The dataset comprises discrete water isotopic measurements of the last 27m of the Camp Century ice core that was drilled in 1966. Samples from 5 to 10 g of Camp Century ice were collected at intervals of 40 cm, with a refined sampling resolution in the lower 2 m, where intervals were reduced to approximately 15 cm. The samples were melted at ambient temperature and filtered with 2 µm polyether sulfone filters before analyses to remove the debris. The water isotopes measurements were performed at the Centre for Ice and Climate, Niels Bohr Institute (Copenhagen, Denmark) in 2023 using a cavity ring-down spectrometer. Measurements are referenced to Vienna Standard Mean Ocean Water (VSMOW) using two in-house standards waters, bracketing the sample δ17O, δ18O and δD values (i.e., δ17O (‰) = (17O/16O)sample/(17O/16O)SMOW - 1; δ18O (‰) = (18O/16O)sample/(18O/16O)SMOW - 1; δD (‰) = (D/H)sample/(D/H)SMOW - 1). Standard deviation (SD) was calculated using internal standards during each batch of measurements, as well as by performing triplicate analysis for each sample. For our dataset, we report median 1 SD reproducibility of 0.04 ‰, 0.04 ‰ and 0.35 ‰ for δ18O, δ17O and δD respectively.

The sediment depth is considered to be 1375 according to Herron & Langway (1979). See Biermans et al. (2024) for further discussions about the sediment depth beneath the ice sheet.