Magnitude of isotope/temperature scaling for interpretation of central Antarctic ice cores

Abstract

The conventional interpretation of ice core deuterium and oxygen 18 isotope profiles based on the use of present‐day observations (spatial slope) underestimates glacial‐interglacial surface temperature changes in Central Greenland by up to a factor of two. This likely results from changes in the seasonality of the precipitation due to the particular location of the Greenland ice sheet next to the highly variable northern polar front. In this regard the situation is much simpler for central Antarctica and this should be reflected in the temperature interpretation of ice core isotopic records. With this in mind, we closely examine all relevant information, focusing on the East Antarctic Plateau where both model and empirical isotope‐temperature estimates are available. We point to the fact that correctly accounting for the influence of ocean isotopic change is important when interpreting deuterium profiles from ice cores in this region. The evidence presently available indicates that, unlike for Greenland, the present‐day spatial‐slope can probably be taken as a surrogate of the temporal slope to interpret glacial‐interglacial isotopic changes at sites such as Vostok and EPICA Dome C. Corresponding temperature changes are within −10% to +30% of those obtained from the conventional interpretation based on the use of the spatial slope.