Coralline algae as novel archive to decipher past North Atlantic/Arctic sea-ice cover and water temperature dynamics: climate trends and decadal variability

近几十年来，北大西洋北部的气候和海洋变率经历了迅速变化的条件，包括北极海冰覆盖面积加速下降、大量海洋变新鲜趋势以及与海洋变暖有关的格陵兰岛主要冰盖边缘的剧烈变化。最显著的地表变暖发生在加拿大东北部的北极和格陵兰岛。这些趋势已经开始改变生态系统和人类行为，甚至可能影响北极以外的大规模大气环流。然而，气候模型不仅无法预测观测到的北极海冰减少的速度和程度，而且还严重低估了最近的地表变暖。主要原因是缺乏数据。因此，探索高分辨率的温带海洋档案将为重建长期气候趋势和变率提供一个视角，从而改善气候模式。该提案将把重点放在附着在海底的海洋植物珊瑚藻上，作为新的气候记录仪。珊瑚藻具有长达数世纪的寿命，并显示出清晰的年生长带，允许分年分解重建古气候。这个项目与之前的所有方法不同：1。这将是第一次从关键地点，如加拿大北极、格陵兰岛和斯匹次卑尔根岛，建立一个多世纪的次年解析古记录网络。研究人员探索了长寿命的珊瑚藻，以重建过去几十年到几个世纪，甚至可能是一千年的海水温度、海冰和冰盖的季节性持续时间以及淡水通量的动态。3. 地球化学和生长代用物的结合是重建过去变率、探测大尺度气候模式和量化人为变暖影响的有力工具。4. 将对区域变率模式进行研究，并与其他气候档案进行比较。5. 最后，藻类多代理重建将与千年尺度的古模拟相结合，以更好地了解大气-海洋相互作用。由于亚北极和北极环境的仪器数据很少，这些新记录将直接有助于提高对工业革命前后气候动力学的理解。

In recent decades northern North Atlantic climate and ocean variability have experienced rapidly changing conditions, including accelerated decline in arctic sea-ice cover, substantial oceanic freshening trends, and drastic changes on the margins of Greenland's major ice sheets linked to ocean warming. Most prominent surface warming occurred in the northeastern Canadian Arctic and Greenland. These trends have already started altering ecosystems as well as human behaviour and may even influence the large-scale atmospheric circulation beyond the Arctic. However, climate models have not only failed to predict speed and extent of the observed Arctic sea-ice decline, but they also significantly underestimate recent surface warming. The major reason is lack of data. Hence the exploration of high-resolution marine archives from the extratropics will provide a perspective to reconstruct long-term climatic trends and variability, and in turn will improve climate models. The proposal will focus on encrusting coralline algae, marine plants growing attached to the seafloor, as novel climate recorders. Coralline algae have a multi-century lifespan and display clear annual growth bands, permitting sub-annually resolved reconstructions of paleoclimate. This project differs from all previous approaches in that: 1. For the first time a multicentury network of subannually-resolved paleo-records will be built from key sites, such as the Canadian Arctic, Greenland, and Spitsbergen. 2. Long-lived coralline algae are explored to reconstruct the past dynamics of seawater temperature, seasonal duration of sea-ice and ice cover, as well as freshwater flux over the past decades to centuries, and potentially even millennium. 3. The combination of geochemical and growth proxies are the powerful tools to reconstruct past variability, detect large-scale climate patterns and quantify the impact of anthropogenic warming. 4. Regional patterns of variability will be studied and compared to other climate archives. 5. Finally, algal multiproxy reconstructions will be integrated with millennium-scale paleo-simulations to better understand atmosphere-ocean interactions. Since instrument-derived data in subarctic and arctic environments are scarce, these new records will directly contribute to an improved understanding of climate dynamics prior to and since the industrial revolution.