Collaborative Research: Holocene glacier length variations along the spine of the American Cordilleras and their climatic significance

在过去的世纪里，全球冰川的退缩是全球变暖最明显的信号之一，但它提出了两个仍然模糊的基本问题：目前的冰川范围有多反常，以及工业时代之前的长期冰川趋势是什么？该项目将重建在全新世（过去11，000年）期间，从北极到巴塔哥尼亚的美洲长度的十几个冰川比今天更大或更小的频率。我们采取以社区为基础的方法来降低成本，积极的冰川科学家在他们自己的实地活动中免费收集样本，为这个项目做出贡献。我们的研究结果将提供一个地质透镜，通过它来观察现代气候变化，并为用于模拟冰川对未来变暖的反应的计算机模型提供古测试-这对某些地区的淡水资源和全球海平面上升至关重要。我们将重建冰川的历史，应用原位14 C-10 Be计时器在每个冰川终点的几个样品的冰前基岩。这种技术能够确定全新世冰川前进超过和后退到其当前终点的哪一部分，通过量化暴露期间14 C和10 Be的积累，以及由于其半衰期短得多的14 C在冰盖期间的优先损失。我们的纬度样带旨在最大限度地了解冰川如何对轨道变化作出反应，以及低纬度和高纬度之间以及整个半球之间的气候如何耦合。考虑到全新世冰川趋势可能随纬度变化很大，我们的大规模重建也将提供评估当前全球冰川退缩所需的背景。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

The worldwide retreat of glaciers over the past century is one of the clearest signals of global warming, but it raises two basic questions that remain hazy: how anomalous are current glacier extents, and what were long-term glacier trends prior to the industrial era? This project will reconstruct how often during the Holocene (the last 11,000 years) a dozen glaciers down the length of the Americas, from the Arctic to Patagonia, were larger versus smaller than today. We take a community-based approach to reduce cost, with active glacier scientists collecting samples gratis during their own field campaigns to contribute to this project. Our results will provide a geologic lens through which to view modern climate change, and offer a paleo-test for computer models used to simulate glacier responses to future warming -- important to freshwater resources in some areas and global sea level rise. We will reconstruct glacier histories by applying the in situ 14C-10Be chronometer to several samples of proglacial bedrock at each glacier terminus. This technique is able to determine what portion of the Holocene a glacier advanced beyond and retreated behind its current terminus by quantifying the buildup of both 14C and 10Be during periods of exposure and the preferential loss of 14C during episodes of ice cover due to its much shorter half-life. Our latitudinal transect is designed to maximize understanding of how glaciers responded to orbital variations, as well as how climate may have been coupled between the low and high latitudes and across the hemispheres. Given that Holocene glacier trends may have varied substantially with latitude, the broad scale of our reconstructions will also provide the context needed for evaluating current glacier retreat around the world.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.