Collaborative Research: Holocene Climatic Variability in Southern Alaska -- Quantitative Estimates of Temperature and Precipitation, Warm Intervals, and Possible Cyclicity

该奖项将收集新的数据，以调查阿拉斯加南部全新世气候变异性的性质。该项目产生的新数据将与正在发展的站点网络中的类似记录相结合，以重建北太平洋和整个北极变化的时空格局。研究小组将重建冬季降水(阿拉斯加南部的降水与阿留申低气压的强度呈正相关)和夏季气温(将近期和预计的气候变暖放在长期背景下)。该团队将专注于温暖的间歇期，如早期全新世最高温度、中世纪异常和20世纪。这些间隔的详细气候记录可能提供后工业变暖及其影响的长期背景。来自南阿拉斯加的最近科学结果表明，整个全新世都存在显著的百年尺度周期，与北大西洋地区的报告一致。周期意味着可预测性，因此可能是理解自然变化是否会加剧或缓解人为变暖的关键。南阿拉斯加的海洋气候对大气环流中心的强度和位置的变化高度敏感，特别是阿留申低压，而阿留申低压又受北太平洋(例如太平洋-北美模式)和整个北半球(例如北极涛动)公认的年代际变化模式的调制。此外，这一地区的古气候记录为北至阿拉斯加的古环境研究与南至北太平洋的古海洋学研究提供了重要的联系。一般来说，研究人员将把一个湖泊(有夏季降水记录)与附近一个记录冬季降水的冰川盆地耦合在一起。将对当地天气和湖泊状况进行监测，对湖水进行采样，并对现代/现代沉积物进行分析，以校准用于古气候重建的替代物。夏季温度将利用侏儒组合的传递函数和分析特定有机化合物和硅藻蛋白石的同位素组成的新技术得出。冬季降水量将利用夏季温度与冰川平衡线(ELA)冬季降水量之间的公认相关性来计算。将通过研究冰川前场的地貌和前冰川湖泊中沉积物的物理性质来重建ELA的波动。该奖项特别针对气候变化的相关方面，侧重于气候变暖对适用于政策和生态系统管理决策的时间尺度的影响。本科生和研究生将作为全球变化研究人员跨学科团队的一部分接受第一手培训。研究人员将制作教育材料，通过古环境北极科学(PARCS)网站向公众宣传，并开发公共项目，供美国鱼类和野生动物管理局和美国国家公园管理局用于游客解释活动。

This award will collect new data to investigate the nature of Holocene climatic variability in southern Alaska. New data generated in the project will be integrated with similar records from a developing network of sites to reconstruct the spatial-temporal pattern of change in the North Pacific and across the Arctic. The research team will reconstruct winter precipitation (which in Southern Alaska is positively correlated with the strength of the Aleutian low) and summer temperature (which places recent and projected climatic warming in the long-term context). The team will focus on intervals of warmth such as the early Holocene thermal maximum, the Medieval anomaly, and the 20th century. Detailed climatic records of these intervals may offer the long-term context for post-industrial warming and its impacts.Recent scientific results from Southern Alaska indicate that pronounced centennial-scale cycles occur throughout the Holocene which match those reported from the North Atlantic region. Cycles imply predictability and therefore may be key to understanding whether natural variations may exacerbate or mitigate anthropogenic warming. New data from other sites in Southern Alaska are needed to determine whether these cycles are reproducible and to understand their possible origin in the climatic system.Southern Alaska was chosen for the study because its maritime climate is highly sensitive to changes in the strength and location of atmospheric-circulation centers, especially the Aleutian low, which in turn is modulated by well-recognized inter-decadal modes of variability in the North Pacific (e.g., the Pacific North America pattern) and across the Northern Hemisphere (e.g., the Artic Oscillation). In addition, paleoclimatic records from this region provide an important link between previous paleoenvironmental research in Alaska to the north and paleoceanographic research in the North Pacific to the south.In general, the researchers will couple a lake (with a record of summer precipitation) with a nearby glaciated basin that registers winter precipitation. Monitoring of local weather and limnological conditions, sampling of lake water, and analysis of modern/recent sediment will be conducted to calibrate the proxies used for paleoclimatic reconstructions. Summer temperatures will be derived using transfer functions of midge assemblages and new techniques for analyzing the isotopic composition of specific organic compounds and diatom opal. Winter precipitation will be derived using a well-established correlation between summer temperature and winter precipitation at the equilibrium line of glaciers (ELA). Fluctuations in ELA will be reconstructed by studying the geomorphology of glacier forefields and the physical properties of sediment in proglacial lakes. This award targets particularly relevant aspects of climatic change by focusing on the impacts of warmth on time scales applicable to policy and ecosystem management decisions. Undergraduate and graduate students will receive first-hand training as part of an interdisciplinary team of global-change researchers. The researchers will produce educational materials for outreach to the general public via the Paleoenvironmental Arctic Sciences (PARCS) website and by development of public programs that will be used for visitor interpretive activities by the US Fish and Wildlife Service and the US National Park Service.