Biomarker analyses on sediment core BP00-07/07 from the southern Kara Sea (Arctic Ocean)

The Holocene is characterized by the late Holocene cooling trend as well as by internal short-term centennial fluctuations. As Arctic sea ice acts as a significant component (amplifier) within the climate system, investigating its past long- and short-term variability and controlling processes is beneficial for climate future predictions. This study presents the first biomarker-based (IP25 and PIP25) sea ice reconstruction from the Kara Sea (Core BP00-07/07), covering the last 8 ka. These biomarker proxies reflect conspicuous short-term sea ice variability during the last 6.5 ka that is identified unprecedentedly in the source region of Arctic sea ice by means of a direct sea ice indicator. Prominent peaks of extended sea ice cover occurred at ~3, ~2, ~1.3 and ~0.3 ka Spectral analysis of the IP25 record revealed ~400- and ~950-year cycles. These periodicities may be related to the Arctic/North Atlantic Oscillation (AO/NAO), but probably also to internal climate system fluctuations. This demonstrates that sea ice belongs to a complex system that more likely depends on multiple internal forcing.

全新世（Holocene）以晚期降温趋势及内部短期百年尺度波动为典型特征。北极海冰作为气候系统中发挥关键调控作用的放大器组分，对其过去长、短期变化与控制机制开展研究，对未来气候预测具有重要参考价值。本研究首次基于生物标志物IP25与PIP25，对喀拉海BP00-07/07岩芯开展了覆盖过去8千年的海冰重建工作。上述生物标志物代用指标清晰反映了过去6.5千年间显著的短期海冰变化——这是在北极海冰源区中，首次通过直接海冰代用指标识别出的此类信号。海冰覆盖范围扩张的显著峰值出现在约3 ka、2 ka、1.3 ka及0.3 ka时段。对IP25记录的频谱分析显示，其存在约400年与950年的周期性信号。这些周期特征可能与北极/北大西洋涛动（AO/NAO）相关，同时也可能对应气候系统内部的自然波动。这表明海冰属于复杂气候系统的组成部分，其变化更可能受多重内部强迫共同调控。