Controls on Variations in Atmospheric Carbon Dioxide and Nitrous Oxide During the Last 10,000 years

地球的温度在一定程度上是由包括二氧化碳、甲烷和一氧化二氮在内的吸热气体控制的。尽管这些气体对气候很重要，但对大气中这些气体的直接测量最多仅限于过去50年。冰芯中的空气将这些数据追溯到几十万年前，对冰芯中温室气体的测量巩固了我们对与现代气候变化有关的全球化学循环的理解。现有记录的质量和细节各不相同。这项提议的工作填补了我们在过去一万年中对一氧化二氮和二氧化碳的认识空白。来自南极冰芯的新测量结果将用于确定海洋和陆地过程的变化在控制这些气体方面所起的作用，这些气体在这个时期的前2000年减少，然后逐渐增加到现在。这项工作将解决关于早期人类活动是否可能影响大气的重大争议，并提供数据，以改进陆地-海洋-大气系统的数学模型，预测未来气候变化将如何影响大气和气候的组成。对于氧化亚氮，这项工作将改进现有的浓度记录，并提供一个新的、详细的全新世稳定同位素记录。它还将发展氧化亚氮同位素体的测量，并探索其在了解全新世氧化亚氮收支方面的效用。主要目标是确定海洋和/或陆地氧化亚氮的排放是否会随着全新世气候的变化而变化。新的全新世二氧化碳同位素记录（稳定的碳和氧同位素）将使现有记录的精度提高5倍，并增加时间分辨率。这些数据将用于评估关于为什么二氧化碳浓度在全新世发生变化的有争议的假设，并为当前同位素数据无法解决的碳循环千年尺度过程提供见解。在此期间，一名研究生将接受高级培训，学生和主要研究者将针对当地中学生开展外展工作。拟议的工作还将有助于气候研究所的教学工作以及有关气候和气候变化的公开讲座。研究结果将通过出版物、数据档案和俄勒冈州立大学冰芯实验室网站发布。还将开发和记录具有广泛用途的新分析方法。

The temperature of the earth is controlled, in part, by heat trapping gases that include carbon dioxide, methane, and nitrous oxide. Despite their importance to climate, direct measurements of these gases in the atmosphere are limited to the last 50 years at best. Air trapped in ice cores extends those data back hundreds of millennia, and measurements of greenhouse gases in ice cores underpin much of our understanding of global chemical cycles relevant to modern climate change. Existing records vary in quality and detail. The proposed work fills gaps in our knowledge of nitrous oxide and carbon dioxide over the last 10,000 years. New measurements from an ice core from the South Pole will be used to determine what role changes in ocean and land based processes played in controlling these gases, which decreased during the first 2,000 years of this time period, then gradually increased toward the present. The work will address a major controversy over whether early human activities could have impacted the atmosphere, and provide data to improve mathematical models of the land-ocean-atmosphere system that predict how future climate change will impact the composition of the atmosphere and climate. For nitrous oxide the work will improve on existing concentration records and provide a novel, detailed Holocene stable isotope record. It will also develop measurement of the isotopomers of nitrous oxide and explore their utility for understanding aspects of the Holocene nitrous oxide budget. The primary goal is to determine if marine and/or terrestrial emissions of nitrous oxide change in response to changes in Holocene climate. A new Holocene isotopic record for carbon dioxide (stable carbon and oxygen isotopes), will improve the precision of existing records by a factor 5 and increase the temporal resolution. These data will be used to evaluate controversial hypotheses about why carbon dioxide concentrations changed in the Holocene and provide insight into millennial scale processes in the carbon cycle, which are not resolved by current isotopic data. A graduate student will receive advanced training during and the student and principle investigator will conduct outreach efforts targeted at local middle school students. The proposed work will also contribute to teaching efforts by the PI and to public lectures on climate and climate change. The results will be disseminated through publications, data archive, and the OSU Ice Core Lab web site. New analytical methods of wide utility will also be developed and documented.