Evidence for a bi-partition of the Younger Dryas Stadial in East Asia associated with inversed climate characteristics compared to Europe

Gordon Schlolaut,Richard A Staff,Michael H Marshall,Charlotte L Bryant,Henry F Lamb,Pavel E Tarasov,Jonathan J Tyler,Achim Brauer,Christopher Bronk Ramsey,Takeshi Nakagawa

doi:10.1038/srep44983

Abstract

The Younger Dryas Stadial (YDS) was an episode of northern hemispheric cooling which occurred within the Last Glacial Interglacial Transition (LGIT). A major driver for the YDS climate was a weakening of the Atlantic Meridional Overturning Circulation (AMOC). It has been inferred that the AMOC began to strengthen mid-YDS, producing a bipartite structure of the YDS in records from continental Europe. These records imply that the polar front and westerlies shifted northward, producing a warmer second phase of the YDS in Europe. Here we present multi-proxy data from the sediments of Lake Suigetsu (Japan), as evidence that a related bi-partition of the YDS also occurred in East Asia. Besides showing for the first time that the bi-partition was not limited to the North Atlantic/European region, the data also imply a climatic dipole between Europe and East Asia since the cold-warm characteristics are reversed at Lake Suigetsu. We suggest that changes in eastward moisture transport from the North Atlantic are the primary mechanism by which the teleconnection can be explained.

Highlights

The Younger Dryas Stadial (YDS) occurred between ≈12.8 and ≈11.6 ka BP and while the exact mechanisms behind the YDS remain enigmatic[1,2,3], it is known that a weakening of the Atlantic Meridional Overturning Circulation (AMOC) occurred during this interval[4], which was a strong driver for the YDS climate
The age model is based on a dual-method varve count[15,16], further constrained by speleothem derived U-Th ages that were modelled onto the varve chronology using the Δ14C signals of the respective archives as a linkage[13]
The results of the pollen analysis were translated into estimates of seasonal and annual temperature and precipitation using the modern analogue technique20. δ15N measurements on bulk sediment were made at low resolution (≈15 cm for the whole 73 m SG06 profile)[21]

Summary

Results and Discussion

All of the employed techniques (microfacies, μXRF, pollen, and bulk isotope analysis) reveal a two-phase character of the YDS at Lake Suigetsu (Fig. 2). The pollen-based temperature reconstruction shows declining temperatures with a high variability in the first part of the YDS and stable and cool conditions during the second part (Fig. 2a), with no distinguishable difference in character between seasonal and annual reconstructions (Supplementary Fig. S2) It has been shown (for orbital time scales) that temperature changes in Japan are strongly tied to glacial forcing[22]. The pollen-based precipitation reconstruction shows that winter (October to March) precipitation was enhanced during the YDS, with a further increase occurring in the second phase of the YDS (Fig. 2b), which resulted in a clear increase in the mean annual precipitation (Fig. S2) These changes can be directly translated into a strengthening of the EAWM12 and

Encyonema layer frequency

Methods

Author Contributions

Additional Information