Climate change impact on the freshwater balance of quasi-closed lagoons in the North-Western Black Sea coast

We studied the impact of regional climate changes that have occurred and are expected in the near future on the freshwater balance of quasi-closed lagoons in the North-Western Black Sea region. These lagoons do not have a permanent connection with the sea but are episodically connected to it by artificial channels, straits, or other hydraulic facilities. We used the value of the deficit in their annual freshwater balance as an indicator of vulnerability to climate change for each lagoon. The changes in the multi-year averages of climatic parameters in the North-Western Black Sea region, which determine the components of the water balance and its annual deficit in lagoons, were assessed by observations at hydrometeorological sites and outcomes of the EURO-CORDEX Project for the RCP4.5 and RCP8.5 scenarios. We have found that regional climate changes are resulting in the increasing deficit of annual freshwater balance for all quasi-closed lagoons in the North-Western Black Sea region. Also, climate change can result in excessive shallowing, salinization, and even the complete disappearance of some lagoons due to the lack of or insufficient water exchange with the sea.