Integrity and Interpretation of the Beyond-EPICA Oldest Ice core isotope record between 1 and 1.5 Mio years

Which parts of the oldest ice-core water-isotope record can be trusted as a climate archive, and at what temporal resolution is the climatic information preserved?

The water-isotope record from the Beyond EPICA ice core represents the oldest continuous Antarctic ice-core climate archive, extending back to ~1.5 million years and uniquely covering the Mid-Pleistocene Transition. However, the deepest sections of ice cores are commonly affected by ice-flow-induced deformation that can distort the original stratigraphy. In addition, local depositional and post-depositional processes, as well as isotopic diffusion, progressively alter and smooth the climatic signal preserved in water isotopes.

Here, we assess the integrity and effective resolution of the Beyond EPICA water-isotope record by analysing its variability and comparing statistical properties of the measured signal with expectations derived from younger interglacials, other paleoclimate archives, and theoretical estimates of isotopic diffusion. This analysis is complemented by Dielectric Profiling (DEP) and optical line-scan data, which provide independent constraints on stratigraphic continuity and ice-core integrity. Together, these approaches allow us to begin assessing which parts of the Beyond EPICA record between 1.0 and 1.5 million years retain coherent climatic information, and to place first-order constraints on its temporal resolution.