LONDON, May 18 (Reuters) – More than half of the world’s great lakes and reservoirs have shrunk since the early 1990s, mainly due to climate change, raising concerns about water for agriculture, hydropower and human consumption, shows a study published on Thursday.
A team of international researchers reported that some of the world’s most important sources of fresh water—from the Caspian Sea between Europe and Asia to South America’s Lake Titicaca—were losing water at a cumulative rate of about 22 gigatons per year for nearly three decades. That’s about 17 times the volume of Lake Mead, America’s largest reservoir.
Fangfang Yao, a surface hydrologist at the University of Virginia who led the study in the journal Science, said 56% of the decline in natural lakes was driven by global warming and human consumption, with warming “the biggest part of it”.
Climate scientists generally believe that the world’s dry areas will become drier under climate change and wet areas will get wetter, but the study found significant water loss even in humid areas. “This should not be overlooked,” Yao said.
Researchers assessed nearly 2,000 Great Lakes using satellite measurements combined with climate and hydrological models.
They found that unsustainable human use, changes in rainfall and runoff, sedimentation and rising temperatures have driven lake levels down globally, with 53% of lakes showing a decline from 1992 to 2020.
Nearly 2 billion people living in a drying lake basin are directly affected, and many regions have faced shortages in recent years.
Scientists and campaigners have long said that preventing global warming above 1.5 degrees Celisus (2.7 degrees Fahrenheit) is necessary to avoid the most catastrophic consequences of climate change. The world is currently warming at a rate of about 1.1 C (1.9 F).
Thursday’s study found that unsustainable human use was drying up lakes such as the Aral Sea in Central Asia and the Dead Sea in the Middle East, while lakes in Afghanistan, Egypt and Mongolia were hit by rising temperatures, which could increase water loss to the atmosphere.
Water levels rose in a quarter of the lakes, often as a result of damming in remote areas such as the Inner Tibetan Plateau.
Reporting by Gloria Dickie in London; editing by Barbara Lewis
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