Time-link from Greenland to Canada

In a collaborative effort glaciologists from the Centre for Ice and Climate and their colleagues from the Geological Survey of Canada have synchronized ice cores from the Agassiz and Renland ice caps to the Greenland Ice Core Chronology 2005 (GICC05). The details of the synchronization has been published in a paper in Journal of Geophysical Research, while the δ¹⁸O data on the new time scales are available on the Centre for Ice and Climate web page (links below).

The synchronization has been carried out using volcanic reference horizons throughout the Holocene, linking the Agassiz ice cores to the NGRIP volcanic record and the Renland ice core to the GRIP volcanic record (see map for drill site locations). The GICC05 time scales for the Agassiz and Renland ice cores are significantly different from the original time scales proposed for the ice cores, a fact that underlines the importance of detailed dating and synchronization efforts within the field of ice core glaciology.

Interestingly the Holocene δ¹⁸O profiles (see figure below) for the Renland and Agassiz ice cores are very similar in their millennial scale trends (except for the A77 core from Agassiz as it is affected by upstream wind scouring). Renland, A79, A84 and A87 δ¹⁸O profiles all show a Holocene climatic optimum some 7500-10500 years ago and a declining trend thereafter. This climatic optimum is much harder to identify in the central Greenland (i.e. GRIP and NGRIP) δ¹⁸O profiles. As all the ice cores have been synchronized this difference cannot be attributed to dating differences.

Links:
Paper in Journal of Geophysical Research: https://doi.org/10.1029/2007JD009143
Data on the Centre for Ice and Climate web page