Inferring climate variability from replicated Antarctic ice-core water isotope records

Changes in climate variability are as critical to understand as changes in the mean climate, yet remain difficult to quantify from ice cores because single records are strongly affected by local noise arising from depositional, post-depositional, and diffusive processes. As a result, past changes in climate variability cannot be robustly separated from changes in ice-core noise using individual cores alone.
This limitation can be overcome by analysing replicated ice-core records, where the common signal can be interpreted as climate-driven variability. For the first time, such an approach is now feasible for deep Antarctic ice cores through the paired water-isotope records of EPICA Dome C and the new Beyond EPICA Oldest Ice Core (BE-OIC), which together provide a replicated archive extending back 800,000 years.
Here, we present first results from the upper ~ 300 m of the BE-OIC ice core focusing on Holocene variability in stable water isotopes. Using spectral methods, we compare the statistical properties of isotope variability between the two cores to separate common climate variability from local noise and to assess the effective temporal resolution of the preserved signal. These preliminary results provide an initial step towards quantifying multidecadal to millennial-scale climate variability in Antarctic temperature during the Holocene and establish the basis for extending this analysis to earlier interglacial periods with the BE-OIC ice core record.