Causes and timing of the 8200yr BP event inferred from the comparison of the GRIP ^1^0Be and the tree ring @D^1^4C record [An article from: Quaternary Science Reviews]

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Description:
We analyse the 8200yr BP cold event by comparing the high-resolution ^1^0Be record from the GRIP ice core from Central Greenland with the well-known tree ring @D^1^4C record. By transferring the absolute dated tree ring chronology to the ice core time scale, we show that the coldest phase in the GRIP record occurred around 8150yr BP. Furthermore, this method allows us to disentangle production and climate effects on ^1^0Be and ^1^4C with important implications for the reconstruction of past solar activity, and changes in the carbon cycle and ^1^0Be transport. We show that, in principle, it is possible to infer changes in ocean circulation by comparing ^1^0Be and ^1^4C records. However, the duration of the 8200yr BP event is too short to assign unambiguously a significant change in atmospheric ^1^4C concentration to changes in the global ocean circulation. Based on the comparison of ^1^0Be with climate records, one could argue that the 8200yr BP cold event is triggered by a change towards lower solar activity. However, this link is questioned by the fact that around this period there are other similar and even stronger changes in solar activity that have no apparent connection to climate changes.