From floods to drought: UN warns that the water cycle is becoming more extreme

The water cycle—its passage through solid, gaseous, and liquid states that breathes life into the planet—is “becoming increasingly irregular and extreme” on Earth, warns the World Meteorological Organization ( WMO ). This involves “fluctuations ranging from intense rainfall to periods of drought,” according to a report by this United Nations-affiliated organization, prepared using data from the meteorological services of 60 countries and other scientific institutions. This document, the WMO notes, highlights “the cascading effects that both excess and scarcity of water have on economies and society.”

This transition from scarcity to excess was fully experienced in Spain in 2024, the year focused on in this Wednesday's report. Because it went from a severe drought in a considerable part of the country to a disastrous cold snap in the Valencian Community in the fall that left more than 230 fatalities and €17.5 billion in economic losses, as the WMO report points out. In fact, 70% of the fatalities caused in Europe (335) by floods were concentrated in this episode of torrential rains on the Mediterranean coast, according to data collected by the WMO in this analysis presented this Thursday.

The study details that in 2024, only about a third of the world's river basins experienced "normal" conditions, taking the period between 1991 and 2020 as a reference. "In the rest, the recorded values ​​were either above or below normal, reflecting a clear imbalance for the sixth consecutive year," notes the WMO.

Well-below-normal flows were observed in key river basins, such as the Amazon, San Francisco, Paraná, and Orinoco rivers in South America, and the Zambezi, Limpopo, Okavango, and Orange rivers in southern Africa, the organization explains. In contrast, flooding was reported in large areas of West Africa, particularly in the Senegal, Niger, and Volta river basins, and Lake Chad. “In central Europe and parts of Asia, river flows were above normal, and flooding episodes occurred in some major basins, such as the Danube, Ganges, Godavari, and Indus,” the WMO notes.

“The world’s water resources are under increasing pressure, and at the same time, the most extreme water-related hazards are having a growing impact on lives and livelihoods,” writes WMO Secretary-General Celeste Saulo in the report’s foreword.

The impact of climate change on the planet's rainfall patterns due to greenhouse gases emitted by humans, primarily through the burning of fossil fuels, is not entirely clear. However, scientists have determined that global warming is worsening extreme events, such as droughts and torrential rains , and making them more frequent and intense.

“Water sustains our societies, drives our economies, and strengthens our ecosystems,” Saulo recalls, emphasizing the “critical need to improve data sharing on river flow, groundwater, soil moisture, and water quality, which remain poorly monitored.” “Without data, we risk acting in the dark,” notes the WMO chief. The WMO estimates that some 3.6 billion people lack adequate access to water for at least one month a year, “a number that is expected to rise to over 5 billion by 2050.”

Glaciers

The study not only addresses extreme events, but also longer-range phenomena that are a clear indicator of the warming process the Earth is experiencing. “In 2024, for the third consecutive year, widespread glacier mass loss was observed across all regions,” warns the WMO. “Many regions with small glaciers have already reached or are about to exceed peak water, i.e., the point at which a glacier reaches its maximum annual runoff rate, after which the rate declines as a result of glacial retreat,” the organization adds. “In total, 450 gigatons were lost, equivalent to a massive block of ice seven kilometers high, seven kilometers wide, and seven kilometers deep, or a volume of water sufficient to fill 180 million Olympic-sized swimming pools.”

Furthermore, the WMO focuses on the pressure on groundwater due to "over-extraction," which is a problem because it "reduces future availability" for communities and ecosystems. "Only 38% of wells (out of a sample of 37,406 from the 47 countries that provided groundwater data) showed normal levels; the rest recorded excessive abundance or scarcity of water," the organization concludes.