A reconstruction of Holocene climatic changes from peat bogs in north-west Scotland

Continuous palaeoenvironmental sequences from three pear bogs located in north-west Scotland are presented which reveal palaeoclimatic changes during the Holocene. Feat cores were analysed for humification, pollen and a range of other physical and palaeoecological data, and chronologies were constructed by radiocarbon dating. Reconstruction of past changes in bog hydrology formed the basis for palaeoclimatic interpretation. Four regional shifts to wetter bog conditions and two regional shifts to drier conditions are inferred. Best estimated age ranges for the wet shifts span c. 5120 to 5070, 4020 to 3630, 3340 to 3270 and 940 to 800 cal BP, and dry shifts are estimated at c. 4330 to 4120 and 1480 to 1340 cal BP. The most distinctive feature of the record is the oscillation from wetter to drier conditions around 4300 cal BP, followed by a return to wetter conditions after 4000 cal BP. This oscillation was probably caused by climatic changes which also had an influence on the dynamics of Scots pine within the region prior to, and during, its mid-Holocene phase of decline. Later shifts probably also reflect climatic changes, although evidence for human land-use complicates interpretation at c. 3300 cal BP. Potential causes are considered, including changes in the circulation of the North Atlantic Ocean during the mid-Holocene.