The Pliocene epoch represents an analog for future climate, with atmospheric carbon dioxide concentrations and continental configurations similar to present. Although the presence of multiple positive feedbacks in polar regions leads to amplified climatic changes, conditions in the Pliocene terrestrial Arctic are poorly characterized. High latitude sedimentary records indicate that dramatic glacial advance and decay occurred in the Pliocene Arctic, with attendant effects on global sea-level. Understanding these deposits and their implications for Earth's future requires developing a sense of climatic evolution across the Pliocene–Pleistocene transition and during the intensification of Northern Hemisphere Glaciation (iNHG) ∼2.7 million yr ago (Ma). Here we reconstruct Arctic terrestrial environmental change from 2.82–2.41 Ma (Marine Isotope Stages (MIS) G10–95) using the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) and the isotopic composition of plant leaf waxes (δDwax) in a sedimentary archive from Lake El'gygytgyn, Northeast Russia. Our records reveal changes in proxy behavior across this interval that we attribute to changing boundary conditions, including sea level, sea ice, vegetation and pCO2 during different MISs. We find that brGDGT temperatures and δDwax are decoupled for most of the record, although both show an increasing range of glacial–interglacial variability following iNHG. δDwax is stable from MIS G10–G4 despite changes in vegetation and temperature, suggesting different sources or pathways for moisture to Lake El'gygytgyn during the Late Pliocene.
Bibliographical noteFunding Information:
B.A.K. thanks Helen Habicht and Greg de Wet for useful feedback and discussions. Jeff Salacup is acknowledged for technical laboratory assistance. Norbert Nowaczyk, Volker Wennrich, and Martin Melles provided the age model tie points. We thank two anonymous reviewers and the editor for providing detailed comments that improved the manuscript and figures. This work was supported by National Science Foundation Grant No. 1204087 , a NSF GRF to B.A.K. under Grant No. 1451512 , and a Geological Society of America Graduate Student Research Grant. Drilling operations were funded by the International Continental Scientific Drilling Program , NSF , the German Federal Ministry of Education and Research , the Alfred Wegener Institute and Helmholtz Center Potsdam , the Far East Branch of the Russian Academy of Sciences, the Russian Foundation for Basic Research , and the Austrian Federal Ministry of Science and Research . Sample material used in this project, as well as sampling assistance, was provided by LacCore at the University of Minnesota. Data associated with this study are available on the NOAA National Centers for Environmental Information website.
© 2016 Elsevier B.V.
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- branched GDGT
- n-alkane hydrogen isotopes
- Northern Hemisphere glaciation