Iron Age Cold Epoch
The Iron Age Cold Epoch was a period of unusually cold climate in the North Atlantic region, lasting from about 900 BC to about 300 BC, with an especially cold wave in 450 BC during the expansion of ancient Greece. It was followed by the Roman Warm Period.
Gill Plunkett and Graeme T. Swindles of Queen's University Belfast used volcanic ash layers and radiocarbon dating to constrain the start of Iron Age climate deterioration in Ireland to 750 BC.