The 520-Year Temperature Record of a 100 M Core from the Ronne Ice Shelf, Antarctica

Abstract

Evidence for climatic changes during the last 520 years was inferred from 18O content of a 100 m ice core from the Ronne Ice Shelf, Antarctica. The core was stratigraphically dated using seasonal variations of l8O content. The mean 18O content of the annual layers calculated on the basis of this dating decreases with depth z according to δ18O (‰) = −27.3 - 0.049z (m) and reflects first of all the decrease of the 18O content of the near-surface layers in the catchment area of the core from the drilling site 250 km to the south. This effect was corrected by assuming a linear decrease of the 18O content of the near-surface layers with increasing distance from the drilling site. Corrected δ18O values show a large scatter from year-to-year due to the local variability. The smoothed isotopic record displays variations in different time scales, which are caused most probably by climatological induced temperature variations. The gradient of 18O content with the 10 m firn temperature of 1.15‰/K found in the middle part of the Filchner-Ronne Ice Shelf was used to transfer the 18O series to a temperature record.