and focuses on all levels, from managing local river basins to shaping multilateral cooperation. We can and must succeed on the world’s most important water missions: launching a new Green Revolution in food systems to cut back on water use while increasing agricultural yields to meet a growing population’s nutritional needs; conserving and restoring the natural habitats that are critical for protecting green water resources; establishing a “circular” water economy in every sector; and ensuring that every vulnerable community has adequate clean and safe water and sanitation services by 2030. These missions require new ways of governing. Policymaking must become more collaborative, accountable, and inclusive of all voices, especially those of youth, women, marginalized communities, and the indigenous peoples on the frontlines of water conservation. The most fundamental policy shift lies in valuing water properly to reflect its scarcity and its critical role in sustaining the natural ecosystems that every society depends on. We must cease the underpricing of water and harmful agricultural subsidies that drive unsustainable usage and degrade the land, channeling those funds into water-saving solutions and support for the poor and vulnerable. Such a large-scale collective and systemic problem can be fixed only with concerted action across boundaries and cultures. Mariana Mazzucato, Ngozi Okonjo-Iweala , Johan Rockström, Tharman Shanmugaratnam To fix chronic underinvestment in water, we must reprioritize water infrastructure in public finance, where it is oddly neglected in most countries. We must ensure larger and more reliable flows of finance to help lower-income countries invest in water resilience. Development banks and finance institutions will need to work closely with governments to support national water missions that reflect local needs and ecological conditions. International trade agreements also offer potential levers to promote efficient water use, because they can ensure that the “virtual water” embedded in traded goods does not aggravate scarcity in water-stressed regions. Just as we do for emissions, we must compile data on corporate water footprints and water-use disclosure. We must also develop systems for valuing water as part of natural capital. Putting a price on this most critical resource could deliver significant dividends. In short, we must shape markets across our economies so that they become radically more efficient, equitable, and sustainable in their water use. The 2023 preliminary report of the Global Commission on the Economics of Water set out the case for pursuing fundamental change in the way the world manages water. Our final report this October will show how we can do so through transformative action. If we do not address these problems head on, wildfires, floods, and other extreme events will only become more intense and deadly. Advancing the water security agenda may seem more difficult amid growing geopolitical tensions, but it presents an opportunity to prove that collaboration can benefit all countries and enable a just and liveable future for all. We cannot shrink from this challenge. The authors co-chair the Global Commission on the Economics of Water. © Project Syndicate.