Abstract Quantifying the contribution of poleward oceanic heat transport to the Arctic Ocean is important for making future sea ice and climate predictions. To highlight its potential importance in a warmer world, we present a new record of water-mass exchange between the Atlantic and the Arctic Oceans using the authigenic neodymium isotopic composition of marine sediments from the Fram Strait during the past ∼3.4 to 2.6 Ma. In this study, we target the mid-Pliocene Warm Period (mPWP: 3.264–3.025 Ma) of the Pliocene epoch, the most recent geological analogue for future climate change. We complement our semi-quantitative water mass exchange reconstruction with estimates of spring sea ice concentration based on source-specific biomarkers. Our estimates of volume transport of warm waters into the Arctic Ocean suggest long-term secular changes from the lowest during the Marine Isotope Stage M2 “glacial” (3.312–3.264 Ma), to near complete “Atlantification” of the Eurasian sector of the Arctic Ocean during the mPWP. Orbital forcing is found to be the dominant controlling factor for modulating northward volume transport of Atlantic-derived water masses, with an associated reduction in Arctic spring sea ice concentration of ∼30–35%. Current generation models often produce diverging results, however, and have not yet been validated against proxy data in northern high latitude settings during the mPWP. Our new results of northward volume transport and sea ice extent therefore provide much needed input for validation of current generation models aimed at improving the robustness of future climate modeling in the Arctic.

中文翻译：

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中上新世暖期北极海冰范围减少，同时大西洋气候状况增加

摘要 量化极地海洋热传输对北冰洋的贡献对于未来海冰和气候预测具有重要意义。为了突出其在变暖世界中的潜在重要性，我们利用过去 3.4 至 2.6 Ma 期间弗拉姆海峡海洋沉积物的自生钕同位素组成，展示了大西洋和北冰洋之间水质量交换的新记录。在这项研究中，我们的目标是上新世的中上新世暖期 (mPWP: 3.264–3.025 Ma)，这是未来气候变化的最新地质类似物。我们通过基于源特定生物标志物的春季海冰浓度估计来补充我们的半定量水质量交换重建。我们对暖水进入北冰洋的体积传输的估计表明，从海洋同位素阶段 M2“冰川”（3.312-3.264 Ma）的最低值到北极欧亚部分几乎完全“大西洋化”的长期长期变化mPWP 期间的海洋。发现轨道强迫是调节大西洋来源的水团向北输送的主要控制因素，北极春季海冰浓度降低约 30-35%。然而，当前生成的模型通常会产生不同的结果，并且尚未针对 mPWP 期间北部高纬度地区的代理数据进行验证。