Region-scale projections of future temperature and precipitation trends using CMIP6

Identifying reliable CMIP6 models for regional climate extremes is essential for accurate local impact assessments. This study evaluates temperature and precipitation extremes in Trnava, Slovakia, to determine the most suitable CMIP6 models for urban-scale analysis. Using observed data from one rain gauge (Biely Kostol) and two climatological stations (Kráľová pri Senci and Jaslovské Bohunice) for the period 1991–2024, we assessed maximum daily precipitation (Pmax) and maximum temperature (Tmax). Five Atmosphere–Ocean General Circulation Models (AOGCMs) from the IPCC Sixth Assessment Report (AR6) were selected based on data availability for both the historical period (1980–2014) and future climate projections under three Shared Socioeconomic Pathways (SSP126, SSP245, and SSP585, representing low- to high-impact scenarios). Model performance was evaluated by comparing simulated historical data with observations using the Kling–Gupta Efficiency (KGE) metric. Among the five models, IPSL-CM6A-LR (France) exhibited the highest accuracy for simulating Pmax (KGE: 0.05–0.28 across six station–model comparisons based on yearly and monthly averages), while CNRM-ESM2-1 (France) performed best for Tmax (KGE: 0.53–0.91). The Kráľová pri Senci station consistently yielded the highest KGE values across models. In general, temperature simulations showed greater accuracy than those for precipitation. Further validation for the overlapping period (2015–2024) indicated that SSP245 most closely represents recent climate conditions in Trnava, based on higher R and NSE values and PBIAS values closer to zero for both variables. Figures 1 and 2 show these comparisons at the Kráľová pri Senci station. These results establish a foundation for downscaling future climate extremes in the region, enabling more accurate projections of extreme discharge events and informing urban hydrological planning and climate adaptation strategies.