AI Article Synopsis
- Understanding the Arctic climate's evolution from the warm middle Pliocene to early glacial cycles has been challenging due to a lack of detailed historical data.
- Evidence from Lake El'gygytgyn indicates that summer temperatures were about 8°C warmer than today during 3.6 to 3.4 million years ago, with CO2 levels around 400 ppm.
- The findings reveal intense warmth and rapid cooling events during the transition to the Pleistocene, while Arctic summers remained warmer than present until approximately 2.2 million years ago, which corresponded with the start of significant Northern Hemisphere glaciation.
Article Abstract
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.
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| http://dx.doi.org/10.1126/science.1233137 | DOI Listing |
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