NALPS19: sub-orbital-scale climate variability recorded in northern Alpine speleothems during the last glacial period

Abstract. Sub-orbital-scale climate variability of the last glacial period provides important insights into the rates at which the climate can change state, the mechanisms that drive such changes, and the leads, lags, and synchronicity occurring across different climate zones. Such short-term climate variability has previously been investigated using δ¹⁸O from speleothems (δ¹⁸O_calc) that grew along the northern rim of the Alps (NALPS), enabling direct chronological comparisons with δ¹⁸O records from Greenland ice cores (δ¹⁸O_ice). In this study, we present NALPS19, which includes a revision of the last glacial NALPS δ¹⁸O_calc chronology over the interval 118.3 to 63.7？ka using 11, newly available, clean, precisely dated stalagmites from five caves. Using only the most reliable and precisely dated records, this period is now 90？% complete and is comprised of 16 stalagmites from seven caves. Where speleothems grew synchronously, the timing of major transitional events in δ¹⁸O_calc between stadials and interstadials (and vice versa) are all in agreement on multi-decadal timescales. Ramp-fitting analysis further reveals that, except for one abrupt change, the timing of δ¹⁸O transitions occurred synchronously within centennial-scale dating uncertainties between the NALPS19 δ¹⁸O_calc record and the Asian monsoon composite speleothem δ¹⁸O_calc record. Due to the millennial-scale uncertainties in the ice core chronologies, a comprehensive comparison with the NALPS19 chronology is difficult. Generally, however, we find that the absolute timing of transitions in the Greenland Ice Core Chronology (GICC) 05_modelext and Antarctic Ice Core Chronology (AICC) 2012 are in agreement on centennial scales. The exception to this is during the