Downscaled climate projections for Poland: a verification against observed temperature and precipitation during the reference period 2006–2024

Future climate projections constitute a fundamental source of information for climate change adaptation and long-term strategic planning. Their credibility, however, depends on their ability to realistically reproduce observed climatic conditions during the historical periods. This study evaluates the representativeness of the downscaled climate projections for Poland, prepared within Klimada 2.0 project, by comparing projected and observed temperature (mean, minimum and maximum) and precipitation characteristics over the reference period 2006–2024. The analysis was performed for two emission scenarios (RCP4.5 and RCP8.5) using daily observations from the 53 synoptic stations and CERRA reanalysis. Klimada 2.0 projections reproduced well the observed seasonal cycle and the overall statistical characteristics of temperature and precipitation. The smallest biases were found during autumn, whereas systematic discrepancies occurred during summer, including an underestimation of maximum air temperature and a shift of the precipitation maximum from July in observations to June in the projections. Probability density distributions were generally well represented, although the projections underestimated the variability and the upper tails of the temperature distributions. Spatial analyses revealed relatively small mean biases across most of Poland, while trend analyses indicated that the projections reproduced the long-term climatic tendencies, but underestimated the magnitude of the recent warming observed during 2006–2024. Overall, Klimada 2.0 projections provide a credible basis for the long-term climate impact and adaptation studies in Poland, while highlighting the need for caution when interpreting short-term variability and climate extremes.