The global water cycle is our planet's life-support system. It is a powerful environmental pump, with forests transpiring moisture and replenishing giant atmospheric rivers of freshwater. It is also a global thermostat, regulating the climate through evaporation and cloud formation. And it is a giant filter, purifying water as it percolates through the soils and wetlands.
But while all life depends on the water cycle, it is coming under increasing strain and losing its ability to perform these essential functions, leading the United Nations to declare a new era of "global water bankruptcy". Rising temperatures, ecosystem degradation, and shifting rainfall patterns are weakening the natural systems that regulate water flows and quality, while conventional infrastructure, designed for historical hydrological conditions, is increasingly exposed to variability, sedimentation, and shock.
To protect the water cycle from these competing pressures, we must embrace a holistic perspective. That means treating the cycle as shared infrastructure, and reshaping investments and governance accordingly.
