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

合作研究：追踪北大西洋西部经向和古深度横断面从温室到冰库的气候演变

• 批准号: 1657013
• 负责人: Kenneth Miller
• 金额: $ 31.28万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-15 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1657013&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Tracing; Greenhouse; Icehouse

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.

在过去的6500万年中，地球的气候发生了巨大变化，从始新世的“温室世界”中，极地地区是温带和无冰的，再到冰川世界冰川定期前进到中期的冰冷的“冰屋世界”。在那个时期，地球收到的太阳能几乎没有变化，因此地球系统内部的变化导致了大​​部分观察到的气候变化。大陆的位置，洋流的变化以及影响大气温室气体水平的碳循环的变化在地球气候的演变中都起着重要作用。北大西洋的海洋变异性一直是引起更新世周期性大冰川的重要因素，在数百万年前，在温暖的气候状态下，北大西洋也是重要的气候驱动因素。研究小组设计了一项现场调查，以定位在国际海洋发现计划（IODP）主持下从北大西洋西部收集沉积物部分的目标。地震反射调查和沉积物记录将详细研究在过去的6000万年中，海洋如何变化，包括记录海洋温度，深水流量和温室气体水平的变化。这些记录还将用于更好地了解大陆构型和温室气体如何串联起作用以稳定温暖的气候。研究新世气候还将帮助科学家了解未来可能影响气候敏感性的过程。安全的科学钻探需要高质量的下层状成像来识别合适的钻头。该项目的核心是使用Scripps Portable高分辨率地震系统进行的31天多通道地震调查。该调查将包括在每个拟议的钻井场所的数字地震反射曲线采集和多光束映射。这些数据不仅将提供钻孔所需的数据，而且还将产生变化的沉积物分布的地震图像，因为深水生产的来源会随着时间的流逝而变化。数字地震反射概况将把新提出的站点与现有的DSDP钻头相关联，以取代现已可用的质量质量模拟地震数据。该项目还将包括对北大西洋传统DSDP核心的中新世变化的侦察研究，并具有良好的磁反转地层学，以比较生产北部组件水与海面温度梯度的变化，CACO3溶解和生物产生的证据。这是基于最近的观察结果，即中新世中期至后期的冷却在非常高的北纬度地区相对于深海和南大洋的冷却而被推迟，并将检验假设在纬度跨纬度的冷却是历时性的假设。 IODP钻探最终将提供连续的始新世沉积记录，以解决轨道周期性与太平洋的类似记录进行比较。该项目支持罗格斯大学的研究生培训，并通过“培训联合首席科学家”计划为其他研究生提供海上经验。