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

Evidence for climatic changes during the last 520 years was inferred from 18 O content of a 100 m ice core from the Ronne Ice Shelf, Antarctica. The core was stratigraphically dated using seasonal variations of l8 O content. The mean 18 O content of the annual layers calculated on the basis of this dating decreases with depth z according to δ 18 O (‰) = −27.3 - 0.049 z (m) and reflects first of all the decrease of the 18 O 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 18 O content of the near-surface layers with increasing distance from the drilling site. Corrected δ 18 O 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 18 O 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 18 O series to a temperature record.