At least half of the largest lakes on the planet are retreating due to climate change. Over the past 28 years, 22 gigatons per year of water have been lost due to global warming and human-related consumption, making 50% of the world's largest lakes shrinking and at risk of disappearing.
Regarding the trend of water storage in man-managed reservoirs, significant losses have been discovered in almost two thirds of the large reserves, mainly due to the accumulation of sediments.
At least half of the largest lakes on the planet are retreating due to climate change
Reversing this worrying trend is possible, as demonstrated by the case of Lake Sevan in Armenia, which has grown in the last 20 years thanks to new laws regulating the withdrawal of water since the early 2000s.
In the study, in particular, they started from 250,000 satellite images taken between 1992 and 2020 showing the surface extension of 1,972 of the largest lakes in the world. Lakes cover only 3% of the land, yet they store 87% of the fresh water present in the liquid state on the earth's surface.
To monitor them, researchers have developed a new technique, very useful for water management, which combines satellite observations with climate and hydrological models.
2 billion people living near lakes receding reservoirs at risk
The phenomenon, which puts nearly 2 billion people living near receding reservoirs at risk, is described in a study published in Science by an international team led by Fangfang Yao of the University of Colorado at Boulder.
The measurements of the water level obtained with nine satellite altimeters, in order to be able to calculate the volume of the lakes in the last decades, have given the necessary results. The findings reveal a decline in water stored in 53 percent of the world's large lakes, located in both wet and dry areas, with larger-than-expected losses in the Arctic and wet tropics.
A significant increase in water is recorded in only 24% of the large lakes, which however are mostly located in remote and sparsely populated regions such as the Tibetan plateau.