ONTARIO, Canada: Decades of overuse and environmental damage have pushed the world's freshwater systems past a critical tipping point, leaving billions of people exposed to worsening shortages and economic risks, according to new research from the United Nations.

Researchers at the United Nations University Institute for Water, Environment and Health warned on January 20 that the planet is entering an era of irreversible water "bankruptcy", as lakes, rivers, glaciers, wetlands, and underground aquifers are depleted faster than they can recover.

Nearly three-quarters of the global population now live in countries deemed "water insecure" or "critically water insecure", the report said. Around four billion people experience severe water scarcity for at least one month each year.

"Many regions are living beyond their hydrological means, and many critical water systems are already bankrupt," said Kaveh Madani, the institute's director and lead author of the report.

"By acknowledging the reality of water bankruptcy, we can finally make the hard choices that will protect people, economies, and ecosystems," he said.

The study said the world's water supplies are "already in a post-crisis state of failure" following decades of unsustainable extraction. Natural water "savings" held in aquifers, glaciers, soils, wetlands, and river systems have been steadily drawn down, while pollution has further degraded remaining resources.

The strain is especially acute in agriculture. More than 170 million hectares of irrigated cropland — an area larger than Iran — are experiencing "high" or "very high" water stress, the report found. Damage linked to land degradation, groundwater depletion, and climate change now costs the global economy more than US$300 billion annually.

The researchers said three billion people live in regions where water storage levels are unstable or declining. Those same areas account for more than half of the world's food production, raising concerns about future food security. Salinization, often driven by poor irrigation practices, has already degraded more than 100 million hectares of cropland worldwide.

According to the report, current approaches to managing water resources are no longer adequate. Rather than aiming to "return to normal", the authors called for a new "global water agenda" focused on limiting damage, prioritising resilience, and adapting to long-term scarcity.

The researchers argued that water policy must shift away from short-term crisis responses toward systemic change, recognising water as a finite resource that underpins economic stability, ecosystems, and human health.

Not all experts agreed that the report fully captured the roots of the crisis. Jonathan Paul, a geoscience professor at Royal Holloway, University of London, said the analysis overlooked a key driver.

"The elephant in the room, which is mentioned explicitly only once, is the role of massive and uneven population growth in driving so many of the manifestations of water bankruptcy," he said.