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

GSTDTAP

项目编号	1804974
	Collaborative Research: New Estimates of Atmospheric pCO2 from the Paleocene-Eocene
	Jonathan Wilson
主持机构	Haverford College
项目开始年	2018
	2018-05-01
项目结束日期	2021-04-30
资助机构	US-NSF
项目类别	Continuing grant
项目经费	38960(USD)
国家	美国
语种	英语
英文摘要	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.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/72529
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Jonathan Wilson.Collaborative Research: New Estimates of Atmospheric pCO2 from the Paleocene-Eocene.2018.