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

大气尘埃：晚古生代冰库时期气候变化的档案与驱动因素Gerilyn Soreghan， Michael Soreghan，俄克拉何马大学vladimir Davydov，博伊西州立大学，EAR-0746107 Natalie Mahowald，康奈尔大学，EAR-0745961 Timothy W. Lyons，加州大学河滨分校，EAR-0745602摘要大气尘埃档案与驱动气候变化。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量，以及通过刺激初级生产力从而促进碳循环的施肥来影响气候。然而，在气候模式中，气溶胶效应的特征和大小仍然是一个约束较差的变量，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区间的地质记录来评估“尘埃效应”。3亿年前，古生代晚期的世界尘土飞扬，尘埃通量在百万年和千年的尺度上都在变化。这个时期也很有吸引力，因为地球的气候最后一次类似于今天，有巨大的极地冰盖。在这里，PIs建议测试一个总体假设，即丰富的尘埃在推动晚古生代气候和相关（如生物）系统的变化中发挥了重要作用，通过直接、间接和反馈效应。他们将研究沙尘通量、大气环流和沙尘运输在冰期和间冰期之间是如何变化的，沙尘是如何迫使热带气候发生变化的，以及生物圈是如何对如此高的大气含沙量做出反应的。为了解决这些问题，pi瞄准了横跨热带地区的两个时间片。他们将检查尘埃分布，评估大气尘埃浓度和风的强度和方向，并利用地球化学来检查对海洋生物的影响。他们将利用化石和放射性同位素定年来确定不同地点之间的关系。各项目将利用它们收集的数据作为气候和粉尘模拟实验的输入，评估粉尘对大气行为的直接和间接影响，并进行生物地球化学模拟，以评估各种养分通量对碳循环的影响。知识价值——这项研究的结果将提供热带气候的高分辨率重建，并揭示在一个以不同时间尺度上的可变尘埃通量为特征的世界中，在像今天这样的“冰川”世界中，尘埃对气候和生命的影响。由于已知尘埃和相关气溶胶在气候系统中的作用的重要性，但仍然存在不确定性，我们的数据将在扩展我们对地质时期地球系统行为的理解方面具有预测效用，并将为改进气候模型提供有用的重要约束。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师在实地和实验室进行跨学科培训。大学生（地质教育专业）和少数民族中学生将通过辅导项目参加。数据将通过新开发的网络工具进行存档和共享。最后，我们将利用这项研究的结果来指导与俄克拉何马州自然历史博物馆合作的“古生代沙尘暴”巡回展览的发展，并将结果纳入博物馆教授的外展课程（由合作项目负责人）。

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.