Younger Dryas Abrupt Cooling Event
…we argue that this is indeed supported by three observations: (1) the abrupt and strong increase in residual 14C at the start of the Younger Dryas that seems to be too sharp to be caused by ocean circulation changes alone, (2) the Younger Dryas being part of an approxl. 2500 year quasi-cycle also found in the 14C record that is supposedly of solar origin, (3) the registration of the Younger Dryas in geological records in the tropics and the mid-latitudes of the Southern Hemisphere.
The Younger Dryas (YD, 12.9}11.6 ka cal BP, Alley et al., 1993) was a cold event that interrupted the general warming trend during the last deglaciation. The YD was not unique, as it represents the last of a number of events during the Late Pleistocene, all characterised by rapid and intensive cooling in the North Atlantic region (e.g., Bond et al., 1993; Anderson, 1997).
Moreover, the YD seems to be part of a millennial-scale cycle of cool climatic events that extends into the Holocene (Denton and KarleHn, 1973; Harvey, 1980; Magny and Ru!aldi, 1995; O'Brien et al., 1995; Bond et al., 1997). Based on analysis of the 14C record from tree rings, Stuiver and Braziunas (1993) suggested that solar variability could be an important factor affecting climate variations during the Holocene (see also Magny, 1993, 1995a),