Piora Oscillation

The Piora Oscillations are two cold periods in the Alpine climate history of the Holocene Epoch. Its dating differs between authors and no consistent modern approach currently exists. The spatial extent of the change is unclear; moreover, it does not show up as a major, or even identifiable, event in hemispheric temperature reconstructions.

The phenomenon is named after the Val Piora (Piora Valley) in Switzerland, where it was first detected.

The water level of Lake Constance in the Alps show a considerable history of variations as reconstructed from sediment and pollen analysis. In 5,375 BP (3,375 BCE) there occurred an abrupt rise in lake level at the archaeological site of Arbon-Bleiche 3, indicating a cooling of the temperatures. This caused an abandonment of this prehistoric lake-shore location.

Two stages of Piora Oscillation, Piora 1, and the later Piora 2 are suggested in recent literature. The Piora 2 oscillation, also called Rootmos 2, refers to the transition between Late Atlantic and Subboreal around 3500 BCE. This period also coincides with the transition between the Pfyn and Horgen cultures in Switzerland.