A 3.6 Ma sedimentological, geochemical and palynological record of sediment core ICDP5011-1 in Lake Elgygytgyn, NE Russia@en

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, NE Arctic Russia, shows that 3.6-3.4 million years ago, summer temperatures were ~8°C warmer than today when pCO2 was ~400 ppm. 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 Ma, 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.长期以来，由于缺乏连续且高分辨率的北极时间序列数据，解析北极极地气候从中上新世持续暖期向北半球最早冰期旋回的演化历程始终存在瓶颈。来自俄罗斯东北北极区域的埃尔吉特金湖（Lake El'gygytgyn）的代用证据显示，在距今360万至340万年前，当大气CO₂分压（pCO₂）约为400 ppm时，当地夏季气温较现今偏高约8℃。多代用指标（multiproxy）证据表明，上新世中期存在极端暖化与极地放大效应，在上新世-更新世过渡期出现阶段性骤冷事件，且直至约220万年前（北半球冰川作用启动之后），北极夏季气温仍高于现今水平。本研究数据与海平面记录及其他代用指标结果一致，表明北极降温幅度不足以支撑大规模冰盖发育，直至早更新世时期。