CLIMATIC SIGNIFICANCE OF THE SEDIMENTARY RECORD FROM LAKE EL’GYGYTGYN: A 3.6 MILLION YEAR LONG ARCHIVE OF ARCTIC CHANGE

The record from Lake El’gygytgyn, NE arctic Russia provides the first complete record of Pliocene climate change from the terrestrial Arctic. Lake El’gygytgyn evidence shows 3.6-3.4 Ma ago summer temperatures were ~8oC warmer than today and precipitation 4X higher when pCO2 was ~400 ppm. Sedimentation rates were as high as 45cm/1000 yrs. Multiproxy evidence suggests extreme warmth and polar amplification during the middle Pliocene with low amplitude changes between cold and warm Milankovitch cycles consistent with the LR stack. Sudden stepped cooling events during the Pliocene-Pleistocene transition recorded at Lake E are consistent with marine proxies from the North Pacific and North Atlantic suggesting that polar amplification was recorded across the northern hemisphere in both marine and Arctic terrestrial environments. The first evidence of sedimentation styles similar to full “glacial conditions found in the late Pleistocene shows up at 2.6 Ma but is not consistently cyclic until after 1.8 Ma. Summers warmer than present Arctic persisted until ~2.2 Ma, after the gradual onset of Northern Hemispheric glaciation. Our data are consistent with sea-level records and marine proxies published by others indicating that Arctic cooling was really insufficient to support large-scale ice sheets until the early Pleistocene. Vegetation proxies and sedimentation rates both suggest a major change in precipitation at about 2.72 Ma possibly connected to the onset of perennial Arctic sea ice. Glacial/interglacial sedimentary cycles of the last 2.6 Myrs are punctuated by numerous super interglacials that differ in character and may require more than one systemic explanation of ocean-atmosphere behaviors.