In the region of the Ladoga Lake catchment basin, we perform data analysis on a set of different modern climate models with different Intergovernmental Panel on Climate Change (IPCC) scenarios in the 20th and 21st centuries; this set includes global models such as ECHAM4/OPYC3 (Max Planck Institute for Meteorology, Germany), HadCM3 (Hadley Centre Coupled Model, England), and RCAO (Rossby Centre Regional Atmosphere-Ocean) models. Two variants of the boundary conditions for these climate models (Rossby Center of Swedish Meteorological and Hydrological Institute, SMHI) are used. We present the results of a diagnosis of the model-predicted near-surface temperature (T), precipitation (P), evaporation (E), and water budget (P-E) in the Ladoga Lake catchment based on their comparison with empirical data in twentieth century. We obtain scenario estimates of the variations of temperature and hydrologic regimes of Ladoga Lake catchment when IPCC IS92a, A2, and B2 scenarios are fulfilled, describing the prognostic growth of anthropogenic emissions of greenhouse gases and aerosol to the atmosphere, and discuss the recommendations for their use.