Last august I posted on the discovery of a significant solar proton event which was precisely dated by tree ring records to within a couple of years of 7176 BC. To my awareness, this is the earliest date in history we have for any event this tightly fixed. At the time I read the paper, I thought, “it would be great if they went back to the ice cores, which gave previous hints telling ring researchers where to focus their efforts, to really establish another calibration point there”.
Well a team did just that, and last month a confirming paper was published with detailed analysis of ice entrapped 10Be and 36Cl, yielding information on the frequency and severity of the disruptive potential of solar flares…
…we present 10Be and 36Cl data measured in ice cores from Greenland and Antarctica. The data consistently show one of the largest 10Be and 36Cl production peaks detected so far, most likely produced by an extreme SEP event that hit Earth 9125 years BP (before present, i.e., before 1950 CE), i.e., 7176 BCE. Using the 36Cl/10Be ratio, we demonstrate that this event was characterized by a very hard energy spectrum and was possibly up to two orders of magnitude larger than any SEP event during the instrumental period.
Late quaternary geochronology gains a new and valuable reference point…
The identification of a synchronous peak in 10Be from ice cores and in 14C from tree rings provides a valuable global time-marker. First, the present work confirms the validity of the transfer function proposed by Adolphi and Muscheler, i.e., the synchronization of the GICC05 and IntCal time-scales based on common centennial-scale variations in the production rates of 10Be and 14C in ice cores and tree rings leading to an adjustment of −54 years (±6 years) to the GICC05 time scale. Secondly, the independent discovery of a peak in radiocarbon and 10Be allows the reduction of the time-scale synchronization uncertainty around that time to about one year connected to the sampling uncertainty and the 10Be residence time. Therefore, our results support the 54 years offset but reduce the uncertainty for the match between the Greenland ice core time scale to the absolute dendrochronologically determined IntCal 14C time scale from an estimated 6 years to only one year around 9125 years BP.
GICC05 stands for Greenland Ice Core Chronology 2005, which is a multicore calibration.
The prior discovery paper found 14C spikes in tree rings corresponding to 7176 BC in chronologies from diverse locations of Switzerland, Germany, Ireland, Russia, and the USA. It is absurd to suggest that these records could be synchronized globally if false rings, which are rare and due to local seasonal weather when they do occur, were throwing off the count. A synchronization date over nine thousand years ago is a tremendous verification that hemispherically separated tree ring records are reliable. Now that synchronization is independently firmed up for ice core annual layers as well, further discrediting the YEC snow job interpretation of weather bomb events and validating that the ice sheets must have formed over hundreds of thousands of years.