The world’s water cycle is becoming increasingly unstable, with growing swings between drought and excessive rainfall, while crucial freshwater reserves continue to diminish, the United Nations warned on Thursday.
The World Meteorological Organization (WMO), in its annual State of Global Water Resources report, said 2025 ranked among the three driest years for the world’s rivers in more than three decades.
The report found that the planet’s overall freshwater storage — including groundwater, rivers, lakes, soil moisture, vegetation, glaciers, ice and snow — has continued a decline lasting about a decade.
WMO Secretary-General Celeste Saulo expressed particular concern about the depletion of slower-replenishing resources such as groundwater and glaciers. These reserves have traditionally acted as the planet’s “savings account”, providing protection when rainfall and river flows decline.
They have provided “a buffer that absorbs bad years so that a single drought or a single dry season does not translate directly into a water crisis”, Saulo told reporters.
Now, she warned, “we are depleting that savings account. We are spending our reserves.”
Glaciers lost significant amounts of ice across every region for a fourth consecutive year in 2025. Between 2023 and 2025, global glaciers shed an estimated 1,400 gigatonnes of water — roughly equivalent to 560 million Olympic-sized swimming pools and about one-third of annual global freshwater withdrawals.
Groundwater is showing similar signs of stress. “Nearly two-thirds of monitored wells worldwide showed conditions outside the historical norm in 2025,” Saulo said.
The WMO also warned that an exceptionally strong El Niño could intensify water-related extremes. The current pattern is expected to become the strongest since comparable records began around four decades ago.
“The strengthening El Nino will increase the risk of drought in some areas, and flooding in others,” Saulo cautioned.
Even before its effects intensified, river flows were already unusually disrupted. Only about 36% of monitored river basins recorded normal flows in 2025, while another 36% experienced below-normal discharge and 21% recorded above-normal conditions. It marked the seventh consecutive year in which basins experiencing normal conditions were in the minority.
The WMO called for stronger international cooperation on water monitoring and early-warning systems, noting that significant data gaps remain, including in some of the areas most vulnerable to water-related disasters.
“Weather respects no borders, and this is especially true for water,” Saulo said, calling for “shared data, shared standards and shared early warnings.”
“A river basin is fed by water upstream, often in another country,” she added, pointing to the recent China-Nepal disaster as an example of how water and glacier-related hazards can cross national boundaries.