Methane Isotope Variations Covering the Holocene from the WAIS Divide Core

Sowers 0944584该奖项支持一个项目，该项目旨在通过对过去11,000年(11kyr)控制大气CH4的全球生物地球化学循环的详细研究，更好地预测自然CH4排放将如何响应和迫使未来气候变化，当时地球气候一直保持相对接近其当前状态。在此期间，甲烷浓度发生了显著变化。该项目涉及使用WAIS分离冰芯的岩芯材料生成大气CH4的13C/12C同位素记录。WAIS的ä13CH4数据将被用来构建覆盖全新世的第一个南极大气记录。这一记录将与我们最近从格陵兰岛GISP2冰芯获得的全新世记录进行比较。新的南极记录将提供对GISP2记录的重要验证，以及我们第一次瞥见覆盖全新世的半球间ä13CH4梯度。这些记录一起为测试各种排放情景(时间、空间和来源)提供了重要的边界条件，这应该为评估整个全新世甲烷排放的性质提供一个量化基础。这项工作的学术价值与这样一个事实有关，即地球气候直接受到微量温室气体(二氧化碳、甲烷、一氧化二氮、氯氟化碳等)水平的影响，而这些气体在大气中的现代积累是人类社会的一个基本关切。就更广泛的影响而言，拟议的工作将加强我们对整个全新世甲烷变化模式和原因的理解。这对于理解自然气候系统，特别是气候和温室气体生物地球化学之间的反馈是重要的。全新世甲烷的记录表明，全球甲烷循环受到各种反馈的深刻影响，这些反馈不涉及大的温度波动。这意味着对相对较小的(目前未知的)强迫的强烈反馈。这项拟议的工作将有助于更好地理解甲烷水平在整个全新世发生变化的原因，为完善和测试全球模型提供基本信息。这也将有助于检验这一有争议但重要的假设，即人类从大约5000年前开始显著影响大气。本科生和研究生将参与研究的所有阶段，并将特别强调通过我们的大学教育公平办公室招收有代表性的少数民族学生。根据OPP政策，所有数据都将存档在适当的数据库中。

Sowers 0944584This award supports a project to better predict how natural CH4 emissions will respond to and force future climate change through a detailed study of the global biogeochemical cycles that control atmospheric CH4 over the past 11,000 years (11kyr), when the Earth's climate has remained relatively close to its current state. During that time, methane concentrations changed significantly. The project involves generating 13C/12C isotopic records of atmospheric CH4 using the core material from the WAIS Divide ice core. The ä13CH4 data from WAIS will be used to construct the first Antarctic atmospheric record covering the Holocene. This record will be compared to our recent Holocene record from the GISP2 ice core from Greenland. The new Antarctic record will provide an important verification of the GISP2 record as well as our first glimpse of the inter-hemispheric ä13CH4 gradient covering the Holocene. Together these records provide important boundary conditions for testing various emission scenarios (time, space and source) that should provide a quantitative basis for assessing the nature of CH4 emissions throughout the Holocene. The intellectual merit of this work relates to the fact that the earth's climate is directly influenced by levels of trace, "greenhouse" gases (carbon dioxide, methane, nitrous oxide, CFC's, and others), and the modern build up of these gases in the atmosphere is a fundamental concern for human society. In terms of broader impacts the proposed work will enhance our understanding of the patterns and causes of methane change throughout the Holocene. This is important for understanding the natural climate system, and in particular, feedbacks between climate and greenhouse gas biogeochemistry. The Holocene CH4 record suggests that the global methane cycle was profoundly influenced by various feedbacks that do not involve large temperature swings. This implies strong feedbacks to a relatively small (and presently unknown) forcing. The proposed work will lead to improved understanding of why methane levels changed throughout the Holocene, providing fundamental information to refine and test global models. It will also contribute to testing the controversial, but important, hypothesis, that humans impacted the atmosphere significantly starting about 5000 years ago. Undergraduate and graduate students will participate in all phases of the research and a special emphasis will be placed on recruiting under represented minority students thru our college based office of educational equity. All data will be archived on appropriate databases per OPP policies.