"Collaborative Research: Atmospheric Dust as an Archive and Agent of Climate Change During the Late Paleozoic Icehouse"

合作研究：大气尘埃作为晚古生代冰库期间气候变化的档案和媒介Gerilyn Soreghan，Michael Soreghan，俄克拉荷马州大学Ear-0746042 Vadimir Davydov，博伊西州立大学，Ear-0746107 Natalie Mahowald，康奈尔大学，Ear-0745961 Timothy W.里昂，大学加州，滨江，芝加哥-0745602摘要大气尘埃档案和驱动气候变化。保存在海洋和大陆沉积物和冰中的尘埃揭示了最近的气候变化，尘埃还通过直接和间接影响地球表面接收的太阳能数量以及通过刺激初级生产力从而刺激碳循环的施肥来影响气候。然而，气溶胶效应的特征和大小仍然是气候模式中约束较差的变量，从而限制了这些模式的预测能力。在这项研究中，PI建议通过调查地球上一个特别多尘的地质记录来评估“灰尘效应”。3亿年前的晚古生代世界非常多尘，尘埃通量在百万年和千年尺度上都有变化。这段时间也很有吸引力，因为上一次地球的气候类似于今天的气候，有着巨大的极地冰盖。在这里，PI建议测试的总体假设，丰富的灰尘发挥了重要作用，在晚古生代气候和相关的（如生物）系统的变化，通过直接，间接和反馈效应。他们将研究冰川和间冰期之间的灰尘通量，大气环流和灰尘运输如何变化，灰尘如何迫使热带气候发生变化，以及生物圈如何应对如此高的大气尘埃。为了解决这些问题，PI将目标锁定在热带地区的两个时间段。他们将研究尘埃分布，评估大气尘埃和风力和风向，并利用地球化学来研究对海洋生物的影响。他们将使用化石和放射性同位素测年法在不同地点之间进行关联。PI将使用他们收集的数据作为气候和灰尘建模实验的输入，以评估灰尘对大气行为的直接和间接影响，并进行生物地球化学建模，旨在评估可变养分通量对碳循环的影响。智力价值-这项研究的结果将提供一个高分辨率的热带气候重建，并揭示灰尘对气候和生活在一个世界的影响，其特点是可变的灰尘通量在不同的时间尺度上，在一个'冰川'的世界像今天的。由于尘埃和相关气溶胶在气候系统中的作用的已知重要性，但仍然存在不确定性，我们的数据将在扩大我们对整个地质时期地球系统行为的理解方面具有预测效用，并将为改善气候建模提供重要的约束条件。更广泛的影响-该项目将涉及大量学生参与（研究生和本科生水平），地质学家、地球化学家和气候建模者之间的跨学科培训，包括实地和实验室培训。本科生（地质学和教育专业）和少数民族中学生将通过辅导计划参加。将利用新开发的网络访问工具对数据进行存档和共享。最后，我们将使用这项研究的结果，以指导发展的“古生代尘暴”与自然历史的俄克拉荷马州博物馆的旅游展览，并将结果在博物馆教授的推广课程（由合作PI）。

COLLABORATIVE RESEARCH: Atmospheric Dust as an Archive and Agent of Climate Change During the Late Paleozoic Icehouse Gerilyn Soreghan, Michael Soreghan, University of Oklahoma Ear-0746042 Vadimir Davydov, Boise State University, EAR-0746107 Natalie Mahowald, Cornell University, EAR-0745961 Timothy W. Lyons, Univ. California, Riverside, EAR-0745602 Abstract Atmospheric dust archives and drives climate change. Dust preserved in marine and continental sediments and ice has shed light on recent climate change, and dust also impacts climate via direct and indirect effects on the amount of solar energy received at Earth's surface, and by fertilization that stimulates primary productivity and thus the carbon cycle. However, the character and magnitude of the aerosol effect remains a poorly constrained variable in climate models, thus limiting the predictive capability of these models. In this research, PIs propose to assess the 'dust effect' by investigating the geologic record of a particularly dusty interval on Earth. The late Paleozoic world, 300 million years ago, was remarkably dusty, with dust flux varying on both million-year and millennial scales. This time period is also attractive as the last time that Earth's climate was analogous to today's, with large polar ice sheets. Here, PIs propose to test the overarching hypothesis that the abundant dust played a significant role in driving changes in late Paleozoic climate and linked (e.g. biotic) systems, through direct, indirect, and feedback effects. They will investigate how dust flux, atmospheric circulation, and dust transport varied between glacials and interglacials, how dust forced changes in tropical climate, and how the biosphere responded to such high atmospheric dustiness. To address these questions, PIs are targeting two time slices in localities spanning the girth of the tropics. They will examine dust distribution, assess atmospheric dustiness and wind strength and direction, and use geochemistry to examine effects on marine life. They will correlate among localities using fossils and radioisotopic dating. PIs will use the data they collect as input for climate- and dust-modeling experiments, to assess the direct and indirect effects of dust on atmospheric behavior and undertake biogeochemical modeling aimed at assessing the impact of variable nutrient fluxes on cycling of carbon. Intellectual Merit-- Results of this research will provide a high-resolution reconstruction of climate for the tropics and reveal the effects of dust on climate and life in a world characterized by variable dust flux on various timescales, within a 'glacial' world like today's. Owing to the known importance but remaining uncertainty of the roles of dust and associated aerosols in the climate system, our data will have predictive utility in expanding our understanding of Earth-system behavior across geologic time, and will provide important constraints useful for improving climate modeling. Broader Impacts--This project will involve heavy student participation (graduate and undergraduate levels), cross-disciplinary training among geologists, geochemists, and climate modelers, both in the field and laboratory. Undergraduates (geology and education majors) and minority middle-schoolers will take part through mentoring programs. Data will be archived and shared using newly developed web-accessible tools. Finally, we will use results of this research to guide the development of a traveling exhibit on the 'Paleozoic Dust Bowl' in conjunction with the Oklahoma Museum of Natural History and incorporate results in an outreach course taught (by co-PIs) at the Museum.