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P2C2: Collaborative Research: New Estimates of Atmospheric pCO2 for the Paleocene-Eocene

P2C2：合作研究：古新世-始新世大气 pCO2 的新估计

基本信息

批准号：
1805228
负责人：
Richard Barclay
金额：
$ 67.12万
依托单位：
Smithsonian Institution
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：
2018-05-01 至 2022-09-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1805228&HistoricalAwards=false
关键词：
P2C2 Collaborative Research New Estimates

项目摘要

How global temperature responds to changes in atmospheric carbon dioxide is a central question in Earth science with enormous societal significance. The deep-time history of carbon dioxide in Earth's atmosphere may help us quantify the role of this greenhouse gas in abrupt climate change events in the geological past, giving a better perspective towards climate projections under future scenarios of increasing atmospheric carbon dioxide. This project will refine proxy estimates of atmospheric carbon dioxide that are based on an understanding of how the properties of stomatal pores in the leaves of Ginkgo trees respond to elevated carbon dioxide concentration. This proxy relationship, established using controlled experiments on cultivated Ginkgo leaves, will then be applied to the ancient record of atmospheric carbon dioxide using fossil Ginkgo leaves that are common in sediments deposited during periods when Earth's atmospheric carbon dioxide concentration and climate varied substantially. These more precise estimates of ancient atmospheric carbon dioxide will thus help to refine our understanding of the sensitivity of Earth's climate system to greenhouse gas concentrations and facilitate more accurate projections of changes in climate, ice volume and sea level that will result from anthropogenic carbon dioxide emissions. More accurate projections of these future scenarios will have significant societal and economic implications for infrastructure and food production. The project will also educate students and citizen scientists about the scientific method and insights from this research by involving them in collecting specimens, making measurements and analyzing data.Sensitivity of global temperature to atmospheric pCO2 is difficult to determine by direct atmospheric measurements because feedbacks in the Earth system play out over millennia or longer. This research will develop a reliable, temporally dense proxy record of pCO2 for the late Paleocene and Early Eocene period of warm climates (~60-53 Ma) using stomatal properties of fossil Ginkgo leaves. The researchers will first refine a proxy relationship between Ginkgo leaf stomatal properties, and then apply this proxy to dense and temporally well-constrained fossil records of Ginkgo. To establish the response of modern Ginkgo to elevated pCO2 concentrations, trees will be cultivated under experimental conditions at three elevated CO2 concentrations in open-top chambers, while monitoring stomatal density, size and index, as well as carbon isotopic composition and rates of photosynthetic assimilation and transpiration, temperature, relative humidity, and photosynthetically active radiation. These data from experimental cultivation will be used along with survey data of modern Ginkgo leaves, to allow the researchers to evaluate modeled relationships between paleo-pCO2 and fossil stomata. Once this response is calibrated for modern Ginkgo biloba, the results will be applied to extensive collections of fossil Ginkgo wyomingensis from the terrestrial sediments of the Paleogene in the Rocky Mountains. This record, combined with records of paleotemperature from the marine and terrestrial realms will be used to evaluate the role of atmospheric CO2 during episodes of geologically rapid temperature increases (hyperthermals). Better estimates of paleo-pCO2 will contribute substantially to refining our understanding of Earth's climate sensitivity to carbon dioxide and increase our understanding of controls on past warm climates in the geological record.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.

全球温度如何响应大气中二氧化碳的变化是地球科学中具有巨大社会意义的中心问题。地球大气中二氧化碳的深时历史可能有助于我们量化这种温室气体在地质历史中的气候突变事件中的作用，从而更好地了解未来大气二氧化碳增加情景下的气候预测。该项目将完善大气二氧化碳的替代估计，该估计是基于对银杏树叶片气孔特性如何响应二氧化碳浓度升高的理解。这种替代关系，建立了对栽培银杏叶的控制实验，然后将被应用到大气二氧化碳的古代记录，使用化石银杏叶是常见的沉积物中沉积的时期，地球的大气二氧化碳浓度和气候变化很大。因此，对古代大气二氧化碳的这些更精确的估计将有助于我们更好地了解地球气候系统对温室气体浓度的敏感性，并有助于更准确地预测人类二氧化碳排放将导致的气候、冰量和海平面的变化。对这些未来情景的更准确预测将对基础设施和粮食生产产生重大的社会和经济影响。该项目还将通过让学生和公民科学家参与收集标本、进行测量和分析数据，向他们传授这项研究的科学方法和见解。全球温度对大气pCO 2的敏感性很难通过直接大气测量来确定，因为地球系统中的反馈会持续数千年或更长时间。这项研究将开发一个可靠的，时间密集的代理记录pCO 2的古新世晚期和始新世早期的温暖气候（~60-53 Ma）使用化石银杏叶的气孔特性。研究人员将首先完善银杏叶气孔特性之间的代理关系，然后将此代理应用于银杏的密集和时间约束良好的化石记录。为了建立现代银杏pCO 2浓度升高的反应，树木将在实验条件下培养在三个高CO2浓度在开顶式商会，同时监测气孔密度，大小和指数，以及碳同位素组成和光合同化和蒸腾速率，温度，相对湿度和光合有效辐射。这些来自实验栽培的数据将与现代银杏叶的调查数据一起沿着使用，以使研究人员能够评估古pCO 2和化石气孔之间的模型关系。一旦这个响应是校准现代银杏，结果将被应用到广泛收集的化石银杏wyomingensis从陆地沉积物的古近纪在落基山脉。这一记录与海洋和陆地的古温度记录相结合，将用于评估地质学上温度迅速上升（高温）期间大气中二氧化碳的作用。更好地估计pCO 2将大大有助于完善我们对地球气候对二氧化碳敏感性的理解，并增加我们对地质记录中过去温暖气候控制的理解。该奖项反映了NSF的法定使命，并被认为值得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来支持。