Synchronizing ice core records

Several deep ice cores have been drilled from the vast ice sheets of Greenland and Antarctica, and in addition numerous cores have been obtained from many smaller glaciers around the world. All these ice cores contain information on past climate from the region from which they have been retrieved. However, the different records often have their own timescales that are not consistent, so the records can not readily be compared in detail because one cannot know whether observed differences represent real climate differences or differences arising from the different timescales.

It is therefore essential to synchronize the timescales of the different cores in order to compare the climate records in a meaningful way. The synchronization is performed by finding layers in the different cores that have exactly the same age. This is most commonly done by identifying reference horizons or marker beds that can be observed in two or more of the cores. A reference horizon can be a volcanic ash layer in the cores, or any other distinct layer that can be identified in the cores. When the individual records have been linked using a number of reference horizons, we can compare the climate records and detect and interpret differences in past climate. Building a common chronological framework for as many palaeoclimatic data sets as possible is thus essential for understanding past climate dynamics.

The synchronization can be made in many ways, but the idea is the same: identify as many reference horizons as possible in the cores and stretch the timescales of one of more of the ice cores to make align the reference horizons.

Read more about the different approaches to synchronizing ice core records, namely
- synchronization of ice cores using volcanic ash layers
- synchronization of ice cores using cosmogenic isotopes
- synchronization of ice cores using the global CH4 record
- synchronization of ice cores using patterns of peaks in the impurity data