A fisherman walks across a dry patch of land in the marshes in Dhi Qar province, Iraq, Sept. 2, 2022.Anmar Khalil / AP

The planet is entering an era of global "water bankruptcy," a United Nations research agency said in a new report, which warns that humans` water use over the long term has exceeded the renewable water sources worldwide and, potentially, passed a point of no return.

"Bankruptcy" means the Earth`s water repositories, such as rivers, lakes and aquifers, are being depleted at faster rates than they can be restored, according to the report from researchers at the United Nations University`s Institute for Water, Environment and Health (UNU-INWEH).

"In many regions, human-water systems are already in a post-crisis state of failure," the report`s authors wrote.

That failure, they say, is a result of decades of overstretching, in which "societies have withdrawn more water than climate and hydrology can reliably provide" while environmental factors like pollution shrunk the amount of water that can be safely used by degrading its quality. The consequences are measurable, especially in deeply affected regions in the Middle East and North Africa, parts of South Asia and the American Southwest.

There are dozens of major rivers that fail to reach the sea for parts of the year, and many river basins and aquifers have been "overdrawing" their shares of water for at least the last five decades, according to the report. Half of the world`s large lakes have lost water since the early 1990s, a pattern of decline that impacts roughly 25% of the global population. Researchers say increased demand for that water, as well as changing inflows and rising temperatures, are largely to blame.

While river basins also experience alterations in their typical flow, the wetland environments that scientists describe as traditional "shock absorbers" for the water cycle are disappearing, too. More than 1 billion acres of natural wetlands have been erased over the last 50 years - an area is roughly equal to the size of continental Europe - threatening the communities they normally help to protect from floods and drought.

"These are not simply signs of stress or episodes of crisis," the report said. "They are symptoms of systems that have overspent their hydrological budget and eroded the natural capital that once made recovery possible, with knock-off effects for food prices, employment, migration and geopolitical stability."

About 75% of the human population reside in countries that have been classified as "water-insecure" or "critically water-insecure," the report says. That means their nations cannot reliably provide them with enough water that meets basic safety and quality standards.

Within that group, some 4 billion people face severe water scarcities for at least one month each year, 3.5 billion lack safely managed sanitation and 2.2 billion lack safely managed drinking water, the report says. Another 3 billion live in areas where the total water storage is declining or unstable, and at least half of the world`s food is produced in those same regions.

"Millions of farmers are trying to grow more food from shrinking, polluted, or disappearing water sources," said Kaveh Madani, director of the UNU-INWEH and the report`s lead author, in a statement. "Without rapid transitions toward water-smart agriculture, water bankruptcy will spread rapidly."

The report recommends a combination of efforts to address the water bankruptcy, including aiming to restore what has been lost, staving off ongoing depletion and adapting to the amount of usable water that exists now.

"Water bankruptcy is becoming a driver of fragility, displacement, and conflict," said U.N. Under-Secretary-General Tshilidzi Marwala in a separate statement. "Managing it fairly - ensuring that vulnerable communities are protected and that unavoidable losses are shared equitably - is now central to maintaining peace, stability, and social cohesion."