Reconstruction of the paleoaccumulation rate of central Greenland during the last 75 kyr using the cosmogenic radionuclides 36Cl and 10Be and geomagnetic field intensity data

Abstract

The accumulation rate is one of the most fundamental climate parameters to be derived from ice cores. In addition to its climatic importance, the accumulation rate provides a crucial constraint on depth–age scales where annual layer counting is not possible. So far, there is no consistent picture of the accumulation rate for the last ice age in central Greenland. Therefore, we have derived the accumulation rate for the time interval of about 3–75 kyr BP by applying a method based on the cosmogenic radionuclides 36Cl and 10Be in the Summit ice cores and on geomagnetic field data. The main difference between our approach and the methods applied previously is that the accumulation rate based on 36Cl and 10Be does not depend on an ice flow model estimating the original thickness of annual layers. Our new reconstruction agrees well with the accumulation rate published by Johnsen et al. [Tellus 47B (1995) 624–629] until 60 kyr BP and differs significantly from that of Cuffey and Clow [J. Geophys. Res. 102 (1997) 26383–26393].