Calibrating the ice core paleothermometer using seasonality

High‐resolution oxygen isotope measurements on the Dome Summit South (DSS) ice core from Law Dome, Antarctica, provide a seasonal profile that is sufficiently stable and undistorted by biases in accumulation to permit comparison with measured temperature seasonality. This comparison yields an isotope‐temperature relation with a gradient (dδ/dT) of 0.44±0.02‰/°C and provides a new method for exploring the isotope‐temperature relationship at high‐accumulation sites. If applied to the observed isotope record from the DSS core, which extends through the last glacial and beyond, this calibration suggests that at its coldest the last glaciation was ∼13°C colder than present at this site (after correcting for elevation change). This finding compares with a temperature difference of ∼8°C computed by using the local spatially derived calibration.