The ‘4.2 kyr event’ in the British Isles: evidence for an abrupt climate event in the North Atlantic?

Abstract

Palaeoenvironmental and archaeological data from several regions around the world show evidence of a multi-centennial climatic event occurring approximately 4.2 cal. kyr BP. Abrupt climate change events (ACCs) in the early-Holocene were dominated by meltwater pulse events associated with the final stages of deglaciation, a mechanism unlikely to have driven subsequent ACCs in the mid- and late-Holocene. A study of the ‘4.2 kyr event’ therefore provides an opportunity to study ACCs in the context of comparable environmental conditions to those of the modern day, thus providing valuable lessons for the future. Whilst the climatic change and/or impact of the 4.2 kyr event is clear in certain regions (such as southwest Asia), more work must be done to disentangle the timing and magnitude of change at this time in other regions, including northwest Europe. A more comprehensive reconstruction of the event’s spatial and temporal variability will help determine the likely drivers of this event. Here we present the results of a multi-proxy examination of a peat sequence from Sluggan Moss, Northern Ireland. A range of palaeohydrological proxy analyses have been undertaken, including: humification, plant macrofossil and testate amoebae analyses. Furthermore, stable isotopic analysis (13C and 18O) of Sphagnum ?-cellulose presents an opportunity to examine changes in atmospheric circulation across the 4.2 kyr event. The chronological resolution on the sequence is exceptionally high, providing an excellent opportunity to determine the synchroneity of the climatic signal across the North Atlantic region around 4.2 cal. kyr BP.