Global river levels lowest in more than 3 decades

The World Meteorological Organization (WMO) reported on global water scarcity, with water levels of major tributaries to the Amazon - the largest river on Earth - at record lows.

One of the Amazon's main tributaries, the Negro River, has dropped to its lowest level ever recorded at 12.66 meters (41 feet), Brazil's geological agency said on October 4. It is the lowest since measurements began 122 years ago. The water level is falling at a rate of about 17.8 centimeters (7.8 inches) per day.

The Rio Negro River in Brazil, taken in September 2023. (Photo: Jesper Sohof/Shutterstock).

The WMO's "State of Global Water Resources 2023" report found that rivers around the world were "characterized by drier-than-normal to normal conditions" last year, compared with data on the amount of water flowing through rivers at any point since 1991.

According to the report, 45% of the world's rivers were found to be flowing at or well below normal levels. Meanwhile, many countries in eastern Africa have experienced devastating floods. The report said the heavy rainfall that led to the floods was "likely caused by the El Niño phenomenon." Human-caused climate change is one of the causes of extreme weather.

"As temperatures rise, the hydrological cycle has accelerated. It has also become more erratic and unpredictable, and we are facing increasing problems of too much or too little water," said WMO Secretary-General Celeste Saulo in a statement.

'Water is a warning signal about climate change. We are receiving an urgent signal in the form of increasingly extreme rainfall, floods and droughts that are causing severe damage to lives, ecosystems and economies. Melting ice and glaciers are threatening the long-term water security of millions of people ,' said Ms. Saulo, adding that urgent action is needed to limit this situation.

Urgent action is being called for to better understand and study what is happening to the world's freshwater resources. While the WMO report is considered comprehensive, there are still many gaps in data due to lack of observation or sharing, with Africa, South America and Asia under-represented.

Ms Saulo said that 'too little is known about the true state of the world's freshwater resources' , and it is difficult to 'manage what cannot be measured'. Therefore, there is a need to improve monitoring, data sharing and cross-border cooperation in this area.

According to World Weather Attribution (WWA), climate change is fueling extreme weather events. Linking climate change to individual droughts is difficult. Water availability depends on many factors beyond temperature and rainfall, with natural weather systems also playing a role. That was the case with the drought in southern Africa in early 2024. But heat waves caused by climate change can exacerbate droughts by drying out the ground, causing the air above to warm more quickly and the heat to become more intense.

During hot weather, water demand increases, especially from farmers, putting additional strain on water supplies. In parts of East Africa, the rainy season was absent for four straight years from 2020 to 2022 as the region experienced its worst drought in 40 years, displacing 1.2 million people in Somalia. Climate change has made such droughts at least 100 times more likely.