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

合作研究：阿拉斯加南部全新世气候变化——温度和降水、温暖间隔和可能的周期性的定量估计

• 批准号: 0318404
• 负责人: Feng Sheng Hu
• 金额: $ 39.01万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-15 至 2008-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0318404&HistoricalAwards=false
• 关键词: Collaborative; Research; Holocene; Climatic; Variability

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.

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化的性质。该项目产生的新数据将与来自一个不断发展的地点网络的类似记录相结合，以重建北太平洋和整个北极的时空变化模式。该研究小组将重建冬季降水（在阿拉斯加南部与阿留申低压的强度呈正相关）和夏季温度（将最近和预测的气候变暖置于长期背景下）。该小组将重点关注温暖的间隔，如早期全新世热最大，中世纪的异常，和20世纪。这些间隔的详细气候记录可能提供长期的背景下，后工业变暖及其影响。最近的科学研究结果表明，从南阿拉斯加州的明显百年尺度的周期发生在整个全新世与北大西洋地区的报告相匹配。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减缓人为变暖的关键。需要从阿拉斯加南部其他地点获得新的数据来确定这些循环是否是可重复的，并了解它们在气候系统中的可能起源。阿拉斯加南部被选为研究地区是因为其海洋性气候对大气环流中心的强度和位置的变化非常敏感，特别是阿留申低压，而这又受到北太平洋公认的年代际变率模式的调制（例如，太平洋北美模式）和横跨北方半球（例如，（Artic Oscillation）此外，该地区的古气候记录为北部阿拉斯加的古环境研究和南部北太平洋的古海洋学研究提供了重要的联系。一般来说，研究人员将一个湖泊（有夏季降水记录）与附近记录冬季降水的冰川盆地结合起来。将对当地天气和湖沼条件进行监测，对湖水进行取样，并对现代/近期沉积物进行分析，以校准用于古气候重建的代用指标。夏季温度将使用传递函数的吸浆虫组合和新技术分析特定的有机化合物和硅藻蛋白石的同位素组成。冬季降水量将利用冰川平衡线（ELA）处夏季温度和冬季降水量之间的既定相关性得出。将通过研究冰川前缘的地貌和冰前湖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，重点关注温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）网站向公众推广，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。