Where will water come from if rivers run dry? Climate change and growing demand are putting pressure on the world’s rivers, but nature may offer part of the solution.
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From South America’s Amazon to the Rhine in Europe and Africa’s Nile, heat and drought are transforming rivers into barren landscapes, exposing long-submerged shipwrecks and allowing people to walk on riverbeds. In 2025, rivers worldwide had one of their driest years in over three decades. This year, amid record summer temperatures, Rhine water levels were so low, it disrupted inland shipping.
Image: Michael Probst/AP Photo/picture alliance
As humans heat the planet by burning fossil fuels, rainfall patterns are shifting, and droughts intensifying. Warmer temperatures also speed up evaporation, while shrinking snowpacks and glaciers in mountains where rivers rise mean less freshwater availability downstream. Heavy rain, flash floods and sudden glacial collapse are also causing rivers to swing between too much and too little water.
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When rivers rise too quickly and burst their banks, the consequences can be deadly for nearby communities. This is similar to what happened after the recent catastrophic glacier collapsed in a river valley in Nepal, killing thousands. But too little water puts a strain on hydropower production, drinking water supplies, agriculture, shipping, fisheries and the species living in rivers.
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River heat waves are also becoming more frequent and intense than 40 years ago. Warmer water and lower water levels harm cold-water fish such as trout and salmon, reducing reproduction and causing die-offs. Warmer water also raises drinking-water treatment costs. In 2022, a combination of pollution and heat triggered a toxic algal bloom in the Oder River, which flows through Poland and Germany.
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Pollution from agriculture and industry, water over-extraction and urbanization are putting rivers under increasing stress. Rivers like the Mekong in Southeast Asia have been straightened and built up, destroying floodplains and wetlands that reduce flooding and store water during dry spells. This makes rivers less resilient overall and can worsen flooding and drought.
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Healthy rivers and their floodplains protect the climate in other ways. They feed forests and wetlands, which store vast amounts of planet-warming CO2. Rivers also transport decaying organic matter and soil to the ocean, where some of this material is stored in seabed sediments, playing an important role in the global carbon cycle.
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For millions of people, rivers are essential to daily life. They provide food, transport, irrigation for agriculture, water to power industry, as well as water to drink. About a third of global food production and 40% of global fish consumption depends on rivers. Trees along riverbanks and rivers themselves also provide a cooling function for communities.
Image: Kaikeo Saiyasane/Xinhua/picture alliance
Just as building around rivers can worsen drought and flooding, restoring wetlands, riverbanks and floodplains can make landscapes more resilient to them. In Germany, restoring 90 kilometers (56 miles) of the Lower Havel River and its wetlands improved water quality and revived habitats for endangered species. China’s Yangtze River restoration and fishing ban have also helped the river recover.
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Removing dams can help rivers recover by reconnecting habitats and allowing fish and other species to move freely. Though freshwater habitats cover less than 1% of Earth, they support about 10% of species, creating resilient ecosystems better able to adapt to climate shifts. After four dams were removed from California’s Klamath River, thousands of salmon returned to their habitats upstream.
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The Okavango River flows from Angola to Botswana’s Kalahari Desert, supporting abundant wildlife, including hippos and elephants and providing water for a million people. It is one of the world’s few untouched river ecosystems. Today, only a third of the world’s longest rivers remain free-flowing. Without stronger protection, half of humanity could face severe water scarcity by 2030.
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Edited by: Sarah Steffen
