COLLABORATIVE RESEARCH: Tracing Greenhouse to Icehouse Climate Evolution Along the Western North Atlantic Meridional and Paleodepth Transect

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项目编号	1656960
	COLLABORATIVE RESEARCH: Tracing Greenhouse to Icehouse Climate Evolution Along the Western North Atlantic Meridional and Paleodepth Transect
	Mitchell Lyle
主持机构	Oregon State University
项目开始年	2017
	2017-09-15
项目结束日期	2019-08-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	64398(USD)
国家	美国
语种	英语
英文摘要	Earth's climate has changed dramatically in the last 65 million years, from a warm Eocene "greenhouse world" in which the polar regions were temperate and ice-free, to the cold "icehouse world" where glaciers periodically advanced to the mid-latitudes. Solar energy received by the earth has changed little in that time period, so variations internal to the earth system have caused the majority of the observed climate change. Position of continents, changes in ocean currents, and changes in the carbon cycle that affect the atmospheric level of greenhouse gases have all played important roles to in the evolution of Earth's climate. Oceanographic variability in the North Atlantic Ocean has been an important factor for causing periodic large glaciations in the Pleistocene, and the North Atlantic is also hypothesized to be an important climate driver under warmer climate regimes millions of years ago. The research team has designed a site survey to locate targets for collecting sediment sections from the Western North Atlantic under the auspices of the International Ocean Discovery Program (IODP). The seismic reflection survey and sediment records will be used study in detail how the ocean has changed over the last 60 million years, including documenting changes in ocean temperature, deep water flow, and greenhouse gas levels in pre-Pleistocene warm intervals. The records will also be used to better understand how continental configurations and greenhouse gases functioned in tandem to stabilize warm climates. Studying pre-Pleistocene climates will also help scientists understand processes that are likely to affect climate sensitivity in the future. Safe scientific drilling requires high-quality sub-seafloor imaging to identify suitable drill sites. The centerpiece of this project is a 31-day multichannel seismic survey using the Scripps portable high-resolution seismic system. The survey will consist of digital seismic reflection profile acquisition and multibeam mapping at each proposed drill site. These data will not only provide required data for drilling, but also will produce seismic images of changing sediment distribution as sources of deep-water production change through time. Digital seismic reflection profiles will tie the new proposed sites to existing DSDP drill sites to replace poor quality analog seismic data now available. The project will also include a reconnaissance study of Miocene change from legacy DSDP cores in the North Atlantic with well-constrained magnetic reversal stratigraphy to compare evidence for production of Northern Component Water with changes in sea surface temperature gradients, CaCO3 dissolution, and biogenic production. This builds on recent observations that cooling during the middle to late Miocene was delayed in the very high northern latitudes relative to cooling of the deep sea and southern ocean, and will test the hypothesis that cooling was diachronous across latitudes. The IODP drilling will eventually provide continuous Eocene-Holocene sedimentary records that resolve orbital periodicities to compare to similar records from the Pacific. The project supports graduate student training at Rutgers University, and provides sea going experiences for additional graduate students through a "co-chief scientist in training" program.
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文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/71970
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Mitchell Lyle.COLLABORATIVE RESEARCH: Tracing Greenhouse to Icehouse Climate Evolution Along the Western North Atlantic Meridional and Paleodepth Transect.2017.