Earth's water cycle is becoming increasingly erratic.

The United Nations said on October 7 that climate change is making the water cycle more unpredictable, with floods and droughts becoming more intense.

Last year, the world's rivers were the driest in more than 30 years, glaciers lost their largest ice mass in half a century and there were numerous floods, according to the United Nations' World Meteorological Organization (WMO). " We are receiving a warning signal in the form of increasingly extreme rainfall, floods and droughts that are taking a heavy toll on lives, ecosystems and economies ," said WMO Secretary-General Celeste Saulo.

Rhone glacier in the Swiss Alps, September 30. (Photo: Fabrice Coffrini/AFP).

The warming of the Earth's atmosphere is making the water cycle "more erratic and unpredictable," Saulo said . Last year was the hottest on record, with high temperatures and widespread dry conditions that led to prolonged drought.

These extreme events are influenced in part by natural climate conditions including La Nina and El Nino, but are also increasingly influenced by human-caused climate change . 'A warmer atmosphere holds more moisture, which favors heavy rains. Faster evaporation and drier soils exacerbate the problem of drought ,' says Saulo.

Too much or too little water is putting many countries in increasingly difficult situations. Last year, Africa was the continent hardest hit in terms of casualties. In Libya, two dams collapsed in a massive flood in September 2023, killing more than 11,000 people and affecting 22% of the population, according to the WMO.

Currently, 3.6 billion people lack access to fresh water at least once a month, according to the United Nations. That number is expected to rise to more than 5 billion by 2050. Over the past three years, more than 50 percent of river basins have been drier than normal. Meanwhile, lake flows have been below normal in many parts of the world over the past half-decade.

Rising temperatures mean glaciers are melting at an unprecedented rate, losing more than 600 billion tons of water, the worst in 50 years of observation, according to preliminary data from September 2022 to August 2023. "Melting ice and glaciers threaten the long-term water security of millions of people. But we are not taking the urgent action needed ," Saulo said.

In addition to curbing greenhouse gas emissions that cause global warming, the WMO wants the world's freshwater resources to be better monitored so that early warning systems can minimize damage to people and wildlife.

Stefan Uhlenbrook, director of the WMO's hydrology, water and ice division, warned that returning to a more natural and balanced water cycle would be difficult. 'The only thing we can do is stabilize the climate, which is an enormous challenge ,' he said.