Collaborative Research: P2C2--Evaluating Controls on Holocene Glacier Fluctuations and Climate Variability in the Southern Peruvian Andes

项目的技术说明该项目的主要目标是在秘鲁南部的Cordillera VilCabamba建立准确和精确的冰川年龄，并量化全新世冰川对气候变化的敏感性，最终目标是阐明热带地区全新世的气候变异性和控制。维尔卡班巴的初步工作发现，在全新世早期和小冰期期间，冰川取得了显著进展，揭示了一系列与欧洲冰川记录广泛相关的事件。这些试验结果表明了热带和北大西洋地区之间的气候遥相关，但需要更广泛的数据来自信地确定区域冰川模式和全新世气候控制。该项目将在很大程度上建立在初步发现的基础上，利用最近的方法学进步，利用最新的方法进步，确定极年轻(200年)和精确的同位素年龄，通过重建维尔卡班巴其他山谷的冰川历史，使用宇宙产生的10Be冰川表面暴露年代。补充的~(14)C年龄和古气候替代数据将从位于10Be年代的冰河流域之间的沼泽中恢复的沉积岩芯中获得。这些冰雹的独立14C年龄控制提供了开发10Be产生率的新的局部校准的潜力。古冰川质量平衡对特定气候变量规定变化的敏感性将通过使用冰川表面能量-质量平衡模型进行模拟来量化，从而能够估计主要作用力，如温度、降水和太阳辐射对冰川范围的相对作用。将评估假定的气候变化机制与综合年龄控制和模拟结果的一致性程度，从而能够确定热带安第斯地区全新世冰川和气候变化的可能驱动因素。更广泛的意义和重要性热带地区在触发、放大和传递全球气候信号方面的作用仍然是气候科学中激烈辩论的主题。气候敏感的热带山地冰川过去波动的准确日期记录是反映过去气候变化及其原因的区域趋势的最佳指标之一。秘鲁拥有世界上71%的冰川--S，现在的热带冰川，并包含了大量以前冰川扩张的地质证据。然而，该地区过去冰川波动的年表很少，特别是在全新世(过去约11,700年)期间。该项目的新结果将大大有助于理解秘鲁全新世冰川事件的时间和气候对冰川作用的主要影响。重要的是，新的冰川年表将增加从附近冰芯、湖泊和海洋地点形成的过去气候的记录，以及其他新兴的冰川历史，有助于更全面地描述区域气候变化及其环境后果。因此，结果将使我们能够严格审查全新世期间热带气候变化的根本原因，包括与理解现代和未来气候变化有关的最近气候变化。更好地了解过去的安第斯冰川对于预测未来气候变化的冰川反应和对当地水资源的影响，以及确定对该区域包括印加和前印加社会在内的古代文明的环境影响至关重要。这项研究将为新汉普郡大学和哥伦比亚大学的本科生和研究生提供现场技术、实验室方法和数值建模方面的培训。该项目还将扩大美国早期职业科学家与加拿大和秘鲁合作者之间的富有成效的合作。这一跨国项目团队的组建将加强每个参与机构的研究计划、设施和外展活动的发展。研究活动还将通过改进旨在提高广泛使用的同位素测年方法的精度的实验室方法，促进技术开发。

Technical description of the projectThe main objectives of this project are to develop accurate and precise moraine ages in the Cordillera Vilcabamba of southern Peru, and to quantify the sensitivity of Holocene glaciers to climate changes, with the ultimate goal of elucidating Holocene climate variability and controls in the tropics. Initial work in the Vilcabamba has identified prominent glacial advances during the early Holocene and the 'Little Ice Age' interval, revealing a sequence of events that is broadly correlative with glacial records in Europe. These pilot results suggest climate teleconnections between the tropics and the North Atlantic region, but a more extensive array of data is needed to confidently identify regional glacial patterns and Holocene climate controls. This project will build substantially on initial findings by reconstructing glacial histories in additional valleys in the Vilcabamba using cosmogenic 10Be surface exposure dating of moraines, taking advantage of recent methodological advances that allow determination of extremely young (200 year) and precise isotopic ages. Supplementing 14C ages and paleoclimate proxy data will be obtained from sediment cores recovered from bogs situated between 10Be-dated moraines. Independent 14C age control for these moraines offers the potential to develop a new local calibration of the 10Be production rate. The sensitivity of paleo-glacier mass balances to prescribed changes in specific climatic variables will be quantified by performing simulations with a glacier surface energy-mass balance model, thus allowing an estimation of the relative roles of major forcings such as temperature, precipitation, and solar radiation on glacier extent. Posited mechanisms of climate change will be assessed for their degree of consistency with the integrated age control and modeling results, enabling identification of likely drivers of Holocene glaciations and climate variability in the tropical Andes.Broader significance and importanceThe role of the tropics in triggering, amplifying, and transmitting global climate signals remains a topic of vigorous debate in climate science. Accurately dated records of past fluctuations in climatically sensitive tropical mountain glaciers are among the best indicators of regional trends in past climate changes and their causes. Peru harbors 71% of the world?s present-day tropical glaciers, and contains abundant geologic evidence of former glacier expansions. However, chronologies of past glacier fluctuations in this region are scarce, particularly during the Holocene epoch (the past ~11,700 years). New results from this project will contribute significantly toward an understanding of both the timing of Holocene glacier events in Peru and the predominant climatic influences on glaciation. Importantly, the new glacier chronologies will augment records of past climates developed from nearby ice core, lake, and marine sites as well as other emerging glacial histories, contributing to a more comprehensive characterization of regional climate changes and their environmental consequences. Results will thus allow for a rigorous examination of the underlying causes of tropical climate variability during the Holocene, including recent climate shifts relevant to understanding modern and future climate change.An improved understanding of past Andean glaciations is crucial for predicting glacier responses to future climate change and consequences for local water resources, and for identifying environmental impacts on ancient civilizations in the region, including Inca and pre-Inca societies. This study will provide training in field techniques, laboratory methods, and numerical modeling for undergraduate and graduate students at the University of New Hampshire and Columbia University. The project will also expand on a productive collaboration between early career U.S. scientists and collaborators in Canada and Peru. Assembly of this multinational project team will enhance the development of research programs, facilities, and outreach activities at each participating institution. Research activities will also contribute to technique development by refining laboratory methods aimed at increasing the precision of widely used isotopic dating methods.