The world’s water cycle is becoming increasingly unstable, with some regions facing severe shortages while others experience excessive rainfall and flooding, the United Nations has warned.
The warning was contained in the World Meteorological Organization’s (WMO) annual State of Global Water Resources report, which highlighted continued declines in freshwater storage and growing changes in rivers, groundwater and glaciers.
According to the report, 2025 was among the driest years for rivers globally in more than three decades. The year was also one of the warmest on record, while glaciers recorded significant ice loss across all regions.
The WMO said freshwater stored in groundwater, lakes, rivers, soil, vegetation, ice and snow continued its decade-long decline.
Some parts of the water cycle can respond quickly to changing weather conditions. Rainfall, river flows and soil moisture, for instance, can change within days or weeks.
However, the report raised particular concern about slower-moving water reserves such as groundwater and glaciers, which provide an important buffer during periods of drought.
WMO Secretary-General Celeste Saulo described these reserves as the planet’s “savings account”, warning that continued depletion could make water crises more difficult to manage.
They have served as “a buffer that absorbs bad years so that a single drought or a single dry season does not translate directly into a water crisis”, she told reporters.
Spending Our Reserves
Saulo warned that humanity is increasingly relying on these long-term reserves as water conditions become more unpredictable.
Now, “we are depleting that savings account”, she warned. “We are spending our reserves.”
Glaciers recorded another major decline in 2025, marking the fourth consecutive year of significant ice loss across all monitored regions.
Between 2023 and 2025, glaciers lost an estimated 1,400 gigatonnes of water globally. The amount is roughly equivalent to filling 560 million Olympic-sized swimming pools and represents about one-third of the world’s annual freshwater withdrawals.
Groundwater is also showing signs of growing stress. According to Saulo, nearly two-thirds of monitored wells around the world recorded conditions outside their historical range in 2025.
She said the decline in water reserves was occurring alongside an increase in disasters linked to water, including droughts and floods.
The WMO also warned that the current El Niño pattern could make the situation more challenging. The organisation expects the event to be the strongest recorded since comparable observations began about four decades ago.
El Niño is the warm phase of a naturally occurring climate cycle that typically develops every two to seven years. It is associated with unusually warm Pacific Ocean temperatures and can alter rainfall, winds and weather patterns across different parts of the world.
“The strengthening El Niño will increase the risk of drought in some areas, and flooding in others,” Saulo cautioned.
‘Abnormal’
Even before the current El Niño conditions intensified, rivers around the world were already displaying unusual patterns, according to the WMO.
The organisation said 2025 was among the three driest years for global river flows recorded over the past 35 years.
For the seventh consecutive year, only a minority of the world’s river basins recorded conditions considered normal.
About 36 percent of monitored basins had normal river flows, while another 36 percent recorded below-normal discharge. Around 21 percent experienced above-normal flows.
The WMO stressed that reliable data is essential for understanding how the global water cycle is changing, but noted that significant gaps remain, particularly in areas heavily affected by water-related events.
“Weather respects no borders, and this is especially true for water,” Saulo said, calling for “shared data, shared standards and shared early warnings”.
She explained that water systems often cross national boundaries, meaning developments in one country can affect communities elsewhere.
“A river basin is fed by water upstream, often in another country,” she pointed out.
She also noted that disasters involving glaciers can have consequences beyond the country where they occur, citing the recent tragedy involving China and Nepal as an example.
The WMO said the findings underline the need for stronger monitoring, international cooperation and improved early-warning systems as the global water cycle becomes increasingly unpredictable.
Source: AFP
