Water cycle is becoming more erratic, WMO warns

The world's water cycle is becoming more erratic, swinging between too little and too much water as freshwater reserves decline, the World Meteorological Organization warned in its annual State of Global Water Resources report.

The UN weather agency said 2025 was among the three driest years for rivers in 35 years, with normal river-flow conditions recorded in only about 36 percent of basins. It said an equal share had below-normal discharge and 21 percent were above normal.

The report said global freshwater storage, including groundwater, lakes, rivers, soil moisture, vegetation, ice and snow, continued a decade-long decline. It found that glaciers shrank across all regions in 2025, the fourth consecutive year of significant global ice-mass loss.

WMO estimated that glaciers lost a cumulative 1,400 gigatonnes of water between 2023 and 2025. It said that was roughly equal to 560 million Olympic-sized swimming pools, or about a third of the world's annual freshwater withdrawals.

WMO Secretary-General Celeste Saulo said groundwater and glaciers had acted as slow reserves that helped buffer drought years, but warned: "We are spending our reserves."

Saulo also said nearly two-thirds of monitored wells worldwide showed conditions outside the historical norm in 2025. She said the strengthening El Nino pattern was expected to increase the risk of drought in some areas and flooding in others.

WMO said better shared water data, standards and early warnings are needed, especially because river basins and glacier risks often cross borders.