A Northern Hemisphere Holocene Paleoatmospheric Record of Ethane and Acetylene from the GISP2 Ice Core

由于温室气体和气溶胶的排放，生物质燃烧对大气成分和气候产生重大影响。过去火灾排放的历史没有很好的记录，因此，火灾与气候在长时间尺度上的关系还没有得到很好的理解。该项目将调查乙烷和乙炔的大气历史，这是由生物质和生物燃料燃烧排放到大气中的微量气体。对格陵兰冰芯中气泡中这些微量气体的测量将记录这些微量气体在大范围气候条件和环境变化下大气水平的过去变化。这些数据将为千禧年时间尺度上的火灾变异性提供新的见解，并量化火灾对过去大气温室气体水平的贡献。这些知识将有助于开发能够在未来气候情景中模拟火灾的陆地表面和地球系统模式。该项目将支持加州大学欧文分校地球系统科学系一名博士生的论文研究，并通过加州大学欧文分校研究生创立和运营的非营利性清洁教育计划在K-12教室开展推广活动。在坚硬的空气和浅冰芯中对乙烷和乙炔的测量表明，极地冰中捕获的空气中含有这些微量气体的古大气记录。在这项研究中，研究人员将分析来自格陵兰岛Summit的GISP2冰芯样本中的乙烷和乙炔，该冰芯跨越末次极大期、冰期/间冰期过渡和全新世。将利用三维全球光化学/输运模式和生物地球化学盒模式从大气历史中推断出微量气体排放。这项研究将提供北半球与正在开发的南极冰芯记录相对应的记录。总之，格陵兰和南极的记录将提供以下估计：1)过去全球生物质燃烧排放的这些微量气体，2)热带和北方源之间的火灾排放的划分，以及3)热源甲烷排放的幅度和变化。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

Biomass burning has a major impact on atmospheric composition and climate due to emissions of greenhouse gases and aerosols. The past history of fire emissions is not well documented, and as a result, the relationship between fire and climate on long time scales is not well understood. This project will investigate the atmospheric histories of ethane and acetylene, trace gases emitted to the atmosphere from biomass and biofuel burning. Measurements of these trace gases in the air bubbles entrapped in Greenland ice cores will document past variations in the atmospheric levels of these trace gases over a wide range of climatic conditions and environmental change. The data will provide new insight into the variability in fire on millennial time scales and quantify the contribution of fire to past atmospheric levels of greenhouse gases. This knowledge will contribute to the development of land surface and earth system models capable of simulating fire in future climate scenarios. This project will support the dissertation research of a PhD student in the UC Irvine Department of Earth System Science and outreach activities in K-12 classrooms through the non-profit CLEAN Education initiative founded and operated by graduate students at UC Irvine. Ethane and acetylene measurements in firn air and shallow ice cores demonstrate that the entrapped air in polar ice contains a paleoatmospheric record of these trace gases. In this study, the investigators will analyze ethane and acetylene in ice core samples from the GISP2 ice core (Summit, Greenland), spanning the last glacial maximum, glacial/interglacial transition, and Holocene periods. Trace gas emissions will be inferred from the atmospheric histories using a 3-D global photochemical/transport model and biogeochemical box models. This study will provide a northern hemispheric counterpart to an Antarctic ice core record under development. Together, the Greenland and Antarctic records will provide estimates of: 1) past global biomass burning emissions of these trace gases, 2) partitioning of fire emissions between tropical and boreal sources, and 3) the magnitude and variability of pyrogenic methane emissions.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.