2:30 PM - 2:45 PM
[MIS01-14] Changes of temperature, precipitation and sea shores in the Caspian Sea region since 1970th
Keywords:Caspian Sea, Kara-Bogaz-Gol, climate change, sea level change, MODIS, remote sensing data
The historically observed the lowest Caspian Sea level was documented in 1977: -29 m below the World Ocean level. After almost five decades of the Caspian Sea level rise a new drop has been reached at the point: -28.5 m in 2023. We have examined mean seasonal temperature and precipitation in the region using the Climate Research Unit Reanalysis method. The general observed trend is increasing temperature in all seasons. The sea surface temperature raised on 3-4 degrees Celsius at the same time. On average, about 200 mm of precipitation per year observed in the open sea, 300-400 mm - on the western coast, up to 1700 mm - in the southwestern part of the sea, and only 100 mm at the eastern coast. The precipitation trends are different in time and space: increase of annual amount in the North and West and decrease or no change in the East and South. Changes in the seasonal distribution of precipitation are even more complex. Drought periods have become more frequent and longer. Evaporation from the sea surface on average per year is 5 times higher than incoming precipitation and river runoff.
Changes in the level of the Caspian Sea depend not only on local climatic conditions, but also on the flow of the Volga River, which, in turn, is regulated by the reservoir system. According to the Russian Hydrometeorological Service statistics, the river flow is going down last decades, in spite of precipitation growing in the main part of the river basin.
Coastline dynamics based on the remote sensing data from the 70s of the last century are available for analysis. We used Landsat and MODIS satellite images to monitor coastline dynamics. There are two shallow places with gentle slopes especially markable, where the sea level changes: Northern part and Kara-Bogaz-Gol Gulf. In the Northern part changes of the cast line follows climate change and Volga River flow. In Kara-Bogaz-Gol we observed consequences of a dam construction and destruction (1983). During the period of lowering the level of the Caspian Sea, the area of the bay was smaller than today. After the construction of the dam, the bay almost completely dried up (the dry area was 18,7 thousand km2), but quickly recovered after the dam destruction in 1984. However, since the beginning of this century, a steady trend towards a decrease in the level of the bay has been observed again. For today the area of the gulf is above 17 thousand km2, that is 91.3% from the maximum Gulf area, but still in 1.9 times more, than at the minimum Caspian Sea level in 1977.
For the North Caspian Sea (above 45 N) MODIS data is available from 2000. We compared minimum seasonal sea level in September. The maximum water area has been observed at the beginning of the period – 64,5 thousand km2. In 2023 it decreased to 52,8 thousand km2 (Figure 1). At Landsat images appearance and extinctions of small islands is clearly markable. The pace of the coastline change has accelerated last 3 years.
Taking into account the IPCC climate change projections, the Caspian Sea level further decline is possible, and can result in strong negative impacts for local communities, including dust storms, like at the desiccated bottom of the Aral Sea.
Changes in the level of the Caspian Sea depend not only on local climatic conditions, but also on the flow of the Volga River, which, in turn, is regulated by the reservoir system. According to the Russian Hydrometeorological Service statistics, the river flow is going down last decades, in spite of precipitation growing in the main part of the river basin.
Coastline dynamics based on the remote sensing data from the 70s of the last century are available for analysis. We used Landsat and MODIS satellite images to monitor coastline dynamics. There are two shallow places with gentle slopes especially markable, where the sea level changes: Northern part and Kara-Bogaz-Gol Gulf. In the Northern part changes of the cast line follows climate change and Volga River flow. In Kara-Bogaz-Gol we observed consequences of a dam construction and destruction (1983). During the period of lowering the level of the Caspian Sea, the area of the bay was smaller than today. After the construction of the dam, the bay almost completely dried up (the dry area was 18,7 thousand km2), but quickly recovered after the dam destruction in 1984. However, since the beginning of this century, a steady trend towards a decrease in the level of the bay has been observed again. For today the area of the gulf is above 17 thousand km2, that is 91.3% from the maximum Gulf area, but still in 1.9 times more, than at the minimum Caspian Sea level in 1977.
For the North Caspian Sea (above 45 N) MODIS data is available from 2000. We compared minimum seasonal sea level in September. The maximum water area has been observed at the beginning of the period – 64,5 thousand km2. In 2023 it decreased to 52,8 thousand km2 (Figure 1). At Landsat images appearance and extinctions of small islands is clearly markable. The pace of the coastline change has accelerated last 3 years.
Taking into account the IPCC climate change projections, the Caspian Sea level further decline is possible, and can result in strong negative impacts for local communities, including dust storms, like at the desiccated bottom of the Aral Sea.