Evidence for abrupt climatic change in northern Scotland between 3900 and 3500 calendar years BP.

Palaeohydrological and palaeoecological investigations from five locations in northern Scotland reveal a distinct and large-scale shift to wetter climatic conditions which may reflect a major transition in climate from the mid- to late Holocene. Radiocarbon age estimates place this transition between about 3900 and 3500 cal. BP, although the transition appears to have occurred abruptly, possibly over a decadal to century timescale. This event appears to be synchronous with changes inferred for other regions, suggesting that it reflects a continental-scale, or possibly even global-scale, change in climate. Broad correlation with deep-sea sediment records suggests that the transition may reflect colder sea-surface temperatures in the North Atlantic Ocean. [ABSTRACT FROM AUTHOR]