The Rostov Region is one of the key agricultural regions of Russia, and changes in its climate towards aridity are causing concern for the country's food potential. To assess the dynamics of aridization and build scenarios for the coming decades, SFedU scientists used ERA-5 reanalysis data for the period from 1951 to 2024 and three models of the CMIP6 climate project: MPI-ESM1-2-HR, CanESM5 and BCC-CSM2-MR.

Global climate reanalysis is a reconstructed data set on the state of the atmosphere, ocean, and land, created by combining historical observations with modern numerical climate models. ERA5 is the fifth generation of such reanalysis from the European Center for Medium—term Weather Forecasts. Their data may differ from actual observations at weather stations, so for specific tasks they require verification with ground observations, which is what the SFedU is doing.

Senior Researcher at the Department of Oceanology at the SFedU Institute of Earth Sciences, participant in the SFedU postdoc program under the Priority 2030 Development Program (national project "Science and Universities") Denis Krivoguz said that the main indicator was the de Martonne aridity index, which takes into account the ratio of precipitation and temperature. Lower index values indicate more arid conditions.

"The analysis of ERA5 data shows a pronounced cyclicity in the region's climate change. In the 1950s, the region was characterized by arid conditions with minimal aridity index values. In the 1960s and 1980s, there was a steady increase in the de Marton index and a transition to wetter conditions, especially in the western part of the region. The wettest years were the 1990s and 2000s, when the index reached its maximum values for the entire observation period. However, in the last two decades, the intensification of aridization has begun again, which is especially noticeable in the southeastern regions," Denis Krivoguz said.

Spatial analysis has shown that a stable meridional gradient remains throughout the entire observation period: the least arid conditions are typical for the northwestern regions of the Rostov region, while the southeastern territories of the region experience the highest levels of aridity.

Making a forecast for the future, we can say that all three climate models (MPI-ESM1-2-HR, CanESM5, BCC-CSM2-MR) demonstrate further warming by 1.5-3°C by 2054. The models show various scenarios for moisture changes: from stabilization to intensification of aridization with a potential decrease in the de Marton index by 15-25%.

"Our study shows that 80% of the territory of the Rostov region remains in a zone of relatively low climatic risk, where the traditional structure of crops can be preserved with minimal adaptation measures. For these territories, corn, soybeans and winter wheat should remain the basis of crop rotation, with the gradual addition of 10-15% of drought–resistant crops – sorghum and chickpeas — as insurance," Denis Krivoguz emphasized.

At the same time, 20% of the territory of the Rostov region, namely the areas in the southeast - Zavetinsky, Zimovnikovsky, Orlovsky and Remontnensky, where aridization is most pronounced, require radical measures: over the next 3-5 years, it would be reasonable to transfer 50-70% of grain areas to drought—resistant crops, making sorghum and chickpeas the basis of local agriculture. because they are optimally adapted to conditions with an aridity index of 25-40 units.

"At the same time, it is critically important to implement a set of water management measures, including the development of efficient irrigation systems due to increased evaporation, the revision of water use strategies taking into account the annual decrease in the level of the Tsimlyansk reservoir by 1.2 meters, as well as the development of mechanisms for regulating competition for water resources between agriculture and industry. Such measures will minimize the negative effects of climate change and ensure the sustainable development of the agro—industrial complex in the region," Denis Krivoguz added.

Rising temperatures will increase evaporation and evapotranspiration, which, combined with uneven precipitation distribution, will increase dependence on irrigation. This will require a comprehensive review of water resources management strategies, especially taking into account the steady decline in the volume of the Tsimlyansk reservoir.