International team of scientists research fluctuations in water levels in the Caspian Sea
The increase in the temperature due to climate changes has caused the slow evaporation of the Earth’s largest inland water reservoir, find scientists from USA, Russia, France and Azerbaijan. The results of recent joint studies in the field of fluctuations in the level of the Caspian Sea are published in the journal of the American Geophysical Union "Geophysical Research Letters".
Scientific interest was attracted by multimeter water level variations in the Caspian Sea, which were detected when processing data from two NASA’s GRACE satellites and comparing them with surface measurements.
In 1996-2015, the water level decreased at a rate of 7 centimeters per year, and by the end of the 2015, the water level had dropped totally by almost 1.5 meters.
The current figure exceeds only a meter the critical estimate registered in the late 1970s when sea level fell by 29 meters.
Such a wide range of changes has been explained by the high rate of evaporation provoked by the growth of surface air temperature. In particular, during the period under consideration, the average temperature over the Caspian Sea increased by approximately 1°C as compared with 1979-1995.
The lead author of the study Jianli Chen from the Center for Space Research and geophysicist Clark Wilson of the Jackson School of Geosciences have analyzed the influence of the three major factors on the water level in the Caspian sea: the flow of rivers flowing into the sea, amount of precipitation and rate of evaporation.
The climate model used by scientists has helped to discover that evaporation is half responsible for lowering the water level, and at the current rate, the sea level risks to reach again the historical minimum.
Evaporation will have the most negative impact on the northern zone, since the depth there is less than 5 meters there. According to forecasts, with an annual decline in the water level by 7 centimeters, it will take near 75 years for the northern part to dry out at all.
Caspian Sea is a home for many unique ancient biological species originated from the Mesozoic era approximately 300 million years ago, when the sea was a part of the Tethys Ocean. Although most of them inhabit the southern and middle regions, some species of fish, including 90 percent of the world's sturgeon, migrate to the northern shallows during spawning.
According to the researchers, the drop in sea level will also affect the Turkmen Gulf of Kara-Bogaz-Gol, containing the richest natural deposits of sea salts.
In the near future, geophysicists and oceanologists will continue to forecast changes in the level of the Caspian sea using climate modeling and monitoring data.
