Ice Core Reconstruction of North Pacific Climate Variability and Environmental History from the Bona-Churchill Ice Field, Alaska

[摘要]主要研究人员将从位于阿拉斯加东南部Wrangell山脉的博纳山和丘吉尔山之间的峡谷中获取冰芯。冰芯记录将填补该地区高分辨率气候史的重要空白，并将补充和扩展基于树木年轮的气候记录。这些记录将对其他北极冰原的高分辨率冰芯历史套件做出重要贡献，包括格陵兰岛，斯瓦尔巴群岛，加拿大北极高地，风穹冰帽（弗朗茨约瑟夫地，俄罗斯北极）和格陵兰岛。这些极地记录是全球冰芯记录的一部分，包括从西藏、南美洲和非洲的七个低纬度、高海拔地点检索的冰芯记录。这些岩心为确定第四纪气候变化的主要驱动因素和确定冰川时代气候事件的全球同步性的持续努力提供了关键的低纬度代用气候历史。目前，阿拉斯加没有高质量的冰芯记录，所以这些冰芯应该提供重要的新见解。太平洋盆地东北侧高分辨率气候历史资料的缺乏是促进我们了解太平洋地区动态状态的快速和近期变化及其全球联系的主要障碍。特别令人感兴趣的是：1)过去30年的变暖似乎在热带和亚热带以及北美西北部和亚洲北部的高海拔地区被放大；2) 1976- 1977年太平洋盆地气候动态的最新“阶跃”变化；3)最近确定的可能源于热带太平洋的类似enso的多年代际中纬度气候变率的性质。实地项目将包括地球物理和地表研究，旨在选择最佳地点，以恢复两个高分辨率、保存完好的冰芯记录，深度约500米。可溶性和不可溶性气溶胶浓度的实验室测量结果将揭示旱涝期和相对风暴强度。氧同位素分析可以为该地区的温度历史和过去的大气环流模式提供一个代用物。较高的年累积量和较低的年平均温度是物理和化学记录中厚且保存良好的年信号的良好指标，这将允许对过去1000年的年分辨率进行出色的时间控制。完整的记录至少可以追溯到5000年前。最近气候和环境变化的意义必须从全球分散的长期代用气候记录提供的角度来评估。将这些记录从一个极点连接到另一个极点，可以评估这些气候变化的全球性质，并确定高纬度地区与热带地区之间的关键联系，在热带地区，全球热源的变化可以引发气候系统的全球尺度变化。

AbstractOPP- 00-99311ThompsonThe Principal Investigators will retrieve ice cores from the col between Mt. Bona and Mt. Churchill, located in Wrangell Mountains, southeastern Alaska. The ice core records will fill a significant void in the high resolution climate history of this region and will complement and extend the tree ring-based climate records. These records will be an important contribution to the suite of high resolution ice core histories from other north polar ice fields including, Greenland, Svalbard, the High Canadian Arctic the Windy Dome Ice Cap (Franz Josef Land, Russian Arctic) and Greenland. These polar records are part of a global suite of ice core records including those retrieved from seven lower latitude, high altitude sites in Tibet, South America, and Africa. These cores have contributed critical low-latitude proxy climate histories to the continuing efforts to identify the major drivers of Quaternary climate change and to determine the global synchronicity of glacial-age climate events. Currently, there are no high quality ice core records from Alaska, so these cores should provide critical new insights. The paucity of high resolution climate histories from the northeastern side of the Pacific Basin is a major obstacle to advancing our understanding of the rapid and recent changes in the dynamic state of the Pacific region and its global connections. Of particular interest are: 1) the warming of the last 30 years that appears to be amplified at high elevations in the tropics and subtropics and in northwestern North America and northern Asia; 2) the most recent 'step' change in the dynamics of the Pacific Basin climate regime in 1976-77; and 3) the nature of recently identified multi-decadal ENSO-like mid-latitude climate variability that may have its roots in the tropical Pacific.The field program will include geophysical and surface studies designed to select the best site on the col for recovery of two high resolution, well-preserved ice core records to about 500 meters. The results from laboratory measurements of soluble and insoluble aerosol concentrations will reveal drought and wet periods and relative storm intensities. Oxygen isotope analyses should provide a proxy for the temperature history and past atmospheric circulation patterns in this area. The high annual accumulation and cold mean annual temperatures are good indicators for thick and well preserved annual signals in the physical and chemical records that will allow excellent time control with annual resolution for the last 1000 years. The complete record should extend back at least 5,000 years. The significance of recent climatic and environmental variations must be evaluated from a perspective provided by a globally dispersed, long-term proxy climate records. Linking these records from pole to pole allows assessment of the global nature of these climatic variations and identification of critical linkages between the higher latitudes and the tropics where changes in the global heat source can trigger global-scale changes in the climate system.