Collaborative Research: Snapshots of Early and Mid-Pleistocene Climate and Atmospheric Composition from the Allan Hills Blue Ice Area

合作研究：艾伦山蓝冰区早更新世和中更新世气候和大气成分的快照

• 批准号: 1744993
• 负责人: John Higgins
• 金额: $ 105.53万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-15 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744993&HistoricalAwards=false
• 关键词: Collaborative; Research; Snapshots; Early; Mid

Bubbles of ancient air trapped in ice cores have been used to directly reconstruct atmospheric composition, and its links to Antarctic and global climate, over the last 800,000 years. Previous field expeditions to the Allan Hills Blue Ice Area, Antarctica, have recovered ice cores that extend as far back as 2.7 million years, by far the oldest polar ice samples yet recovered. These ice cores extend direct observations of atmospheric carbon dioxide and methane concentrations and indirect records of Antarctic climate into a period of Earth's climate history that represents a plausible geologic analogue to future anthropogenic climate change. The results demonstrate a smaller glacial-interglacial variability of climate and greenhouse gases, and a persistent linkage between Antarctic climate and atmospheric carbon dioxide, between 1 and 2 million years ago. Through this project, the team will return to the Allan Hills Blue Ice Area to recover additional ice cores that date to 2 million years or older. The climate records developed from these ice cores will provide new insights into the chemical composition of the atmosphere and Antarctic climate during times of comparable or even greater warmth than the present day. Project results will help answer questions about issues associated with anthropogenic change including the relationship between temperature change and the mass balance of Antarctic ice and the relationship between atmospheric greenhouse gases and global climate change. Earth has been cooling, and ice sheets expanding, over the past ~52 million years. Superimposed on this cooling are periodic changes in Earth's climate system driven by variations in the eccentricity, precession, and obliquity of Earth's orbit around the Sun. Climate reconstructions based on measurements of oxygen isotopes in foraminiferal calcite indicate that, from ~2.8 to 1.2 million years before present (Ma), Earth's climate system oscillated between glacial and interglacial states every ~40,000 years (the "40k world"). Between 1.2-0.8 Ma and continuing to the present, the period of glacial cycles increased in amplitude and lengthened to ~100,000 years (the "100k world"). Ice cores preserve ancient air that allows direct reconstructions of atmospheric carbon dioxide and methane. They also archive proxy records of regional climate, mean ocean temperature, global oxygen cycling, and the aridity of nearby continents. Studies of stratigraphically continuous ice cores, extending to 800,000 years before present, have demonstrated that atmospheric carbon dioxide is strongly linked to climate, and it is of great interest to extend the ice-core record into the 40k world. Recent discoveries of well-preserved ice dating from 1.0 to 2.7 Ma from ice cores drilled in the Allan Hills Blue Ice Area (BIA), Antarctica, demonstrate the potential to retrieve stratigraphically discontinuous old ice at shallow depths (200 meters). This project will continue this work by retrieving new large-volume ice cores and measuring paleoclimate properties in both new and existing ice from the Allan Hills BIA. The experimental objectives are to more fully characterize fundamental properties of the climate system and the carbon cycle during the 40k world. Project results will have implications for Pleistocene climate change, and will provide new constraints on the processes that regulate atmospheric carbon dioxide, methane, and oxygen on geologic timescales. Given a demonstrated age of the ice at the Allan Hills BIA of at least 2 million years, the team will drill additional cores to prospect for ice that predates the initiation of Northern Hemisphere glaciation at the Plio-Pleistocene transition (~2.8 Ma).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.

在过去的800，000年中，被困在冰核中的古老空气的气泡已被用来直接重建大气成分，并与南极和全球气候的联系。先前前往艾伦山（Allan Hills）蓝冰区（南极洲）进行的野外探险已经恢复了冰芯，该冰芯延伸至270万年，这是迄今为止最古老的极地冰样品。 这些冰核直接观察到大气二氧化碳和甲烷浓度以及南极气候的间接记录到地球气候历史的时期，代表了对未来人为气候变化的合理地质类似物。结果表明，在1到200万年前，气候和温室气体气候和温室气体的变化较小，南极气候与大气二氧化碳之间的持续联系。通过这个项目，团队将返回艾伦山蓝冰区，以追回约200万年或以上的额外的冰芯。 这些冰核心发展的气候记录将在可比甚至更大的温暖时期对大气和南极气候的化学成分提供新的见解。 项目结果将有助于回答有关与人为变化相关的问题的问题，包括温度变化与南极冰的质量平衡之间的关系以及大气温室气体与全球气候变化之间的关系。在过去的5200万年中，地球一直在冷却，冰盖膨胀。在这种冷却下叠加的是地球气候系统的周期性变化，这是由于地球围绕太阳的偏心，进攻和倾斜度的变化所驱动的。基于有孔虫方解石中氧同位素的测量的气候重建表明，在目前（MA）之前约2.8至120万年（MA），地球的气候系统每〜40,000年之间在冰川状态和冰川间国家之间振荡（“ 40k World”）。在1.2-0.8 Ma之间，并继续到现在，冰川周期的幅度增加并延长至约100，000年（“ 100k世界”）。冰芯保存古老的空气，可直接重建大气二氧化碳和甲烷。他们还存档了区域气候，平均海洋温度，全球氧气循环以及附近大陆的干旱的代理记录。对地层连续的冰核的研究延长了至800,000年，这表明大气中的二氧化碳与气候密切相关，并且将冰核记录扩展到40k世界是引起极大的兴趣。在南极洲的Allan Hills Blue Ice区（BIA）中钻出的冰芯的最新发现可追溯到1.0至2.7 MA，这表明有可能在浅层深度（200米）检索地层不连续的旧冰（200米）。该项目将通过检索新的大容量冰芯并测量Allan Hills Bia的新冰和现有冰的古气候特性来继续这项工作。实验目标是更充分地表征40k世界中气候系统和碳循环的基本特性。项目结果将对更新世的气候变化有影响，并将对调节地质时间尺度上调节大气二氧化碳，甲烷和氧的过程提供新的限制。鉴于在Allan Hills Bia的冰年龄至少为2000万年，该团队将在冰上进行更多的核心，该核心早于在Plio-Pleistecene过渡（〜2.8 MA）之前（〜2.8 MA）启动北半球冰川。该奖项反映了NSF的法定任务，并通过评估范围的范围来反映了对基础的支持，并已被评估范围众所周知。

项目成果

Two-million-year-old snapshots of atmospheric gases from Antarctic ice

• DOI: 10.1038/s41586-019-1692-3
• 发表时间: 2019-10
• 期刊: Nature
• 影响因子: 64.8
• 作者: Yuzhen Yan;M. Bender;E. Brook;H. Clifford;P. Kemeny;A. Kurbatov;Sean L. Mackay;P. Mayewski;J. Ng;J. Severinghaus;J. Higgins

Early Pleistocene East Antarctic temperature in phase with local insolation

早更新世南极东部温度与局部日照同步

• DOI: 10.1038/s41561-022-01095-x
• 发表时间: 2022
• 期刊: Nature Geoscience
• 影响因子: 18.3
• 作者: Yan, Yuzhen;Kurbatov, Andrei V.;Mayewski, Paul A.;Shackleton, Sarah;Higgins, John A.
• 通讯作者: Higgins, John A.