Extra-long interglacial in Northern Hemisphere during MISs 15-13 arising from limited extent of Arctic ice sheets in glacial MIS 14.

Qingzhen Hao,Zhengtang Guo,Frank Oldfield,Luo Wang

doi:10.1038/srep12103

Abstract

Knowledge of the behavior of Northern Hemisphere (NH) ice sheets over the past million years is crucial for understanding the role of orbitally driven insolation changes on glacial/interglacial cycles. Here, based on the demonstrable link between changes in Chinese loess grain-size and NH ice-sheet extent, we use loess grain-size records to confirm that northern ice-sheets were restricted during marine oxygen isotope stage (MIS) 14. Thus, an unusually long NH interglacial climate of over 100 kyr persisted during MISs 15−13, much longer than expected from marine oxygen isotope records. Taking a global view of the paleoclimate records, MIS 14 inception seems to be a response to changes in Antarctic ice-sheets rather than to NH cooling. Orbital configuration in the two Polar regions shows that the onset of MIS 14 was forced by austral insolation changes, rather than by boreal summer insolation, as Milankovitch theory proposes. Our analysis of MIS 14 raises the possibility that southern insolation forcing may have played an important role in the inception of several other glacials. We suggest that the extra-long NH interglacial climate during MISs 15−13 provided favorable conditions for the second major dispersal episode of African hominins into Eurasia.

Highlights

The marine δ 18O records of benthic foraminifera show that the growth and reduction of global ice volume exhibited dominant quasi-periods of 100 kyr since the Mid-Pleistocene transitions of 1200− 800 kyr ago[1,2]
The interglacial soils are characterized by low grain-size fraction >32 μ m (GT32) and high χ fd values, indicating weak East Asian winter monsoon (EAWM) winds and humid conditions
The small extent of Northern Hemisphere ice sheets during marine oxygen isotope stage (MIS) 14 indicated by our study is consistent with the records from northern Atlantic and Eurasian continent

Summary

Introduction

The marine δ 18O records of benthic foraminifera show that the growth and reduction of global ice volume exhibited dominant quasi-periods of 100 kyr since the Mid-Pleistocene transitions of 1200− 800 kyr ago[1,2]. Some records, e.g. biogenic carbonate[4] and ice-rafted-debris (IRD) content[5] in North Atlantic sediments, suggest that MIS 14 was characterized by much less severe glacial conditions, implying that high northern latitudes experienced an extra-long predominantly interglacial style climate during MISs 15–13.

Results

Conclusion