As the twin threats of climate change and biodiversity loss come to a head this decade, the fate of our fresh water lies in the balance. Extreme weather is becoming increasingly common, bringing massive rainfall and flooding in some regions and widespread heat and drought in others, with disastrous impacts on both humans and nature. At the same time, we have lost nearly a third of the world’s freshwater ecosystems and 83% of monitored freshwater species since 1970, a rate that is significantly higher than that of terrestrial and marine species in the same timeframe. Freshwater ecosystems deliver the water on which all life depends. The urgency to better protect them is now.