WMO Report Confirms Decade-Long Decline in Global Freshwater Storage, Citing 2025 as One of Driest Years for River Flows

In 2025, rivers worldwide experienced one of their driest years in more than three decades, marking a continuation of a decade-long decline in the Earth's terrestrial water storage. The World Meteorological Organization (WMO) confirmed the trend in its State of Global Water Resources 2025 report, revealing that 36 percent of the world's river basin areas saw below-normal discharge.[1][2]

Terrestrial water storage—which encompasses groundwater, soil moisture, lakes, rivers, and ice—has been steadily decreasing since 2014. WMO Secretary-General Celeste Saulo described these slow-responding reserves as the planet's "savings account," designed to absorb the shock of occasional dry seasons. "One of the central stories of the 2025 report is what is happening to that savings account. And the simple answer is that we are depleting it," Saulo stated during the report's launch in Geneva.[2]

The past seven years have seen the fewest rivers maintaining "normal" flows since 1991. According to the WMO, the number of river basins operating under normal conditions ranged between 34 percent and 38 percent in 2025, a stark contrast to the 46 percent average recorded between 1991 and 2020.[2]

The cryosphere is reflecting the same deficit. For the fourth consecutive year, every major glaciated region on Earth lost ice mass. Between 2023 and 2025, global glaciers shed approximately 1,400 gigatons of water. This volume is roughly equivalent to one-third of total annual freshwater withdrawals worldwide, or enough to fill 560 million Olympic-sized swimming pools.

Groundwater levels mirror the surface-level drying. In 2025, nearly two-thirds of monitored wells globally recorded conditions outside their historical norms. Rather than recovering, the balance of these subterranean reserves shifted further toward deficit compared to 2024. Persistent groundwater deficits were tracked across Central and Eastern Europe, the central United States, and parts of South America and Australia.

The WMO's findings were synthesized using data from 13 global hydrological models, including the Copernicus Emergency Management Service's Global Flood Awareness System (GloFAS). By integrating these models with satellite records and national observations, researchers mapped out regions where physical hydrological monitoring remains sparse or unavailable.

The data illustrates an increasingly erratic water cycle swinging between severe scarcity and extreme deluge. While regions like the Amazon basin and North America faced recurring deficits, parts of South and South-East Asia experienced above-normal river flows. The human cost of this volatility is heavily concentrated: over the past five years, Asia and Africa accounted for at least half of all recorded water-related extreme events and more than 80 percent of the associated fatalities.[3]

Moving forward, the strengthening of the El Niño weather pattern is expected to further amplify these extremes. Hydrologists and policymakers are now tasked with managing water systems that can no longer rely on the predictable, historical baselines of the past century, requiring a shift toward more resilient infrastructure and cross-border water management.[3]