Due to climate change: global water cycle out of joint

Geneva. The global water cycle is out of balance, according to a report by the World Meteorological Organization (WMO). About two-thirds of rivers carried either too little or too much water in 2024—the hottest year to date. It is the sixth consecutive year of increasingly unpredictable and extreme events.

The main cause is climate change, said WMO water expert Stefan Uhlenbrook. Warmer oceans mean higher evaporation, and a warmer atmosphere can also hold more water. This could lead to both droughts and more intense precipitation.

In Central Europe and Africa (except in the south of the continent) as well as in parts of Asia, it was wetter in 2024 than the long-term average (1991 to 2020), according to the WMO report on global freshwater resources.

The WMO commemorates the floods in Europe. A third of the European river network has exceeded the flood threshold. Extreme weather events included flash floods in Bavaria in June 2024 and heavy rains that led to evacuations in Saarland and Rhineland-Palatinate.

In September, Storm Boris brought as much rainfall in Poland, Germany, the Czech Republic, and northeastern Romania in five days as would normally fall in three months. At the end of October 2024, heavy rainfall in Valencia, Spain, caused devastating floods, killing at least 232 people. Damage in many countries amounted to billions of euros.

In contrast, the Amazon region and other parts of South America and South Africa experienced severe droughts last year. According to the UN Water Agency, 3.6 billion people – a good 40 percent of the world's population – already lack enough water for at least one month of the year. This number is expected to rise to 5 billion by 2050.

2024 was also the third consecutive year of widespread glacier loss, not just regionally but in all regions of the world. Figuratively speaking, the total ice loss corresponds to the volume of an ice cube with a side length of 7 kilometers. This raises sea level by about 1.2 millimeters. Many areas with smaller glaciers have already reached their peak melting point – after that, water runoff decreases because the glaciers have become too small.

RND/dpa