Proxy records of climate from blanket mires: evidence for a Dark Age (1400 BP) climatic deterioration in the British Isles

Pioneer studies of peat stratigraphy in Scandinavia led to division of the Holocene into climatic periods, and though this scheme was later re-evaluated and partly rejected, studies in Denmark and England have demonstrated a link between the stratigraphy of lowland raised mires and past climatic change. In a new study, radiocarbon dating of changes in the degree of humification of peat from blanket mires in the British Isles appears to show a change to wetter conditions around 1400 BP. Five sites, from western Ireland to North Yorkshire, all show this change. These data reinforce other evidence for climatic change in northwest Europe in the mid-first millennium AD. Results demonstrate the potential of blanket peats as a new source of proxy climatic data, covering an intermediate time-scale between recent meteorological records and long-term 'Milankovitch-scale' variations in climate.