Abstract: The possibility of a repetition of the limnological catastrophe in the Black Sea is considered. It is shown that, in contrast to the volcanic lakes of Africa Nyos and Manun, where limnological catastrophes occurred in the 1980s, the concentration of dissolved gases in deep waters is significantly less than the saturation value. This eliminates the mechanism of so called “eruption” of carbon dioxide such as gas lift. However, on a smaller scale, significant methane releases are possible during strong eruptions of underwater mud volcanoes. The mechanism for the release of carbon dioxide from the lake into the atmosphere is so similar to a volcanic eruption that mathematical models developed for ordinary volcanoes are used to describe it. In both cases, the rise of erupted masses occurs due to an increase in the buoyancy of the gas-liquid mixture, which carries with it particles of the environment. The formation and growth of gas bubbles at intermediate depths occurs provided that the total partial pressure of all gases inside the bubble exceeds the hydrostatic pressure at a given depth. The article shows that the concentration of dissolved methane in the Black Sea is much less than the saturation level. Due to the relatively low solubility of methane in water, methane bubbles are able to overcome a significant depth range. And as additional components of the gas mixture, together with methane, carbon dioxide and hydrogen sulfide can thus enter the atmosphere. It was concluded that as the water temperature in the Black Sea increases due to climate change, the reserves of methane gas hydrate at the bottom of the sea will begin to decompose, which will also be accompanied by jet gas release. At the same time, methane can escape to the surface from depths of no more than 900 m.

Abstract: In this paper the author discusses such an urgent problem for the environmental safety of the Black Sea region as drought. The frequency of droughts lasting more than three decades in the period from April to August inclusive is considered on the basis of data on monthly precipitation and mean monthly temperatures shown from 1950 to 1999. There were seven two-month droughts and one three-month drought. The frequency of droughts in separate months is calculated. The change over the years of the maximum value of the El Niño index per episode from 1950 to 2023 is analyzed. The connection of two-month droughts with this parameter is noted. Based on the results of the study conducted in this paper, the author comes to conclusions about the regularities in the manifestation of severe droughts in the Black Sea region. In particular, it was concluded that in recent decades, strong manifestations of El Niño recur no more often than after 15 years. This makes it possible to predict episodes with an index value of more than 2.6 not earlier than 2030. It is especially noted that so far the main danger in Crimea is two-month droughts. During the considered 50 years of drought lasting more than six decades in a row in the period from April to August, there were 8 times.

Abstract: The North Crimean Canal is considered as a continuation of the Dnieper River. This makes it possible to analyze its overlap in 2014 as one of the classic problems of transboundary water use associated with partial or complete restriction of flow in the middle or lower reaches of the river. As a similar example, the conflict between Turkey and Syria over the water resources of the Euphrates River is considered. It is shown that such cross-border conflicts are often caused by both economic reasons and arise in connection with a decrease in runoff in some years due to increased aridity of the climate. This article presents game-theoretic models of interaction between the parties and substantiates the need for compensation payments between the countries participating in a cross-border dispute. Based on the results of the analysis carried out in this article, it was concluded that one of the consequences of the possible destruction of the dam of the Kakhovsky reservoir will be the cessation of water supply to the North Crimean Canal. The fact is that in the first section with a length of more than 200 km, water from the reservoir flows into the channel by gravity, so that when the level drops at the water intake point by 16 m, the filling of the channel will stop.

Abstract: This article is dedicated to assessment of the climate changes of the Republic of Crimea over the last few decades. Throughout the analysis, the research utilized data on air temperature changes in the temperate latitudes of Europe by paleoclimatic data, as well as by changes in average temperature of surface waters in the Black Sea according coastal measurements. It is demonstrated that on the background of global warming there are natural manifestations of climatic fluctuations with periods of up to 20 years that relate to warm episodes such as El Niño and North-Atlantic fluctuation. The research methodology is based on the modern theory of global warming, which replaced the Milankovitch cycles concept used until the 1980’s. One of the main consequences of global warming for Russia lies in the significant increase in the frequency of reoccurrence of dangerous hydrometeorological phenomena. Examples of such phenomena include strong floods and heat waves. In a number of regions, the increase in temperature is also accompanied by spread of agents of dangerous diseases – ticks and marsh mosquitoes. However, the most notable damage caused by the climate change in Russia comes from drought.