Central European temperature variations over the past two millennia recorded in a stalagmite from western Switzerland

Almost all of the Central European temperature reconstructions covering the last two millennia reflect summer rather than mean annual air or cold season temperatures. To address the seasonal bias, we developed highly resolved 2000 year-long calcite isotope (δ¹⁸O) and fluid inclusion water isotope (δ²O and δ¹⁸O) records from a stalagmite from Milandre Cave in the Swiss Jura Mountains. Present-day climate in this region is strongly influenced by westerly air masses, making it an ideal site to record climate variability in the North Atlantic and European realm. Calibration of the Milandre Cave isotope records with historical and observational temperature and isotope data enables us to reconstruct mean annual air temperatures.  Our new temperature reconstruction shows temperature variations of approximately 2°C during the past two millennia, the temperature difference between the warmest decade of the Medieval Climate Anomaly (950–1250 CE) and the coldest decade of the Little Ice Age (1400–1700 CE) is around ~1.7°C. In general, higher central European temperatures were reconstructed in the periods 450–600 CE and 1000–1150 CE, and relatively low temperatures were recorded in the intervals 650–900 CE and 1350–1700 CE. Modelled cold season temperatures for the past millennium compare remarkably well with our reconstruction, and confirm the importance of both solar and internal forcing on Central European temperature.