Earth’s water cycle is increasingly erratic

Last year, the world’s rivers were the driest in more than 30 years, glaciers lost the largest volume of ice in half a century and numerous floods occurred, according to the United Nations’ World Meteorological Organization (WMO). United Nations. “We are receiving warning signals in the form of increasing extreme rainfall, floods and droughts that are causing heavy human, ecological and economic damage,” said WMO Secretary-General Celeste Saulo.

The warming of the Earth’s atmosphere causes the water cycle to “become more erratic and unpredictable,” Saulo said. Last year was the hottest year on record, with high temperatures and widespread dry conditions causing a prolonged drought.

These extreme events are partly influenced by natural climate conditions including La Nina and El Nino phenomena, but are also increasingly influenced by human-caused climate change. “A warmer atmosphere contains more moisture, which favors heavy rains. Faster evaporation and drier soils exacerbate the problem of drought,” Saulo said.

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

Currently, each year, 3.6 billion people do not have enough fresh water at least once a month, according to the United Nations. This number is expected to increase to more than 5 billion by 2050. In the past three years, more than 50% of river basins have been drier than normal. Meanwhile, lake flows have fallen below normal levels 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 observations, 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 have not yet taken the necessary urgent actions,” Saulo said.

In addition to limiting greenhouse gas emissions that cause global warming, 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 WMO’s hydrology, water and ice department, warns that returning to a more natural and balanced water cycle is difficult. “The only thing we can do is stabilize the climate, which is a huge challenge,” he said.