Reliable high‐resolution, pre‐observational‐period sea‐ice datasets are rare but critical for contextualizing recent sea‐ice declines and future scenarios. We combine sedimentary ancient DNA of the sea‐ice dinoflagellate Polarella glacialis (Pgla‐sedaDNA) with selected highly branched isoprenoid (HBI) biomarkers alongside other indicators to reconstruct sub‐decadal sea‐ice changes in a marine archive from the Antarctic Peninsula that extends to ~ 1900 CE. Pre‐1940 CE, the continuously present sea‐ice biomarker IPSO25 yet absent Pgla‐sedaDNA, along with low open‐water biomarkers and total organic carbon (TOC), imply more prominent seasonal sea ice and lower productivity under cooler climate. Post‐1940 CE, rising Pgla‐sedaDNA and open‐water HBIs under climate warming reflect young ice with a retreating sea‐ice edge. Over the last two decades, lower Pgla‐sedaDNA, higher open‐water HBIs and TOC infer known warming, sea‐ice reduction, and increased productivity. Our multiproxy‐based palaeo‐histories agree well with observational data, highlighting the potential of this combination of proxies for nuanced and long‐term sea‐ice reconstructions.

中文翻译：

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沉积古 DNA 和 HBI 生物标志物作为海冰指标：南极峡湾环境的补充方法


可靠的高分辨率、观测前海冰数据集很少见，但对于了解最近海冰减少和未来情景至关重要。我们将海冰甲藻 Polarella glacialis (Pgla-sedaDNA) 的沉积古 DNA 与选定的高度分支的类异戊二烯 (HBI) 生物标志物以及其他指标相结合，以重建从南极半岛延伸到的海洋档案中的亚十年海冰变化。 ~ 公元 1900 年。 1940 年之前，持续存在的海冰生物标志物 IPSO25 但缺乏 Pgla-sedaDNA，以及较低的开放水域生物标志物和总有机碳 (TOC)，意味着在较冷的气候下，季节性海冰更加突出，生产力较低。公元 1940 年之后，气候变暖下 Pgla-sedaDNA 和开放水域 HBI 的上升反映了年轻的冰和海冰边缘的后退。在过去的二十年中，较低的 Pgla-sedaDNA、较高的开放水域 HBI 和 TOC 推断出已知的变暖、海冰减少和生产力增加。我们基于多代理的古历史与观测数据非常吻合，突显了这种代理组合在细致和长期海冰重建方面的潜力。