More than 50 percent of the world’s largest lakes are losing water, according to a groundbreaking new assessment recently released. The study also brings to light the main causes of this worrying trend.
The international team led by Fangfang Yao, from the Cooperative Institute for Research in Environmental Sciences (CIRES), attached to the University of Colorado at Boulder, in the United States, created a technique to measure changes in the water levels of almost 2,000 of the largest lakes and reservoirs in the world, which account for 95 percent of the total lake water storage on Earth.
The team combined three decades of observations from a suite of satellites with models to identify and quantify trends in lake storage globally.
Worldwide, freshwater lakes and reservoirs store 87% of the planet’s water, making them a valuable resource for both humans and terrestrial ecosystems. Unlike rivers, lakes are usually not well monitored in terms of hydrology, and yet they provide water for much of humanity, even more than rivers.
Despite the undeniable value of lakes, long-term trends and changes in water levels were largely unknown on a global scale until now.
The new study has been based mainly on observations of lakes made from space. (Photo: NASA)
For the new work, the team used 250,000 photographs taken from satellites between 1992 and 2020 to study the surface of 1,972 of the largest lakes on Earth. The study authors obtained data on water levels from nine satellite altimeters. Additionally, they used long-term water levels to reduce any uncertainty. For lakes without a long-term level record, they used recent water measurements.
The information collected allowed scientists to reconstruct the volume that the lakes had decades ago.
The result of the analysis of all this data is amazing: 53% of the world’s lakes have experienced a decrease in their amount of stored water.
The main culprits for that decline are not surprising: global warming and an unsustainable degree of water consumption by the human population.
The study is titled “Satellites reveal widespread decline in global lake water storage”. And it has been published in the academic journal Science. (Fountain: NCYT by Amazings)