Reconstructing East Antarctic Temperature and Snowfall Variability from δ15N of N2

East Antarctic ice cores registered variations in local surface temperature and atmospheric composition over the past 800,000 years. However, identifying the precise timing between changes in temperature inferred from the ice and greenhouse gases records is challenging. It assumes that the modern δD–temperature relationship holds over time and there are uncertainties in the age offset between ice and air at a same depth. An alternative approach uses the δ15N of N2, measured in the air-phase, as a proxy for past temperature and snowfall accumulation. Still, a complete understanding of the processes governing δ15N changes is missing. Here we present a δ15N record from the EPICA Dome C ice core covering 800–100 ka. Comparison with a firn densification model driven by δD-based temperature and accumulation reconstructions reveals major discrepancies during glacial intervals at high obliquity. Sensitivity tests with an intermediate complexity climate model reveal that this mismatch is linked to δD not capturing the full variability of the temperature and accumulation. Our finding supports the use of δ15N as a climate tracer to make the link with greenhouse gases concentration and suggests combining δD and δ15N to best reconstruct temperature and accumulation.