The so-called "4.2 event" in the central mediterranean and its climatic teleconnections

Abstract

High-resolution isotopic analyses were performed on RL4 flowstone from Renella Cave (Alpi Apuane, central Italy), a speleothem studied previously at low resolution. The new data are discussed together with recently obtained data from Corchia and other localities in the central Mediterranean, to elucidate the possible origin and regional articulation of a climatic event centred at ca. 4.0 ka. This analyses indicates that central to southern Italy between ca 3.8 and 4.3 ka was characterized by drier conditions, whereas in Northern Italy the event seems less expressed or, as within the Alps, marked by cooler and wetter conditions. Several lines of evidence suggest that this event could be characterized by longer summer drought and possibly by little impact on precipitation during winter, even if this aspect needs to be explored in more detail. However, the event is particularly prominent in the northern sector of the African Monsoon domain, which has been robustly linked to southward shifts in the ITCZ; whereas its occurrence is uncertain on northern European latitudes. However, many proxies indicate that there aridification probably started some centuries earlier and culminated at ca. 4.0 ka. Taken as a whole, these data can be used to clarify the regional articulation of this event, but interpretations based on general circulation are still elusive.