An annual-resolution stable isotope record from Swiss subfossil pine trees growing in the late Glacial

Previous studies have suggested that the Late Glacial period (LG; ∼14 600–11 700 cal BP) was characterised by abrupt and extreme climate variability over the European sector of the North Atlantic. The limited number of precisely dated, high-resolution proxy records, however, restricts our understanding of climate dynamics through the LG. Here, we present the first annually-resolved tree-cellulose stable oxygen and carbon isotope chronology (δ¹⁸O_tree, δ¹³C_tree) covering the LG between ∼14 050 and 12 795 cal BP, generated from a Swiss pine trees (P. sylvestris; 27 trees, 1255 years). Comparisons of δ¹⁸O_tree with regional lake and ice core δ¹⁸O records reveal that LG climatic changes over the North Atlantic (as recorded by Greenland Stadials and Inter-Stadials) were not all experienced to the same degree in the Swiss trees. Possible explanations include: (1) LG climate oscillations may be less extreme during the summer in Switzerland, (2) tree-ring δ¹⁸O may capture local precipitation and humidity changes and/or (3) decayed cellulose and various micro-site conditions may overprint large-scale temperature trends found in other δ¹⁸O records. Despite these challenges, our study emphasises the potential to investigate hydroclimate conditions using subfossil pine stable isotopes.