Science1 publisher2 min readPublished
Three years of glacier loss equal a third of the world's annual freshwater withdrawals
Freshwater storage has been declining for ten years. The WMO's new report locates the loss in the slow reserves, groundwater and glaciers, that used to absorb bad years.
The Scientist · Science desk
What happened
- The WMO's annual State of Global Water Resources report finds Earth's freshwater storage, counting groundwater, lakes and rivers, soil moisture, vegetation and ice and snow, still declining after a decade.
- For a seventh year running, river basins with normal flow conditions were a clear minority, in a year the WMO ranks among the three driest for rivers in 35 years.
- The WMO expects the current El Nino to be the strongest since comparable records began four decades ago, arriving on top of the multiyear decline in stored water.
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Why it matters
- constraint Ten years of falling storage weakens the assumption that abstraction licences and reservoir rules are written against, that a dry year is followed by refill.
- exposure The loss is not spread evenly across users. Aquifer-dependent and glacier-fed basins carry it, and a global total averages away who is actually short.
- decision Governments now choose between funding monitoring in the areas the WMO flags as hard-hit and continuing to allocate water there on the thinnest data in the report.
The groundwater headline counts wells in both directions. WMO Secretary-General Celeste Saulo said "Groundwater tells a similar story: nearly two-thirds of monitored wells worldwide showed conditions outside the historical norm in 2025" [6]. A well sitting above its historical range counts in that two-thirds alongside one sitting below it, so the number describes how far conditions have moved from the norm, not how much water has gone. The report's directional statement is separate: groundwater levels in many parts of the world were in a multiyear decline [3]. The report does not say how much of that decline is pumping and how much is rainfall.
Glacier loss is easier to size. The WMO put cumulative global glacier mass loss between 2023 and 2025 at 1,400 gigatons of water, which it describes as about a third of the world's annual freshwater withdrawals [5]. Run that comparison backwards and annual withdrawals are roughly 4,200 gigatons [1]. The three-year loss averages about 470 gigatons a year [2], close to 11 percent of the volume the world takes out of rivers, lakes and aquifers each year [3]. The comparison is only a measure of scale. Ice lost from one mountain range does not reach a well in another basin. "A river basin is fed by water upstream, often in another country," Saulo said [18].
Precipitation, river flow and soil moisture respond to weather within days or weeks [10]. Groundwater and glaciers respond much more slowly, and Saulo called them the planet's "savings account" [9]. They have been "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 [7]. "We are spending our reserves," she said [8].
Flows split three ways in 2025. Around 36 percent of monitored basins ran normal discharge, an equal share ran below normal, and 21 percent ran above [12]. The two tails together account for 57 percent of basins [4]. Saulo said "The strengthening El Niño will increase the risk of drought in some areas and flooding in others" [14].
She also said "Weather respects no borders, and this is especially true for water," and pointed to "a glacier disaster in one country can lead to devastation in another, as we saw with the recent tragedy of China and Nepal" [17][19].
What to watch
- Whether the 2026 report shows below-normal discharge overtaking the normal share of basins as the El Nino runs its course.
- Whether glacier loss extends to a fifth consecutive year of significant mass loss across all regions.
- Whether the next storage estimate is published by region instead of as a single global total.