Changes in the moisture of the Caspian region of Russia due to global warming

Since the end of the twentieth century, the climate system of the planet has been experiencing significant changes in air temperature, due to anthropogenic emissions of greenhouse gases into the atmosphere, and changes in the precipitation regime. Our research covers the Caspian region of Russia, which belongs to the southern regions of the country, where one of the highest rates of air temperature increase is observed. The Caspian region includes the Astrakhan region, Kalmykia and Dagestan. To assess the upcoming changes, the average daily air temperature and precipitation were taken, as well as the average monthly values of water vapor elasticity, total cloud cover for the points of Astrakhan, Elista, Yashkul, Lagan, Makhachkala, Buinaksk, Derbent and Akhty. To assess changes in natural areas, we used the Budyko radiation dryness index. Changes in agriculture were estimated using the Selyaninov hydro-climatic index. It was revealed that the upcoming changes in the climate system, based on the data of the ensemble of models (CMIP5), will lead to an increase in the radiation balance, in the average annual amount of precipitation, in the sum of temperatures of more than 10 °C by the end of the century. Analysis of the dynamics of the Budyko index showed that by the end of this century, the Astrakhan region will still belong to the zone of subtropical deserts. Depending on which climate scenario the global climate system will develop, the region of Kalmykia may move from the zone of subtropical deserts to the zone of subtropical semi-deserts. The territory of Dagestan currently belongs to the zone of subtropical semi-desert. With the development of the climate scenario RCP 4.5, this territory will tend to the climatic conditions of the subtropical steppe zone (K = 2-3). In the development of the RCP8. 5 scenario, the territory of Dagestan will remain a zone of subtropical semi-deserts, with a tendency to transition to a zone of subtropical steppes. The readings of the Selyaninov hydro-climatic index, calculated for the period 2011-2030, indicate a continued deterioration of the moisture turnover conditions for the Astrakhan region and Dagestan in all scenarios. The humidity regime of the Astrakhan region will gradually deteriorate. As a result, irrigation - type agriculture will dominate in the Astrakhan region, while dry agriculture will dominate in Dagestan. According to the RCP 2.6 and RCP 8.5 scenarios, Kalmykia will move from an irrigation farming zone to a dry farming zone. By the end of the century, the humidity conditions of the Astrakhan region and Dagestan will deteriorate even more. The Astrakhan region and Dagestan will remain in the zone of irrigation and dry farming, respectively. Kalmykia, according to the RCP 2.6 scenario, remains in the dry farming zone by the end of the century, according to the RCP 4.5 and RCP 8.5 scenarios, it again passes into the irrigation zone. It is obvious that some improvement associated with an increase in the amount of precipitation per year will contribute to the favorable development of natural systems (with a tendency to move from deserts to semi-deserts). At the same time, the conditions for the development of agriculture in most part of the Caspian region will deteriorate.

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