Integrating novel molecular techniques to disentangle the roles of climate, time, and human agency on the evolution of the Icelandic landscape

整合新颖的分子技术来阐明气候、时间和人类因素对冰岛地貌演变的作用

• 批准号: 1836981
• 负责人: Gifford Miller
• 金额: $ 93.5万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1836981&HistoricalAwards=false
• 关键词: Integrating; novel; molecular; techniques; disentangle

Project AbstractNon-Technical Description:Significant uncertainties remain in our ability to predict how ecosystems will respond and landscapes will change as the Arctic continues to warm faster than the global average. We can look to past warm times in recent Earth history to better constrain how the Earth system will respond to warming over the coming century. At the end of the last ice age Earth's orbit was such that the Northern Hemisphere received nearly 10% more solar energy in summer than at present. That extra energy was sufficient to melt almost all Iceland's glaciers, and the Sagas say birch forests extended from the shores to the mountains. Molecular compounds that track changes in temperature, aridity, and vegetation history are contained within the sediment deposited in Icelandic lakes and nearby composite soils over the past 12,000 years. These "proxies" provide a means to accurately reconstruct a continuous history of climate and ecosystem status across Iceland since the end of the last ice age. This research benefits from recent advances in the recovery of DNA from sedimentary archives and in organic geochemistry to isolate biomarkers that track temperature and moisture balance. A pervasive feature of the contemporary Icelandic landscape is widespread soil erosion, but whether that erosion is a result of human settlement and pastoral activity or climate change remains debated. Geochemical proxies related to soil erosion preserved in well-dated lake sediment are targeted to disentangle the roles of climate and humans in Iceland's soil erosion history. This project helps launch an early-career Latino scientist, provides international exposure to a recent PhD as postdoc in a DNA laboratory in Norway, and supports a new PhD student, as well as supporting and mentoring motivated undergraduate students, who gain research experience in a highly relevant field. With an embedded journalist communicating the potential effects of climate change derived from this research to the wider public is enhanced. Technical Description:The Arctic is currently warming twice as fast as the global average with summer temperatures predicted to be 4 to 6 degrees C above late 20th Century averages by the year 2100. Amplified warming in the Arctic is expected to result in a northward shift in woody plants. The increase in woody vegetation will reduce surface albedo and increase atmospheric water vapor, positive feedback mechanisms that are currently poorly constrained in climate models. In Iceland, stratified, securely-dated, lake sediment records span the current interglacial (Holocene) and contain a rich archive of sedimentary ancient DNA (sedaDNA) and lipid biomarker proxies for temperature (brGDGTs), hydrology (delta2-Hwax) and human agency (fecal sterols and PAHs). The analysis of modern soil and lake surface sediment networks will provide calibrations that enhance the community's understanding of these promising new molecular proxies and facilitate the development of regional training sets. Merging the local calibrations with similar measurements downcore in lake sediment and stratified aeolianites will enable reliable reconstructions of past ecosystems and their dependence on summer temperature and hydroclimate. The novel integration of these datasets will provide transformative new insights into 1) how much warmer was the early Holocene in Iceland relative to today, 2) when and to what elevation woody plants established themselves during early Holocene warmth, and 3) to what extent climate, volcanism and/or Norse settlement led to the widespread soil erosion apparent across the Icelandic landscape today. Anticipated results from this project provide key datasets needed to inform policy and improve forecasts of a rapidly warming Arctic.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.

项目Abstractnon-technical描述：我们预测生态系统将如何响应的能力仍然存在重大不确定性，并且随着北极持续的速度比全球平均水平更快，风景会发生变化。 我们可以在最近的地球历史上度过过去的温暖时期，以更好地限制地球体系在未来世纪将如何响应变暖。在最后一个冰河时代的轨道结束时，地球的轨道使北半球在夏季收到的太阳能比目前高出近10％。这种额外的能量足以融化几乎所有冰岛的冰川，萨加斯说，桦木森林从海岸延伸到山脉。在过去的12，000年中沉积在冰岛湖泊和附近的复合土壤中的沉积物中，有跟踪温度，干旱和植被病史变化的分子化合物。这些“代理人”提供了一种手段，可以准确地重建自上届冰河时代结束以来冰岛的气候和生态系统地位的连续历史。这项研究受益于从沉积档案中恢复DNA和有机地球化学的最新进展，从而隔离了跟踪温度和水分平衡的生物标志物。当代冰岛景观的一个普遍特征是广泛的土壤侵蚀，但是这种侵蚀是人类定居和田园活动还是气候变化的结果。与保存在良好的湖泊沉积物中的土壤侵蚀相关的地球化学代理旨在解散气候和人类在冰岛土壤侵蚀史上的作用。该项目有助于启动一名早期职业拉丁裔科学家，在挪威的DNA实验室中为最近的博士提供国际博士学位，并支持一名新的博士生，并支持和指导有动机的本科生，这些学生在高度相关领域获得了研究经验。随着嵌入式记者将这项研究的气候变化传达给更广泛的公众的潜在影响。技术描述：目前，北极的变暖是全球平均水平的两倍，预计到2100年，夏季温度预计将高于20世纪后期的平均水平为4至6度。北极的放大变暖预计将导致木本植物向北移动。木质植被的增加将减少表面反照率并增加大气水蒸气，正气模型中目前受到限制的积极反馈机制。在冰岛，分层，牢固的湖泊沉积物记录跨越了当前的冰川（全新世），并包含丰富的沉积物古代DNA（Sedadna）和脂质生物标志物温度（BRGDGTS），水文学（Delta2-Hwax）和人类机构（Human Agency（fecal Sterols and Pahs））。对现代土壤和湖面沉积物网络的分析将提供校准，从而增强社区对这些有希望的新分子代理的理解，并促进区域训练集的发展。将局部校准与湖泊沉积物中的类似测量值合并，并在湖泊沉积物中分层，将实现对过去生态系统的可靠重建及其对夏季温度和氢化气候的依赖。这些数据集的新颖集成将为冰岛的早期全新世提供变化的新见解，相对于今天的早期全新世，2）何时以及到达木本植物在全新世早期温暖期间建立了哪些高度，以及3）在多大程度上，火山和/或北欧沉降在多大程度上导致了整个冰层的土壤侵蚀，如今遍布冰岛的广泛土壤。该项目的预期结果提供了为政策提供信息并改善快速变暖北极的预测所需的关键数据集。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响审查标准，认为值得通过评估来获得支持。

项目成果

Holocene history of landscape instability in Iceland: Can we deconvolve the impacts of climate, volcanism and human activity?

• DOI: 10.1016/j.quascirev.2020.106633
• 发表时间: 2020-12
• 期刊: Quaternary Science Reviews
• 影响因子: 4
• 作者: Á. Geirsdóttir;David J. Harning;G. Miller;J. Andrews;Y. Zhong;C. Caseldine