'We Are Spending Our Reserves,' WMO Chief Warns as UN Drops Global Water Report

The world's water cycle "has become more erratic and unpredictable," and recent trends have "serious implications for people and economies in the future," the United Nations' weather agency said Thursday, announcing the release of its annual report on one of the planet's most important natural resources.

Speaking at the launch of the "State of Global Water Resources 2025," World Meteorological Organization (WMO) Secretary-General Celeste Saulo explained that "some parts of this cycle—such as precipitation, river flow, soil moisture—are fast. They respond to weather within hours, days, weeks. Others, like groundwater and glaciers, are slow. They accumulate or decline over seasons to decades or longer."

"Traditionally, these slow reserves have acted as the planet's savings account: 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 continued. "One of the central stories of the 2025 report is what is happening to that savings account. And the simple answer is that we are depleting it. We are spending our reserves."

According to the WMO's new report, terrestrial water storage—or the total stored in groundwater, lakes, rivers, soil moisture, vegetation, ice, and snow—has been falling since the mid-2010s. Saulo stressed that "this is not a single bad year, but it is a persistent, decadelong signal."

The agency also found that 2025 was among the driest years for river discharge worldwide in more than three decades, with below-normal flows over a third of the global basin area—and for the seventh straight year in a row, the number of river basins with "normal" conditions was in the minority.

Last year was also the fourth straight to feature widespread glacier loss across all regions. The WMO noted that the losses from 2023-25 could fill about 560 million Olympic-sized swimming pools—or about a third of annual freshwater withdrawals.

The report also "shows that water-related extreme events continue to devastate communities and economies," Saulo noted, highlighting the Early Warnings for All Initiative. "Over the past five years, Asia and Africa have accounted for at least half of all reported hydrological extreme events and more than 80% of associated deaths. And precisely these regions often lack the observations necessary for forecasts and early warnings."

Her comments came a day after the death toll from the flooding disaster in Tibet and Nepal topped 1,400. Experts have emphasized that tragedy's connection to the fossil fuel-driven climate crisis, with University of Pennsylvania professor Michael Mann writing that the "glacial collapse and deluge... was not a freak weather event; it was the structural failure of a mountain itself, nature's latest commentary on the deadly consequences of human-caused planetary warming."

That warming has also intensified the naturally occurring warm phase of a key pattern in the Pacific Ocean called El Niño, according to a study published last month. The WMO chief warned in her Wednesday remarks that "the strengthening El Niño will increase the extremes—drought in some countries and floods in others."

The agency's latest forecast, also released Wednesday, anticipates an "exceptionally high likelihood of nearly 100%" that the warm phase will persist through to February 2027. UN Secretary-General António Guterres said that "El Niño is being supersized before our eyes. The science leaves no room for doubt: The planet is in uncharted waters, and those waters are heating up."

While the related releases generated calls for action, Saulo said that "it is not all bad news. Some regions showed improvement in 2025," pointing out that "parts of South America saw a partial recovery in water storage during 2025 after a severe multiyear deficit," while "Central and Southern Africa maintained much-above-normal water levels across several major lakes."

Still, action is needed. As Saulo put it: "The State of Global Water Resources report calls for a sense of urgency, not panic. The buffers that have historically protected water security—snow, ice, groundwater—are eroding in many regions on a timescale of years, not overnight. We have a genuine window for action: expanding early warning coverage; investing in the hydrological monitoring infrastructure; and opting for water management policies to address both water supply and use/overuse."

"My concluding message is that this report exists because members share their data and their science," she said. "This level of understanding—global, standardized, comparable year to year—did not exist a decade ago. It is the product of sustained international cooperation under WMO's mandate. And my last call is for all of you to continue to invest in it."