Collaborative Research: Paleohistory of the Larsen Ice Shelf: Phase II

拉森冰架是南极洲第三大冰架，自20世纪90年代中期以来，它一直处于灾难性的衰退状态。拟议中的拉森冰架海洋地质工作建立在我们之前的NSF-OPP资助的基础上，并打算测试一个工作假设，即拉森B冰架系统自10000年前海平面上升期间形成以来一直是南极洲冰川系统的一个稳定组成部分。这一结论，如果得到我们所提出的工作的观测结果的支持，将是确定目前在整个半岛发生的快速区域变暖的独特性和后果的重要的第一步。我们以前在拉森A和B河口的工作使我们能够认识到过去冰架波动的特征及其对海洋和生物环境的影响。我们还克服了南极海洋序列中标准放射性碳测年的许多局限性，方法是利用地球磁场强度的变化来对比沉积物记录，并利用特定的有机化合物（而不是大量沉积物）来进行放射性碳测年。我们打算追求这些分析上的进步，并将我们的沉积物岩心地层学扩展到拉森B冰架最近崩塌所暴露的地区以及拉森C冰架附近的地区。除了核心回收计划，我们打算利用我们独特的进入冰架前沿的途径，继续我们对冰雪地层学、海洋学特征和海底特征的观察。沉积物捕集器也将被部署，以便测量冰川碎片的输入，这些碎片现在因冰架崩塌而激增。该提案是一个多机构、国际（美国、意大利和加拿大）的努力，结合了各种学科的现有专业知识，并将研究计划整合到主要本科院校的教育工作中，但也包括一些研究生教育。这是一个为期三年的项目，为了适应RVIB L.M. Gould的时间表，该项目有灵活的实地季节计划。南极半岛正在经历比地球上几乎任何地方都要严重的变暖，这可能与人类引起的温室效应有关。我们提出的工作有助于了解这些变化在哪里首先发生，对环境的影响最大。

The Larsen Ice Shelf is the third largest ice shelf in Antarctica and has continued a pattern of catastrophic decay since the mid 1990's. The proposed marine geologic work at the Larsen Ice Shelf builds upon our previous NSF-OPP funding and intends to test the working hypothesis that the Larsen B Ice Shelf system has been a stable component of Antarctica's glacial system since it formed during rising sea levels 10,000 years BP. This conclusion, if supported by observations from our proposed work, is an important first step in establishing the uniqueness and consequences of rapid regional warming currently taking place across the Peninsula. Our previous work in the Larsen A and B embayments has allowed us to recognize the signature of past ice shelf fluctuations and their impact on the oceanographic and biologic environments. We have also overcome many of the limitations of standard radiocarbon dating in Antarctic marine sequences by using variations in the strength of the earth's magnetic field for correlation of sediment records and by using specific organic compounds (instead of bulk sediment) for radiocarbon dating. We intend to pursue these analytical advances and extend our sediment core stratigraphy to areas uncovered by the most recent collapse of the Larsen B Ice Shelf and areas immediately adjacent to the Larsen C Ice Shelf. In addition to the core recovery program, we intend to utilize our unique access to the ice shelf front to continue our observations of the snow/ice stratigraphy, oceanographic character, and ocean floor character. Sediment traps will also be deployed in order to measure the input of debris from glaciers that are now surging in response to the ice shelf collapse. This proposal is a multi-institutional, international (USAP, Italy, and Canada) effort that combines the established expertise in a variety of disciplines and integrates the research plan into the educational efforts of primarily undergraduate institutions but including some graduate education. This is a three-year project with field seasons planned with flexibility in order to accommodate schedules for the RVIB L.M. Gould. The Antarctic Peninsula is undergoing greater warming than almost anywhere on Earth, perhaps associated with human-induced greenhouse effects. Our proposed work contributes to understanding of these changes where they are occurring first and with greatest magnitude and impact upon the environment.