Temperature reconstruction from 10 to 120 kyr b2k from the NGRIP ice core

Abstract. In order to reconstruct Greenland NGRIP temperature, measurements of δ15N from the beginning of the Holocene to Dansgaard–Oeschger (DO) event 8 have been performed. Together with previously measured and mostly published δ15N data, we are now able to present for the first time a NGRIP temperature reconstruction for the whole last glacial period (beginning of the Holocene back to 120 kyr) including every DO event based on δ15N isotope measurements using a firn densification and heat diffusion model. The detected temperature rises at DO events range from 5 °C (DO 25) up to 16.5 °C (DO 11), ± 3 °C. To bring measured and modelled data into agreement, we had to reduce the accumulation rate given by the ss09sea06bm time scale in some periods significantly, especially during the last glacial maximum (LGM). A comparison between reconstructed temperature and δ18Oice data confirms that the isotopic composition of the stadial was strongly influenced by seasonality. We continuously calculated α (δ18Oice to temperature sensitivity) on a 10 kyr running time window. α variations show an anticorrelation with obliquity, in agreement with a simple Rayleigh distillation model, and moreover seem to be influenced by Northern Hemisphere ice sheet volume.