Synchronized Terrestrial- Atmospheric Deglacial Records ~robnd the ~orth Atlantic

On the basis of synchronization of three carbon-14 (I4C)-dated lacustrine sequences from Sweden with tree ring and ice core records; the absolute age of the Younger Dryas-Preboreal climatic shift was determined to be 11,450to 11,390 t 80 years before the present. A 150-year-long cooling in the early Preboreal, associated with rising Ai4C values, is evident in all records and indicates an ocean ventilation change. This cooling is similar to earlier deglacial coolings, and box-model calculations suggest that they all may have been the result of increased freshwater forcing that inhibited the strength of the North Atlantic heat conveyor, although the Younger Dryas may have begun as an anomalous meltwater event. The rapid rnelt~ngof ice sheets during the earliest Holocene must have had an important effect on climate because of the suddenly increased impact of fresh water on the ocean. The tnajor AL4C changes of the Last Tertnination (the deelaciation at the end of