2025 was among driest years on record for world’s rivers, study finds

Rivers across the world experienced one of their driest years in more than three decades in 2025, a comprehensive study of global water resources has found.

The assessment of the global water cycle by the World Meteorological Organisation (WMO) reveals a depletion in the world’s water savings bank: the amount of freshwater held on or under the ground, including groundwater, lakes, rivers, snow, ice moisture in the soil and inside plants and trees, was 42% below normal across the world last year.

The impacts of the climate crisis on extreme weather and the creation of so-called weather whiplash events are driving a more erratic and unpredictable water cycle. From melting glaciers to extreme droughts and flash flooding, the world’s rivers are swinging between having too much and too little water.

The last seven years have seen the fewest rivers around the world with “normal” flows since 1991. In 2025, one of the warmest years on record, only about a third of rivers were in the normal range, while 36% of the global river basin area had river flows below or well below normal, and 21% were above- and much-above-normal flows, according to the WMO study, using simulations from 13 global hydrological models, driven by observed weather data.

Celeste Saulo, secretary general of the WMO, said: “We are depleting that savings account. Global terrestrial water storage has shown a declining trend since 2014–16 – a persistent, decade-long signal.”

Last year, for the fourth year in a row, each of the world’s 19 major glacial regions lost ice mass. Glaciers have seen their greatest losses of ice mass since the 1990s, and the largest losses are the most recent. In 2025 alone the ice mass loss was 400 gigatons, which adds 1.1mm to global sea levels.

The analysis is a comprehensive, science-based assessment of the entire water cycle loop, including river flows, groundwater, evaporation and transpiration, land water storage, and snow and ice. Wayne Jenkinson, director of hydrology at the WMO, said the research was a call to action in the face of a continuing global picture of declining water resources.

“We need to redouble our efforts to improve our understanding of water resources globally,” he said. “This requires increased data collection and sharing; that is how we increase understanding and protection for people’s lives and wellbeing.”

The study is published as rivers across the world struggle against multiple threats caused by climate crisis-induced droughts, pollution and overexploitation.

And the impact on our river systems has direct knock-on impacts for people, their wellbeing and the global economy.

This summer record-low water levels on the Danube created an unprecedented energy crisis in Hungary and Romania, after all but one of their nuclear reactors had to shut down because the river was too low to provide water to cool them.

The Mississippi River, which is the primary source of water for 50 US municipalities, is threatened by chemical pollution that has created hypoxic dead zones in the Gulf of Mexico, sea level rise that is hastening wetland loss and saltwater intrusion, as well as intermittent droughts. Major African rivers such as the Nile, Niger and Zambezi face significant threats from severe pollution and climate-induced droughts that reduce water levels and harm local ecosystems.

In England not one river is in good overall ecological and chemical health. They are suffering from a toxic combination of sewage pollution, agricultural pollution, the impact of forever chemicals and overabstraction.

The WMO research shows the threat to rivers is continuing and, in some cases, accelerating. In 2025, for the seventh year in a row, the number of river basins with “normal” conditions was in a clear minority: ranging between 34 and 38%, compared with the average of 46% at normal conditions between 1991 and 2020, according to the report.

Across the five years the WMO analysis has taken place, from 2021-25, repeated below-normal river flows were seen in major parts of the Amazon and La Plata basins, North America, central and east Africa, central Asia and the Middle East.

Below-normal to much-below-normal river flows affected much of North America, the La Plata and São Francisco basins of South America, eastern European basins, the Middle East and central Asia.

In each of the past five years, national meteorological and hydrological services around the globe reported record-breaking floods and droughts. Some places have had no recovery time between events.

• Over the next year, in a series called Our Rivers, the Guardian will focus on the environmental challenges facing the world’s rivers, looking at the waterways around the planet that are overengineered or suffocating and drying up, and those that are being opened up again and given new life