Reconstructed summer temperature variability in the Caucasus since 1613 CE and its relevance for continental-scale climate dynamics

While temperature history has been extensively studied in other parts of the Alpide belt, such as the Pyrenees, the Alps or the Himalaya, the Caucasus region remains underrepresented in paleoclimate research. This gap is evident in large-scale proxy compilations such as the NTREND (tree-rings) or the PAGES2k (multi-proxy) datasets as well as in climate reconstructions based on these compilations. Here, we present a reconstruction of summer temperature variability extending back to 1613 CE, derived from a network of six tree-ring Blue Intensity chronologies collected from upper treelines in the Greater and Lesser Caucasus. The reconstruction explains over 50% of the observed summer temperature variability, captures the signature of global warming, and reveals volcanic forcing signals. However, the network exhibits disagreement regarding the intensity of the Little Ice Age. Our record correlates with temperature reconstructions from Greece and Turkey, but shows an inverse relationship at higher frequencies with Western European temperature records. When combined with reconstructions from northwestern Russia, our data aligns with the East Atlantic/Western Russia (EA/WR) pattern, an atmospheric mode characterized by a temperature dipole over Europe. In its positive phase, this pattern generates cold anomalies over western Russia, the Caucasus and Turkey, accompanied by above-average temperatures in France and parts of Spain. We investigate the temperature dipole associated with the EA/WR pattern during the pre-industrial period across various frequency domains. Our findings offer valuable insights into historical climate dynamics across Europe and serve as a benchmark for evaluating the representation of the EA/WR pattern in climate model simulations.