Millennial-scale temperature variability during Marine Isotope Stages 19 and 31 in the continental Arctic

Wednesday, 17 December 2014
Greg de Wet1, Isla S. Castañeda1, Julie Brigham-Grette1, Jeff M Salacup2, Benjamin Andrew Keisling3 and M. Helen Habicht3, (1)University of Massachusetts Amherst, Amherst, MA, United States, (2)Brown University, Providence, RI, United States, (3)UMass Amherst-Geosciences, Amherst, MA, United States
In light of predicted climate change, high-resolution paleoclimate records are essential to accurately contextualize future warming. The Arctic region in particular is currently lacking terrestrial paleoclimate reconstructions that extend beyond the last glacial period. A sediment core from Lake El’gygytgyn (Russia) provides a continuous record of Arctic climate spanning the past 3.6 Ma. Here we utilize molecular organic proxies to create millennial-scale paleotemperature reconstructions through Marine Isotope Stages (MIS) 19 and 31, two interglacial periods considered to be good analogs for the current interglacial and future climate change, respectively. MIS 31 has been previously identified a “super interglacial” period at Lake El’gygytgyn whereas MIS 19 provides an analog for the current MIS 1 interglacial, without anthropogenic influences, due to similar orbital forcing. Our paleotemperature reconstructions, based on the branched glycerol dialkyl glycerol tetraether (brGDGT) paleothermometer, demonstrate that Lake El’gygytgyn sediments capture glacial-interglacial climate variability noted in global climate records (Figure 1) and suggests close ties to Antarctic climate. We find that MIS 31 was the warmest interglacial period of the past ~ 1 Ma, in agreement with pollen-derived temperature estimates. Our cm-scale brGDGT temperature reconstruction, with an average time step of <500 years, to the best of our knowledge provides the highest resolution Arctic paleoclimate record of this “super interglacial” and reveals variability hitherto unobserved by lower resolution marine records. Our results are placed in context of paleotemperature reconstructions over the period of MIS 19-35. Remarkably, multiple proxies display a number of abrupt and short-lived temperature fluctuations of ca. 3-5°C occurring within MIS 19 and 31, as well as within other previous interglacials at Lake El’gygytgyn. We examine our results in the context of other biomarker records, existing paleolimnological data, and modeling studies of Lake El’gygytgyn, as well as other high latitude records, to better understand the nature of interglacial climate during these two important intervals in the Arctic.