The Caspian sea is evaporating faster
The water level in the Earth’s largest closed reservoir in the past 20 years falls to seven centimeters per year. The total decrease from 1996 was about 1.5 meters. The current level of just one meter above the record low levels of the late 1970s.
Article with the results of the analysis of long-term observations published in the journal Geophysical Research Letters.
According to the results of the new work, the average subsurface temperature near the Caspian sea increased by about 10C, if we compare the two studied time period: from 1979 to 1995 and from 1996 to 2015.
The authors believe that this increase is a manifestation of global warming that has affected the fact that the rate of evaporation has increased. This, in turn, led to the lowering of the water level.
“We as geologists are attracted to this place because here it is possible to build some kind of a General water balance, says Clark Wilson from the University of Texas at Austin. — The real cause of changes in water level for a long time is, most likely, evaporation, which is almost entirely controlled by temperature.”
The authors became interested in this problem when I was helping to calibrate the geophysical data of the satellite GRACE and noticed the heavy changes in the water level. They considered three main factors: the flow of water from rivers, precipitation and evaporation. By combining satellite measurements of water level, rainfall data and river water revenues, as well as the results of climate modeling, scientists have identified the impact of each factor on the observed level change during the period from 1979 to 2015. Evaporation was responsible for about half of the lowering of the water level, and further increase in temperature can aggravate the situation.