This is still ‘work in progress’.
A graph posted at the blog-site “Climate Etc.” in the series ‘Nature Unbound – IX’ related to the Eddy cycle. Like in similar cases before, this graph was compared chronologically with graphs in the ‘Searching Evidence’ that relate to the history of megalithic calendars, a primary study subject at this site.
It was with some surprise to find consecutive chronological correlations from the Eddy cycle, to main events as were discerned from calendar design evolution and from other proxies that have showed similar correlations. These correlations point to a series of events of a cataclysmic and destructive nature between 6000 bce and 2000 bce.
No answers are available. It is also an open question of what was the driver; whether the Eddy cycle is a characteristic of the driver mechanism of natural tectonic events, or simply a signature from those events.
Some explanations on dates and respective events:
2345bce: obliquity change ~14.5 to ~24deg. First identified by JF Dodwell; evidenced by alteration of dimensions of Mnajdra south calendar. Appears in Temp anomaly (Wiki) as polar temp increase but equatorial decrease. Plus in other proxies (incl tree ring). Switch from cold to warm in Eddy cycle for high latitudes, opposite for in-between tropics.
4375bce and 6200bce: similar to 2345. First identified in Temp anomaly, later in other proxies. 4375 appeared in tree rings as ‘unexplained’, yet correlated.
3195bce (and 5200): calendar evolution shows two abrupt changes in orientation, an early one, and another near/pre 2900bce. 3195bce noted in tree rings (a precise/narrow date). ~3200 is a period known for climate (Piora oscillation) and civilisation upheaval. There appeared in proxy as an abrupt change in ice rafting, together with an identical event at ~5200. Both are a geological tectonic micro-plate rotation. Evidence is now building up. See Ref-1
3550bce (~5600?): Calendar dimensions show alternate obliquity increase/decrease. The decrease point is difficult to identify time-wise, except for a peak in proxy C/N ice-cap Iceland (see pic). An identical at 5600 corresponds to Eddy peak, indicating warm period but abrupt change towards cooling. Agrees with dimensional change in two adjacent calendars with same orientation (see Ggantija N).
Ref-1: D’Andrea et al “Glacier response to North Atlantic climate variability during the Holocene”
Additional data: Comparing on same chronological datum various sources:
polar and equatorial ice proxies; Eddy cycle; Ice rafting; archaeological evidence (partially dated)
To note the events at ~5200bce and ~3200bce.