Investigating stable oxygen and carbon isotopic variability in speleothem records over the last millennium using multiple isotope-enabled climate models

Abstract. The incorporation of water isotopologues into the hydrology general circulation models (GCMs) facilitates comparison between modeled and measured proxy data in paleoclimate archives. However, variability drivers isotopologues, as well diversity their representation different models, are not constrained. Improving our understanding this past present climates will help to better constrain future climate change projections decrease range uncertainty. Speleothems a precisely datable terrestrial archives provide well-preserved (semi-)continuous multivariate isotope time series lower latitudes mid-latitudes therefore suited assess on decadal longer timescales. relationships speleothem oxygen carbon isotopes variables influenced by site-specific parameters, GCMs is always straightforward. Here we compare isotopic signatures from Speleothem Isotopes Synthesis Analysis database version 2 (SISALv2) output five water-isotope-enabled (ECHAM5-wiso, GISS-E2-R, iCESM, iHadCM3, isoGSM) over last millennium (850–1850 CE). We systematically evaluate differences commonalities standardized model simulation outputs. goal distinguish climatic for them those isotopes. find strong regional that can partly be attributed surface temperature. At low latitudes, precipitation amount dominant driver stable variability; however, at cave locations agreement temperature higher than variability. While exhibited extreme events coinciding with changes volcanic solar forcing, such fingerprints apparent This may temporal resolution records compared detected. Using spectral analysis, show all underestimate speleothems (albeit varying extents). found no excels analyzed comparisons, although some perform others either mean or Therefore, advise multi-model approach whenever comparing data. Considering karst internal processes, e.g., through isotope-enabled alter play an important role determining most appropriate model. By exploring new ways analyzing relationship isotopes, variability, co-variability across timescales, methods serve baseline studies using, archives, periods.