The secretary-general of the World Meteorological Organization (WMO) has warned the planet’s water supply is becoming more erratic as extreme weather events become more profound.

Celeste Saulo warned the water cycle has become increasingly erratic and extreme, swinging between deluge and drought.

It came as the organisation launched its State of Global Water Resources report which found only about one-third of the global river basins had “normal” conditions in 2024. The rest were either above or below normal – the sixth consecutive year of clear imbalance.

It added 2024 was the third straight year with widespread glacier loss across all regions. Many small-glacier regions have already reached or are about to pass the so-called peak water point – when a glacier’s melting reaches its maximum annual runoff, after which this decreases due to glacier shrinkage.

The Amazon Basin and other parts of South America, as well as southern Africa were gripped by severe drought in 2024, whilst there were wetter-than-normal conditions in central, western and eastern Africa, parts of Asia and Central Europe, it says.

“Water sustains our societies, powers our economies and anchors our ecosystems. And yet the world’s water resources are under growing pressure and – at the same time – more extreme water-related hazards are having an increasing impact on lives and livelihoods,” said Saulo. “Reliable, science-based information is more important than ever before because we cannot manage what we do not measure.  The WMO’s State of Global Water Resources Report 2024 is part of WMO’s commitment to provide that knowledge,” she said.

The report highlighted the critical need for improved monitoring and data sharing.

“Continued investment and enhanced collaboration in data sharing are vital to close monitoring gaps. Without data, we risk flying blind,”  added Saulo.

The report warned  currently an estimated 3.6 billion people face inadequate access to water at least a month per year and this is expected to increase to more than 5 billion by 2050, according to UN Water, and the world falling far short of Sustainable Development Goal 6 on water and sanitation.

Anomalies of mean river discharge for the year 2024 compared to the period 1991–2020, derived from the modelled river discharge data obtained from an ensemble of 12 GHMS simulations.

The WMO said last year was the hottest year on record and began with an El Niño event which impacted major river basins. It contributed to droughts in northern South America and the Amazon Basin and southern Africa.

It was wetter-than-average in Central and western Africa, the Lake Victoria basin in Africa, Kazakhstan and Southern Russia, Central Europe, Pakistan and Northern India, Southern Iran, and North-Eastern China

In the past six years only about one-third of the global river catchment area had normal discharge conditions compared to the 1991-2020 average. This means that two thirds have too much or too little water – reflecting the increasingly erratic hydrological cycle.