Collaborative Research: Window into the World with 40,000-year Glacial Cycles from Climate Records in Million Year-old Ice from the Allan Hills Blue Ice Area

合作研究：通过艾伦山蓝冰区百万年冰层的气候记录了解 40,000 年冰川循环的世界之窗

• 批准号: 1443263
• 负责人: John Higgins
• 金额: $ 57.62万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1443263&HistoricalAwards=false
• 关键词: Collaborative; Research; Window; into; World

Bubbles of ancient air trapped in ice cores permit the direct reconstruction of atmospheric composition and allow us to link greenhouse gases 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 date to one million years, the oldest ice cores yet recovered from Antarctica. These records have revealed that interglacial CO2 concentrations decreased by 800,000 years ago and that, in the warmer world 1 million years ago, CO2 and Antarctic temperature were linked as during the last 800,000 years. This project will return to the Allan Hills blue ice area to recover additional ice cores that date to 1 million years or older. The climate records developed from the drilled 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. Our results will help answer questions about issues associated with anthropogenic change. These include the relationship between temperature change and the mass balance of Antarctic ice; precipitation and aridity variations associated with radiatively forced climate change; and the climate significance of sea ice extent. The project will entrain two graduate students and a postdoctoral scholar, and will conduct outreach including workshops to engage teachers in carbon science and ice cores.Between about 2.8-0.9 million years ago, Earth's climate was characterized by 40,000-year cycles, driven or paced by changes in the tilt of Earth's spin axis. Much is known about the "40,000-year" world from studies of deep-sea sediments, but our understanding of climate change during this period is incomplete because we lack records of Antarctic climate and direct records of atmospheric greenhouse gas concentrations. We propose to address these issues by building on our recent studies of ancient ice from the Main Ice Field, Allan Hills, Antarctica. During previous field seasons we recovered ice extending, discontinuously, from 0.1-1.0 million years old. Ice was dated by measuring the 40Ar/38Ar (Argon) ratio of the trapped gases. Our discovery of million year-old ice demonstrates that there is gas-record-quality ice from the 40,000-year world in the Allan Hills Main Ice Field. We have identified two different sites, each overlying bedrock at ~ 200 m depth, that are attractive targets for coring ice dating to 1 million years and older. This project aims to core the ice at these two sites, re-occupy a previous site with million year-old ice and drill it down to the bedrock, and generate 10-20 short (~10-meter) cores in areas where our previous work and terrestrial meteorite ages suggest ancient surface ice. We plan to date the ice using the 40Ar/38Ar ages of trapped Argon. We also plan to characterize the continuity of our cores by measuring the deuterium and oxygen isotope ratios in the ice, methane, ratios of Oxygen and Argon to Nitrogen in trapped gas, the Nitrogen-15 isotope (d15N) of Nitrogen, and the Oxygen-18 isotope (d18O) of Oxygen. As the ice may be stratigraphically disturbed, these measurements will provide diagnostic properties for assessing the continuity of the ice-core records. Successful retrieval of ice older than one million years will provide the opportunity for follow-up work to measure the CO2 concentration and other properties within the ice to inform on the temperature history of the Allan Hills region, dust sources and source-area aridity, moisture sources, densification conditions, global average ocean temperature, and greenhouse gas concentrations. We will analyze the data in the context of leading hypotheses of the 40,000-year world and the Mid-Pleistocene Transition to the 100,000-year world. We expect to advance understanding of climate dynamics during these periods.

被困在冰核的古老空气的气泡可以直接重建大气成分，并使我们能够在过去80万年中将温室气体和全球气候联系起来。先前前往南极洲艾伦山蓝冰地区的野外探险已经恢复了冰芯，其历史可追溯至一百万年，这是迄今已从南极洲回收的最古老的冰核。 这些记录表明，冰2二氧化碳浓度在80万年前降低了，在100万年前，在较温暖的世界中，二氧化碳和南极温度与过去80万年前有关。 该项目将返回Allan Hills Blue Ice地区，以恢复其额外的冰芯，该冰芯的历史可追溯到100万年或以上。 与当天相比，从可比甚至更大的温暖时期，从钻孔岩心岩心开发的气候记录将为大气和南极气候的化学成分提供新的见解。 我们的结果将有助于回答有关与人为变化有关的问题的问题。这些包括温度变化与南极冰的质量平衡之间的关系；与辐射强迫气候变化相关的降水和干旱变化；以及海冰范围的气候意义。 该项目将招募两名研究生和一名博士后学者，并将进行外展活动，包括与教师参与碳科学和冰核的讲习班。在大约2.8-090万年前，地球的气候以40，000年的周期为特征，以驱动或节奏为特征。通过地球旋转轴倾斜的变化。关于深海沉积物研究的“ 40，000年”世界知之甚少，但是我们对此期间气候变化的理解是不完整的，因为我们缺乏南极气候的记录和大气温室气体浓度的直接记录。 我们建议通过基于我们最近从南极洲艾伦山（Allan Hills）对古代冰场进行的研究来解决这些问题。在以前的赛季中，我们不足以恢复冰，从0.1-1万年的历史不足。冰是通过测量被困气体的40AR/38AR（氩气）比的日期。我们对百万年历史的冰的发现表明，艾伦山（Allan Hills）主冰场（Allan Hills Main Ice Field）的40，000年世界中有天然气记录质量的冰。我们已经确定了两个不同的地点，每个站点的深度约为200 m，它们是可追溯到100万年及以上的冰冰的有吸引力的靶标。该项目旨在在这两个站点上核心冰层，重新占领以前的冰冰，并将其钻至基岩，并在我们以前的以前的地区产生10-20个短（〜10米）核心工作和陆地陨石年龄表明古老的表面冰。 我们计划使用被困氩气的40AR/38AR年龄来约会冰。 我们还计划通过测量冰，甲烷，甲烷，氧气和氩气与氮的比率，氮-15同位素（D15N）以及氧气和氧气 - 氧气，氧气和氧气中的氮与氮的比率来表征核心的连续性。 18同位素（D18O）的氧气。 由于冰可能会受到地层干扰，因此这些测量值将提供诊断性能，以评估冰核记录的连续性。 成功检索超过一百万年的冰块将为测量冰2浓度和其他特性的后续工作提供机会，以告知Allan Hills地区的温度历史来源，致密条件，全球平均海洋温度和温室气体浓度。 我们将在40，000年世界的主要假设以及向中新世过渡到100，000年的世界中分析数据。我们希望在这些时期内对气候动态的理解。