By Abbas Nazil
Climate change is disrupting the global water cycle, reducing freshwater reserves and intensifying floods and droughts, according to the World Meteorological Organization’s latest assessment of global water resources.
The report indicates that freshwater stored in rivers, lakes, groundwater, glaciers, snow and soils declined across significant parts of the world in 2025, with water supplies below historical levels across 42 per cent of the planet’s land area.
The WMO said the changes were making the global water cycle increasingly unpredictable, with communities facing growing risks from water shortages, extreme flooding and the loss of natural water reserves.
According to the assessment, 2025 was among the driest years for the world’s rivers in the past 35 years, while abnormal changes in river flows have now persisted for seven consecutive years.
The largest departures from historical river-flow patterns were recorded across substantial areas of North and South America, Eastern Europe, the Middle East and Central Asia.
The report also found significant changes in groundwater, with deviations from historical levels recorded in about two-thirds of monitored wells.
Compared with 2024, the proportion of areas experiencing groundwater shortages increased, adding further pressure to freshwater supplies in affected regions.
The WMO assessment linked the growing instability of the water cycle to climate change, noting that changes were occurring simultaneously across rivers, groundwater, glaciers and precipitation patterns.
It said the evidence showed that freshwater availability on land was declining globally, threatening the reliability of water resources upon which communities, ecosystems and economies depend.
The report further highlighted accelerating losses from glaciers, which experienced significant water losses across all monitored glacier regions in 2025 for the fourth consecutive year.
Between 2023 and 2025, glaciers lost a volume of water equivalent to about 560 million Olympic-sized swimming pools.
The continued loss of glacier ice presents multiple risks, including increased flooding, rising sea levels and worsening water availability for populations that depend on glaciers and seasonal snow as freshwater sources.
Glaciers, snow and ice normally function as natural reservoirs by storing water for extended periods and releasing it gradually during drier seasons.
The WMO warned that the depletion of these slow-moving water reserves was reducing an important natural buffer against drought, dry seasons and other climate-related pressures.
The assessment also showed that extreme floods and droughts have become increasingly prominent, with record-breaking events recorded every year over the past five years.
In some regions, communities have had little opportunity to recover before another extreme event occurs.
Asia and Africa recorded some of the highest numbers of extreme water-related events and deaths, with major floods reported in countries including Nigeria and the Democratic Republic of the Congo.
Southern and Southeast Asia were also affected by tropical cyclones and intense monsoon rainfall, while parts of Eastern Europe, the Mediterranean and the Middle East experienced severe drought.
The report cited the catastrophic flooding recorded in the Texas Hill Country in July 2025, which killed more than 130 people, as well as Hurricane Melissa, which affected parts of the Caribbean, including Jamaica and Haiti, and caused more than 90 deaths.
The assessment warned that the risk of further extreme events could increase in 2026, with the strengthening of the El Niño phenomenon expected to raise the likelihood of drought in some regions and flooding in others.
The report was compiled using information from more than 60 countries, although the authors identified major gaps in water monitoring, particularly across Asia and Africa.
The WMO stressed that better measurement and monitoring would be essential for understanding changes in water availability and improving responses to growing climate-related risks.
Wayne Jenkins, quoted in the report, said the long-term decline in the amount of water stored on land had become increasingly evident since around 2016.
He stressed the importance of monitoring, noting that effective management of water resources depends on reliable information about how the global water cycle is changing.
Mattia Sacco of Curtin University, who was not involved in preparing the report, described the observed declines across major components of the global water cycle as alarming.
According to Sacco, worsening water quality and declining water availability could threaten biodiversity, ecosystems and the resilience of the planet.
The findings underline the growing connection between climate change and freshwater security, as instability in rivers, groundwater, glaciers and rainfall patterns increasingly affects societies that depend on predictable access to water.
