World rivers experience driest year in decades - report

Rivers across the world experienced one of their driest years in more than three decades last year, as scientists warned that some of the planet's most important freshwater reserves are being steadily depleted.

A new assessment by the World Meteorological Organization finds that river flows were below normal across more than a third of the world’s river basin area during 2025.

It was one of the driest years for global river discharge in the past 35 years and continued a pattern of increasingly abnormal river flows.

For the seventh consecutive year, the proportion of river basins experiencing what would be considered normal conditions remained well below the long-term average.

The WMO says the findings are part of a much wider and potentially more serious trend, with the amount of freshwater stored on and beneath the Earth’s land surface declining for around a decade.

Terrestrial water storage includes groundwater, lakes, rivers, soil moisture, vegetation, snow and ice.

The organisation says these slower-moving water reserves have traditionally acted as a type of planetary "savings account", providing a buffer that can help countries withstand individual droughts and unusually dry seasons.

However, WMO Secretary General Celeste Saulo warned that this reserve is now being depleted.

"We are depleting that savings account," she said, pointing to a persistent decline in global terrestrial water storage since around 2014 to 2016.

Groundwater is also showing signs of increasing stress.

Almost two-thirds of monitored wells around the world recorded groundwater conditions outside their historical norm during 2025, with the overall balance shifting further towards water deficits rather than recovery.

Persistent groundwater shortages have been recorded in parts of the Americas, Europe, the Middle East, India, southern Africa and Australia in recent years.

The WMO's State of Global Water Resources report also highlights the continuing rapid loss of the world's glaciers.

Every major glaciated region on Earth experienced a net loss of ice for the fourth consecutive year.

Glaciers lost an estimated 408 billion tonnes of ice during the 2025 hydrological year alone, contributing around 1.1 millimetres to global sea-level rise.

Over the three years from 2023 to 2025, cumulative glacier losses reached around 1,400 billion tonnes.

The amount of fresh water contained in this amount of lost ice is equivalent to roughly 560 million Olympic-sized swimming pools.

The WMO report also underlines the increasingly erratic nature of the global water cycle, with countries experiencing both severe drought and destructive flooding.

Asia and Africa have been particularly badly affected.

Together, the two continents accounted for at least half of all recorded water-related extreme events over the past five years and more than 80% of the associated reported deaths.

In 2025, intense monsoon rainfall and tropical cyclones across South and South-East Asia contributed to as many as 3,600 deaths in affected countries.

Severe drought, meanwhile, affected Eastern Europe, the Mediterranean and Middle East and returned to the Greater Horn of Africa.

The WMO says better monitoring and international sharing of water data will become increasingly important as climate change alters the hydrological cycle.

"Water respects no borders," Ms Saulo said.

"A glacier's retreat in one country reshapes water availability for populations hundreds of kilometres downstream."