Which Greek lakes are “in red”
More than 50% of the world’s largest lakes are losing water, according to new research published in the journal Science. The main culprits for this are warming, unsustainable human consumption and sedimentation.
Researchers from the CIRES Institute at the University of Colorado at Boulder, Kansas State University, the University of Toulouse in France, and the KAUST University of Science and Technology in Saudi Arabia created a technique to measure water level changes in nearly 2,000 of the world’s largest lakes, natural and man-made, which account for 95% of the Earth’s total lake water storage. Among them, they also studied Greek ones, in which they detect a drying trend: Prespes, the artificial lake of Polyphytos and the artificial lake of Kremastos.
The team combined three decades of observations from an array of satellites with models to quantify trends in lake water storage globally. It used 250,000 snapshots of 1,972 of Earth’s largest lakes, captured by satellites between 1992 and 2020. They also collected measurements of water levels from nine satellite altimeters and studied these measurements over time to reduce any uncertainty. For lakes without long-term water level records, they used recent water measurements taken by satellites. Combining recent water level measurements with longer-term measurements of their area has allowed scientists to reconstruct the volume of the lakes decades ago.
According to the results, 53% of the world’s lakes, in both dry and wet regions, showed a decrease in their volume. The researchers liken this decline to the size of 17 Lake Mead, which is the largest man-made lake in the United States. Losses in wet tropical lakes and Arctic lakes suggest more widespread drying trends than previously realized. In artificial lakes this reduction is greater: almost two-thirds of them worldwide have experienced significant water losses.
Globally, lakes store 87% of the planet’s water, which makes them a valuable resource for the Earth’s ecosystem. Unlike rivers, the researchers note, lakes are not adequately monitored, although they provide water for a large portion of humanity. In fact, they estimate that about a quarter of the world’s population, i.e. two billion people, live in the basin of a drying lake, which indicates the need for changes in the sustainable management of water resources.
However, while the majority of lakes shrank, 24% saw a significant increase in water storage, mainly in sparsely populated areas in the interior of the Tibetan Plateau, the northernmost Great Plains in North America, and areas with newer man-made lakes such as basins. of the Yangtze River in China, the Mekong in Southeast Asia and the Nile.
Lead author Fangfang Yao, a fellow at the CIRES Institute and the University of Virginia, says the news is not entirely ominous. With this new method of monitoring water storage in lakes and the reasons behind it, scientists can give communities information on how they can better protect critical water sources and important regional ecosystems.
The researchers mention in their publication possible solutions to reduce the drying of the lakes and present the example of Lake Sevan in Armenia, where an increase in water storage has been observed over the past 20 years, which the scientists link to the legislation passed by the authorities of the 2000s to regulate water abstraction.
Source: RES-MPE
