RT Journal Article
SR Electronic
T1 Pliocene Warmth, Polar Amplification, and Stepped Pleistocene Cooling Recorded in NE Arctic Russia
JF Science
JO Science
FD American Association for the Advancement of Science
SP 1421
OP 1427
DO 10.1126/science.1233137
VO 340
IS 6139
A1 Brigham-Grette, Julie
A1 Melles, Martin
A1 Minyuk, Pavel
A1 Andreev, Andrei
A1 Tarasov, Pavel
A1 DeConto, Robert
A1 Koenig, Sebastian
A1 Nowaczyk, Norbert
A1 Wennrich, Volker
A1 Rosén, Peter
A1 Haltia, Eeva
A1 Cook, Tim
A1 Gebhardt, Catalina
A1 Meyer-Jacob, Carsten
A1 Snyder, Jeff
A1 Herzschuh, Ulrike
YR 2013
UL http://science.sciencemag.org/content/340/6139/1421.abstract
AB Climate and the atmospheric concentration of CO2 are closely linked. Brigham-Grette et al. (p. 1421, published online 9 May) present data from Lake El'gygytgyn, in northeast Arctic Russia, that shows how climate varied between 3.6 and 2.2 million years ago, an important interval in the global cooling trend that accelerated rapidly at the end of the Miocene. Summer temperatures were about 10°C warmer than today, even though the concentration of atmospheric CO2 was similar. Understanding the evolution of Arctic polar climate from the protracted warmth of the middle Pliocene into the earliest glacial cycles in the Northern Hemisphere has been hindered by the lack of continuous, highly resolved Arctic time series. Evidence from Lake El’gygytgyn, in northeast (NE) Arctic Russia, shows that 3.6 to 3.4 million years ago, summer temperatures were ~8°C warmer than today, when the partial pressure of CO2 was ~400 parts per million. Multiproxy evidence suggests extreme warmth and polar amplification during the middle Pliocene, sudden stepped cooling events during the Pliocene-Pleistocene transition, and warmer than present Arctic summers until ~2.2 million years ago, after the onset of Northern Hemispheric glaciation. Our data are consistent with sea-level records and other proxies indicating that Arctic cooling was insufficient to support large-scale ice sheets until the early Pleistocene.