Documentary Evidence of Past Extreme Weather and Climate Events in Poland in the 11th–15th Centuries

Extreme weather and climate events (WCs)—including severe frosts, heatwaves, cold and warm waves, and anomalous seasonal conditions—pose significant threats to natural ecosystems and human societies. While numerous reconstructions of average climate variables exist for Poland, detailed analyses of extreme events using documentary evidence remain comparatively scarce. In the context of ongoing global warming, understanding historical extremes is crucial for assessing the natural range of climate variability and anticipating future risks.

In this study, we compile and analyze archival records of extreme cold and warm episodes in Poland from the 11th to the 15th centuries. Three types of documentary sources were utilized: handwritten and unpublished records, published documents, and secondary literature. The database includes detailed information on each event’s occurrence (location/region, time, duration, and intensity index), as well as the exact textual content of the original weather note, the source name, and an evaluation of its quality. Using this dataset, we examine the spatiotemporal distribution, duration, intensity, and frequency of the studied extreme events.

Preliminary results indicate that severe frosts, snowstorms, and ice formation on lakes, rivers, and the Baltic Sea were frequently reported, with an increasing trend toward the later centuries. Similarly, warm extremes (heat and warm waves), though less frequently recorded than cold-related events, became more notable toward the end of the study period. A key factor contributing to this increase is the growing availability of historical sources over time. Our findings also highlight distinct periods of heightened climatic extremes, indicating that extreme events were not uniformly distributed across the studied centuries.

Moreover, a comparative assessment with modern extremes suggests that historical records provide valuable insights into the evolution of WCs under current global warming trends. This research not only enhances our understanding of past climate extremes but also offers a long-term perspective essential for forecasting future climatic hazards.

This work was supported by the National Science Centre, Poland, project No. 2020/37/B/ST10/00710.