A study released on Thursday reveals that over 50% of the world’s largest lakes and reservoirs have shrunk since the early 1990s. This has largely been caused by climate change and raises concerns about water for agriculture, hydropower, and human consumption. The study, conducted by an international team of researchers, found that freshwater sources, such as the Caspian Sea between Europe and Asia and Lake Titicaca in South America, have lost water at a cumulative rate of about 22 gigatonnes per year over nearly three decades, which is approximately 17 times the volume of Lake Mead, the largest reservoir in the United States.
The study, published in the journal Science, was led by Huangfang Yao, a surface hydrologist at the University of Virginia, who said that 56% of the decline in natural lakes was caused by climate change. The study combined satellite measurements with climate and hydrological models to assess approximately 2,000 large lakes globally. It found that unsustainable human use, changes in rainfall and runoff, sedimentation, and rising temperatures are driving the lake, causing water levels to fall. As a result, 53% of lakes have shown a decline between 1992 and 2020, with about two billion people living in dry lake basins directly impacted.
Scientists and campaigners have long pointed out this problem, and preventing global warming above 1.5 degrees Celsius (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 degrees Celsius (1.9 degrees Fahrenheit).
The study found that human use is drying up unsustainable lakes, including the Aral Sea in Central Asia, the Dead Sea in the Middle East, and lakes in Afghanistan and Egypt. Mongolia and Mongolia will be hit by rising temperatures, which could increase water loss to the atmosphere. Rising water levels in a quarter of the lake are often the result of dam construction in remote areas such as the Inner Tibetan Plateau.
The study highlights the urgent need to address climate change to protect freshwater sources for agriculture, hydropower, and human consumption.