School of Earth and Sustainability, Northern Arizona University, Flagstaff, AZ 86011;
School of Earth and Sustainability, Northern Arizona University, Flagstaff, AZ 86011.
Proc Natl Acad Sci U S A. 2020 Dec 29;117(52):33034-33042. doi: 10.1073/pnas.2016544117. Epub 2020 Dec 7.
Arctic Alaska lies at a climatological crossroads between the Arctic and North Pacific Oceans. The modern hydroclimate of the region is responding to rapidly diminishing sea ice, driven in part by changes in heat flux from the North Pacific. Paleoclimate reconstructions have improved our knowledge of Alaska's hydroclimate, but no studies have examined Holocene sea ice, moisture, and ocean-atmosphere circulation in Arctic Alaska, limiting our understanding of the relationship between these phenomena in the past. Here we present a sedimentary diatom assemblage and diatom isotope dataset from Schrader Pond, located ∼80 km from the Arctic Ocean, which we interpret alongside synthesized regional records of Holocene hydroclimate and sea ice reduction scenarios modeled by the Hadley Centre Coupled Model Version 3 (HadCM3). The paleodata synthesis and model simulations suggest the Early and Middle Holocene in Arctic Alaska were characterized by less sea ice, a greater contribution of isotopically heavy Arctic-derived moisture, and wetter climate. In the Late Holocene, sea ice expanded and regional climate became drier. This climatic transition is coincident with a documented shift in North Pacific circulation involving the Aleutian Low at ∼4 ka, suggesting a Holocene teleconnection between the North Pacific and Arctic. The HadCM3 simulations reveal that reduced sea ice leads to a strengthened Aleutian Low shifted west, potentially increasing transport of warm North Pacific water to the Arctic through the Bering Strait. Our findings demonstrate the interconnectedness of the Arctic and North Pacific on multimillennial timescales, and are consistent with future projections of less sea ice and more precipitation in Arctic Alaska.
阿拉斯加北极地区位于北极和北太平洋之间的气候交叉路口。该地区的现代水文气候正在对迅速减少的海冰做出反应，部分原因是北太平洋热通量的变化。古气候重建提高了我们对阿拉斯加水文气候的认识，但没有研究考察过全新世的北极阿拉斯加海冰、水汽和海洋-大气环流，这限制了我们对过去这些现象之间关系的理解。在这里，我们展示了 Schrader Pond 的沉积硅藻组合和硅藻同位素数据集，该池塘距离北冰洋约 80 公里，我们将其与全新世水文气候和 Hadley 中心耦合模型版本 3 (HadCM3) 模拟的海冰减少情景的综合区域记录进行了解释。古数据分析综合和模型模拟表明，北极阿拉斯加的早全新世和中全新世的特点是海冰较少，来自同位素较重的北极的水汽贡献更大，以及更湿润的气候。在全新世晚期，海冰扩张，区域气候变得更加干燥。这种气候转变与北太平洋环流中阿留申低压的记录变化相吻合，这表明全新世北太平洋和北极之间存在遥相关。HadCM3 模拟表明，海冰减少会导致阿留申低压向西加强，可能会增加通过白令海峡向北极输送温暖的北太平洋水。我们的研究结果表明，在多千年的时间尺度上，北极和北太平洋是相互关联的，这与未来北极阿拉斯加海冰减少和降水增加的预测结果一致。
