NOAA/WDS Paleoclimatology - Portugal 222,000 Year Speleothem Stable Isotope Data

STUDY NOTES: Stable isotope (d18O and d13C) data from 5 stalagmites collected in 2 Portuguese caves (Buraca Gloriosa and Gruta do Casal da Lebre), covering the past 222 KYr. Note: An error in the age model for stalagmite BG67 was identified after publication of these data. However, since this error does not shift the time series outside the reported uncertainty window, it does not in any way impact the findings or interpretations presented in the manuscript.
ABSTRACT SUPPLIED BY ORIGINATOR: Close coupling of Iberian hydroclimate and North Atlantic sea surface temperature (SST) during recent glacial periods has been identified through the analysis of marine sediment and pollen grains co-deposited on the Portuguese continental margin. While offering precisely correlatable records, these time series have lacked a directly dated, site-specific record of continental Iberian climate spanning multiple glacial cycles as a point of comparison. Here we present a high-resolution, multi-proxy (growth dynamics and d13C, d18O, and d234U values) composite stalagmite record of hydroclimate from two caves in western Portugal across the majority of the last two glacial cycles (~220 ka). At orbital and millennial scales, stalagmite-based proxies for hydroclimate proxies covaried with SST, with elevated d13C, d18O, and d234U values and/or growth hiatuses indicating reduced effective moisture coincident with periods of lowered SST during major ice-rafted debris events, in agreement with changes in palynological reconstructions of continental climate. While in many cases the Portuguese stalagmite record can be scaled to SST, in some intervals the magnitudes of stalagmite isotopic shifts, and possibly hydroclimate, appear to have been somewhat decoupled from SST.