Was there a MIS 6/5e "Younger Dryas"

  • Broecker No, other's Yes
  • why did MIS 6/5e Younger Dryas "clovis drought" not cause N.Amer. Megafaunal extinctions?
    • charcoal (fire) fluctuations in 6/5e vs. 2/1?
    • Sporormiella (megafaunal) fluctuations in 6/5e vs. 2/1?
  • MIS 6/5e "Younger Dryas" different from MIS 2/1 in N.Amer. because humans were present ?

Broecker, W.S. 2003. Does the Trigger for Abrupt Climate Change Reside in the Ocean or in the Atmosphere? Science 300: 1519-1722.

"Because there is no evidence that a similar millennium-long cold episode punctuated earlier glacial terminations, the YD appears to be a one-time event made possible by a quirk in the relation between the glacially excavated topography and the position of the retreating ice front."

Wu, G., Pan, B., Guan, Q., Liu, Z., Li, J. 2002. Loess record of climatic changes during MIS5 in the Hexi Corridor, northwest China. Quaternary International 97-98: 167-172.

"Evidence from both terrestrial and marine data suggest that there was a "Younger Dryas" type climatic oscillation (Kattegat stadial) at the MIS6/5e transition (Seidenkrantz et al., 1996). Coral reef terraces at Huon Peninsula, west Pacific Ocean, also record rapid fluctuations in sea level during the penultimate deglaciation, which may include a Younger Dryas-type event (Esat et al., 1999). These results indicate that the penultimate deglaciation is a complex process."

Esat, T.M., McCulloch, M.T., Chappell, J., Pillans, B., Omura, A., 1999. Rapid fluctuation in sea level recorded at Huon Peninsula during the penultimate deglaciation. Science 283, 197-201.

Seidenkrantz, M-S., Bornmalm, L., Johnsen, S.J., Knudsen, K.L., Kuijpers, A., Lauritzen, S-E., Leroy, S.A.G., Mergeai, I., Schweger, C., Vliet-Lanoe, B.V., 1996. Two-step deglaciation at the Oxygen Isotope Stage 6/5e transition: the zeifen-kattegat climate oscillation. Quaternary Science Reviews 15, 63-75.