LONDON: A new study has found that more than half of the world’s large lakes and reservoirs have shrunk since the early 1990s, chiefly because of climate change, intensifying concerns about water for agriculture, hydropower, and human consumption.
According to AL Jazeera, world researchers reported on Thursday that some of the world’s most significant freshwater sources – from the Caspian Sea between Europe and Asia to South America’s Lake Titicaca – lost water at approximately 22 gigatonnes per year for nearly three decades.
That is about 17 times the volume of the largest reservoir in the US States – Lake Mead.
The study published in ‘Science’ found unsustainable human use of dried-up lakes, such as the Dead Sea in the Middle East and the Aral Sea in Central Asia. In contrast, lakes in Afghanistan, Egypt, and Mongolia were hit by increasing temperatures, which can raise water loss to the atmosphere.
Water levels are high in a quarter of the lakes too, often due to dam construction in remote locations such as the Inner Tibetan Plateau.
Natural lakes and dams store about 87% of the Earth’s freshwater, although they cover just 3 % of the planet’s surface. The report was based on satellite pictures data collected between 1992 and 2020.
Fangfang Yao, the surface hydrologist at the University of Virginia who led the study, said 56% of the reduction in natural lakes was driven by climate warming and human consumption, with warming “the larger share of that.”
Climate scientists generally think that the globe’s arid areas would become drier under climate change and wet areas would get wetter, but the study found important water loss even in humid regions.
Yao said, “This shouldn’t be overlooked.”
Scientists assessed almost 2,000 large lakes using satellite measurements combined with climate and hydrological models. They found that unsustainable human use, changes in rainfall and run-off, sedimentation, and increasing temperatures have driven lake levels down globally, with 53% of lakes showing a reduction from 1992 to 2020.
