Global Water Cycle Is Becoming More Unpredictable, WMO Warns
The global water cycle is becoming increasingly difficult to predict, with rivers, groundwater and glaciers showing signs of growing disruption, according to a new report from the World Meteorological Organization (WMO). The findings show that 2025 was one of the driest years for river flows in more than three decades, while freshwater stored on land continued its long-term decline.
The changes are not limited to areas experiencing drought. Some regions are facing severe flooding at the same time, highlighting how the global water cycle is increasingly shifting between too little and too much water.
Rivers Had One of Their Driest Years
WMO’s State of Global Water Resources 2025 report found that river discharge in 2025 was among the lowest recorded in 35 years. Below-normal river flows affected more than 36% of global river basin areas.
For the seventh consecutive year, only a minority of river basins recorded what the organization considers normal conditions. Between 2021 and 2025, several regions repeatedly experienced below-normal river discharge, including parts of North America, South America, the Middle East, Central Asia and Africa.
At the same time, other areas experienced unusually high water levels and flooding. This contrast shows why changes in the water cycle are not simply a matter of the world running out of water. Instead, the timing, location and availability of freshwater are becoming less predictable.
Groundwater Reserves Are Also Under Pressure
Groundwater provides an important backup when rivers and rainfall cannot meet demand. However, the latest findings show that these underground reserves are also under stress.
Persistent groundwater deficits were recorded in parts of the Americas, Europe, the Middle East, India, southern Africa and Australia between 2022 and 2025. WMO also reported that nearly two-thirds of monitored wells worldwide had water levels outside their historical range in 2025.
Unlike rainfall and river flows, groundwater can take much longer to recover. Continued declines could therefore make communities more vulnerable during prolonged dry periods.
Glaciers Continue to Lose Ice
Glaciers are another important part of the world’s freshwater system, particularly for communities that depend on seasonal meltwater.
The report found that 2025 marked the fourth consecutive year of widespread glacier mass loss across all major glaciated regions. Between 2023 and 2025, glaciers lost an estimated 1,400 gigatonnes of water in total.
Glacier melt can temporarily increase river flows, but continued ice loss eventually reduces the amount of water available during warmer months. Some smaller-glacier regions may already have passed what scientists call “peak water,” when meltwater runoff reaches its maximum before beginning to decline.
Floods and Droughts Are Happening Together
The WMO report also highlights the growing impact of water-related disasters. Asia and Africa accounted for at least half of recorded water-related extreme events and more than 80% of associated deaths over the past five years.
The organization says the strengthening El Niño could further increase the risk of drought in some areas while raising flood risks elsewhere.
Why the Water Cycle Matters
The latest findings suggest that freshwater challenges are becoming more complicated. Rivers can fall below normal levels while intense rainfall causes flooding elsewhere, and long-term reserves such as groundwater and glaciers continue to decline.
The WMO says better water monitoring, shared data and stronger early-warning systems will be increasingly important as countries prepare for more variable water conditions.
