This article explores the start and end of a period of intensive farming in a karstic region on the west coast of Ireland in the late 3rd and early 2nd millennia BC in relation to episodes of climate change. Human responses to climate change in prehistory have been most frequently studied in regions prone to aridity and drought such as the Near East and the eastern Mediterranean where past climate shifts may have had more extreme effects and are likely to have left strong proxy signals. It is these same regions where early complex societies were located and the collapse or reorganization of these large complex societies can leave similarly strong traces in the archaeological record. In contrast, the present study is focused on the west coast of Ireland, an Atlantic island in a temperate oceanic climate region at a time when the societies living there are best described as small-scale segmentary societies. Geography therefore militated against the most extreme effects of climate change and there were no large complex societies to collapse, nevertheless there is evidence that climate change impacted these societies.