Orbital-scale dynamics of Arctic temperature variability across the Pleistocene at Lake El'gygytgyn, Siberia
Abstract
The mid-Pleistocene Transition (MPT) is characterized by changes in the frequency, amplitude, and symmetry of glacial-interglacial climate change, related in part to changing northern hemisphere ice sheet dynamics. Arctic temperature may have played a key role in the MPT as a control on the amount of northern ice. Long continuous records of Arctic temperatures are rare, however, leaving uncertainty about the role and response of Arctic climate during the MPT. Here, sediments from Lake El'gygytgyn in Northeast Russia provide unique constraints on Arctic climate evolution during the late-Pliocene and Pleistocene. We reconstruct growing-season temperature variability at El'gygytgyn from 3.6 Ma to present, resolved at approximately 2000 year sample spacing, using glycerol dialkyl glycerol tetraether biomarkers (GDGTs). Our data suggest that during the MPT, Arctic temperatures were highly variable, but generally increasing. This warming preceded a long-term cooling trend beginning at 800 ka which reached minimum temperatures during Marine isotope Stage 4 at 58 ka. Orbital-scale temperature change exhibits a mixed signature of obliquity and precession that persists through the MPT. The emergence of a quasi-100 kyr cycle following the MPT is surprisingly absent in the GDGT reconstruction, possibly indicating that western Arctic temperature may be somewhat disconnected to ice sheet development over the late Pleistocene or that further assessment of the ice sheet history is needed. Our temperature reconstruction has implications for understanding drivers of Arctic temperature and linkages between temperature and ice sheet behavior at long time scales.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP22B..12D
- Keywords:
-
- 4926 Glacial;
- PALEOCEANOGRAPHY;
- 4930 Greenhouse gases;
- PALEOCEANOGRAPHY;
- 4932 Ice cores;
- PALEOCEANOGRAPHY;
- 4946 Milankovitch theory;
- PALEOCEANOGRAPHY