High summer temperatures in Central Europe during the Bølling period (∼14.6-14.0 cal ka BP) inferred from plant macrofossils using a novel European calibration dataset

Quantitative reconstruction of past temperatures is essential for understanding regional climate variability, and plant macrofossils provide valuable paleoclimatic records due to their sensitivity to summer conditions. However, no plant macrofossil-based quantitative summer temperature reconstructions have been available from Central Europe, limiting our understanding of regional Lateglacial climate dynamics. Therefore, we present the first macrofossil-based quantitative reconstruction of summer temperatures from Central Europe, utilizing sedimentary sequences from the Santovka-PB and Hanšpíle sites (northern Pannonian Basin, SW Slovakia) and a newly compiled, comprehensive pan-European aquatic and wetland plant calibration dataset. Using probabilistic Climate REconstruction SofTware (CREST) and regression-based Weighted Averaging (WA) and Weighted Averaging Partial Least Squares (WA-PLS) approaches, we reconstructed mean July temperatures (T July ) from the Late Pleniglacial to mid-Holocene. Both numerical frameworks yielded highly consistent results, demonstrating the robustness of the reconstruction across different calibration techniques. Our results show that regional warming started before the Bølling interstadial, with pre-Bølling T July of 16–17 °C around ∼16.2 cal ka BP, followed by extreme summer warmth during the Bølling (14.6–14.0 cal ka BP; ∼20 °C) and marked cooling during the Older Dryas (∼14.0–13.9 cal ka BP). Aquatic and wetland plants, sensitive to summer insolation in shallow-water environments, track rapid temperature shifts more reliably than other paleoecological proxies, though local habitat transitions can mask these signals. This study demonstrates that macrofossil-based reconstructions, when combined with carefully curated calibration datasets, offer a reliable framework for capturing regional Lateglacial climate variability and summer temperature extremes.