The Caspian Sea, the largest lake in the world, on the way to dryness

06/01/2021

A group of scientists warns that the Caspian Sea could lose up to a third of its surface. Climate change is evaporating more water than is flowing from the rivers into the Caspian Sea.

The Caspian has lost water since the 1970s. The rate of decline, however, was one or two centimeters per year. Now, a group of Dutch and German researchers have found that the rate is accelerating to six or seven centimeters a year and will increase in the next few decades.

"Our model predicts a drop in Caspian sea level of nine meters in an intermediate emission scenario [from CO₂] and 18 meters in a high emission scenario by the end of the century," says University of Bremen (Germany) researcher and co-author of this study on the evolution of this salt lake Matthias Prange.

The water of the Caspian depends on three main factors: The Volga River provides 90% of its water volume. Another significant contribution is that of winter rainfall.

On the other side of the balance are evaporation losses when you press the thermometer. Of the three, what is changing is the temperature, they show in the study, published in the scientific journal Communications Earth and Environment.

"In the case of the Caspian Sea, the effect of evaporation is by far the most important thing," says Prange. In fact, all indications are that winter rainfall in the northern part of the Volga basin will increase.

"Therefore, runoff from the river and its discharge into the Caspian Sea may increase slightly in the future. However, the greater effect of evaporation from the lake will lead to the projected decline in sea level," he completes.

An apparently paradoxical phenomenon is occurring here: while warming is causing an increase in the level of the oceans, the level of inland seas and large lakes will fall by the same effect of rising temperatures.