The Mid-Pleistocene Transition (MPT) is a widely recognized global climate shift occurring between approximately 1250 and 700ka. At this time, Earth's climate underwent a major transition from dominant 40kyr glacial-interglacial cycles to quasi-100kyr cycles. The cause of the MPT remains a puzzling aspect of Pleistocene climate. Presently, there are few, if any, continuous MPT records from the Arctic, yet understanding the role and response of the high latitudes to the MPT is required to better evaluate the causes of this climatic shift. Here, we present new continental biomarker records of temperature and vegetation spanning 1142 to 752ka from Lake El'gygytgyn (Far East Russia). We reconstruct warm-season temperature variations across the MPT based on branched glycerol dialkyl glycerol tetraethers (brGDGTs). The new Arctic temperature record does not display an overall cooling trend during the MPT but does exhibit strong glacial-interglacial cyclicity. Spectral analysis demonstrates persistent obliquity and precession pacing over the study interval and reveals substantial sub-orbital temperature variations at 1/4900ka during the first "skipped"interglacial. Interestingly, Marine Isotope Stage (MIS) 31, which is widely recognized as a particularly warm interglacial, does not exhibit exceptional warmth in the Lake El'gygytgyn brGDGT record. Instead, we find that MIS 29, 27, and 21 were as warm or warmer than MIS 31. In particular, MIS 21 (1/4870 to 820ka) stands out as an especially warm and long interglacial in the continental Arctic while MIS 25 is a notably cold interglacial. Throughout the MPT, Lake El'gygytgyn pollen data exhibit a long-term drying trend, with a shift to an increasingly open landscape noted after around 900ka (Zhao et al., 2018), which is also reflected in our higher plant leaf wax (n-alkane) distributions. Although the mechanisms driving the MPT remain a matter of debate, our new climate records from the continental Arctic exhibit some similarities to changes noted around the North Pacific region. Overall, the new organic geochemical data from Lake El'gygytgyn contribute to expanding our knowledge of the high-latitude response to the MPT.
Bibliographical noteFunding Information:
Acknowledgements. We thank Martin Melles, Volker Wen-nrich, and numerous other international collaborators of the Lake El’gygytgyn Drilling Project. We also thank Anders Noren, Kristina Brady, and the staff at LacCore for their assistance and support with numerous large sample requests, as well as John Sweeney and Jeff Salacup at University of Massachusetts for technical support. This research was partially supported by a University of Massachusetts Commonwealth Honors College undergraduate research grant to Kurt R. Lindberg. We thank the editor and anonymous reviewers for insightful comments that improved the manuscript.
Financial support. This research has been supported by the National Science Foundation (grant no. 1204087).
© 2022 Kurt R. Lindberg et al.
Continental Scientific Drilling Facility tags