Doctoral Dissertation Research: Analyzing Tropical Alpine Glacier Dynamics During Middle-Holocene Warming

博士论文研究：分析中全新世变暖期间的热带高山冰川动力学

• 批准号: 1558358
• 负责人: Meredith Kelly
• 金额: $ 1.56万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-01 至 2018-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1558358&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Analyzing; Tropical

This doctoral dissertation research project will develop records of past glacier extents in one set of mountains in a tropical setting and will assess the sensitivity of glaciers in this and similar regions to changes in climatic conditions, such as alternate temperature and precipitation regimes. The project will provide new information and insights to address the degree to which alpine tropical glaciers are especially sensitive to changing climatic and other environmental conditions. The study region is one for which previous evidence seemed to indicate that alpine glaciers persisted during the middle of the Holocene Epoch, a period when evidence indicates that temperatures were as warm as or warmer than the present time period. The project helps to assess the sensitivity of these glaciers to warming temperatures in order to better ascertain both the timing and magnitude of past glacier fluctuations. By reconstructing past glacier extents in tropical regions like this, this project will improve basic understanding about the factors and dynamics that affect tropical glaciers as well as their sensitivity to a changing environment. The project also will provide information that will yield more accurate predictions of future glacier mass loss, project findings will facilitate planning and development activities in tropical regions, where glaciers provide crucial freshwater resources and ongoing glacier recession will impact directly the livelihoods and wellbeing of communities. The project will provide additional education and training benefits by engaging undergraduate students in some facets of the project and through presentations based on the project in elementary and secondary school classrooms in Vermont and New Hampshire. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.The ongoing retreat of tropical glaciers has been highlighted as one manifestation of contemporary change in environmental conditions around the Earth, but the sensitivity of these glaciers to projected future climate conditions is uncertain. Through this dissertation research project, the doctoral student will improve the understanding of tropical glacier response to warmer temperatures by determining the extents of glaciers in tropical eastern Africa over a period roughly 8,000 to 4,000 years ago, when the region was as warm as or warmer than at present. The student will use detailed geomorphic mapping and surface exposure dating of glacial deposits in the Rwenzori Mountains to determine glacier extents during the current interglacial period known as the Holocene Epoch, which extends from about 11,600 years ago to the present. She will employ a surface-exposure dating method that relies on measurements of the cosmogenic nuclide beryllium-10, which is produced in rock surfaces over time due to the influx of cosmic rays. The project will be the first study to develop a beryllium-10-based chronology of Holocene glacier extents in tropical eastern Africa. The student will compare the Rwenzori glacier chronology with records of temperature, precipitation, and glacier extents from other locations in tropical East Africa in order to assess the regional climate conditions and patterns of glacier fluctuations. These results will be compared with Holocene glacier extents in tropical South America. Determining whether glaciers across the global tropics fluctuated synchronously or asynchronously during the Holocene Epoch will provides information for evaluating the dynamics associated with changing global climatic conditions. Project results will advance efforts to model glaciers within future warming scenarios, thereby providing a means to test hypotheses about the possible mechanisms that transmitted climate signals across the globe during the Holocene Epoch.

该博士论文研究项目将记录热带环境中一组山脉过去冰川范围的记录，并将评估该地区和类似地区的冰川对气候条件变化（例如交替温度和降水状况）的敏感性。 该项目将提供新的信息和见解，以解决高山热带冰川对气候和其他环境条件变化特别敏感的程度。 该研究地区之前的证据似乎表明高山冰川在全新世中期持续存在，有证据表明这一时期的气温与当前时期一样温暖或更高。 该项目有助于评估这些冰川对气温变暖的敏感性，以便更好地确定过去冰川波动的时间和幅度。 通过重建像这样的热带地区过去的冰川范围，该项目将提高对影响热带冰川的因素和动态及其对环境变化的敏感性的基本了解。 该项目还将提供信息，对未来冰川质量损失进行更准确的预测，项目结果将促进热带地区的规划和开发活动，在热带地区，冰川提供重要的淡水资源，持续的冰川衰退将直接影响社区的生计和福祉。 该项目将通过让本科生参与该项目的某些方面以及在佛蒙特州和新罕布什尔州的中小学课堂上进行基于该项目的演示来提供额外的教育和培训效益。 作为博士论文研究改进奖，该奖项还将为有前途的学生建立强大的独立研究生涯提供支持。热带冰川的持续退缩已被视为当代地球环境条件变化的一种表现，但这些冰川对预计未来气候条件的敏感性尚不确定。 通过这个论文研究项目，博士生将确定大约 8,000 至 4,000 年前热带东部非洲冰川的范围，当时该地区的气温与现在。 学生将使用鲁文佐里山脉冰川沉积物的详细地貌测绘和表面暴露测年来确定当前称为全新世的间冰期（从大约 11,600 年前一直延续到现在）的冰川范围。 她将采用一种表面暴露测年方法，该方法依赖于宇宙成因核素铍10的测量，铍10是由于宇宙射线的流入而随着时间的推移在岩石表面产生的。 该项目将是第一个针对东非热带地区全新世冰川范围建立基于铍 10 年代学的研究。 学生将把鲁文佐里冰川年代学与热带东非其他地点的温度、降水和冰川范围记录进行比较，以评估区域气候条件和冰川波动模式。 这些结果将与热带南美洲的全新世冰川范围进行比较。 确定全新世期间全球热带地区的冰川是否同步或异步波动将为评估与全球气候条件变化相关的动态提供信息。 项目结果将推动在未来变暖情景中模拟冰川的努力，从而提供一种方法来检验关于全新世期间在全球范围内传输气候信号的可能机制的假设。