Interannual and Orbital-Scale Climate Variability in the Early Miocene: Physical, Chemical and Biological Investigations of the Foulden Maar Diatomite

早中新世的年际和轨道尺度气候变率：福尔登玛尔硅藻土的物理、化学和生物研究

• 批准号: 1349659
• 负责人: William D'Andrea
• 金额: $ 24.17万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1349659&HistoricalAwards=false
• 关键词: Interannual; Orbital; Scale; Climate; Variability

Interannual and Orbital-Scale Climate Variability in the Early Miocene: Physical, Chemical and Biological Investigations of the Foulden Maar DiatomitebyWilliam D'Andrea, Columbia University, EAR-1349659ABSTRACT(The Antarctic Earth Sciences Program (PLR) co-funded the grant with the Seimentary Geology and Paleobiology Program (EAR).Accurate climate projections for the future require a fundamental understanding of Earth's climate system and its behavior during past warm periods. Sediments that have accumulated in lakes and ocean basins are our only source for observational data to examine changes in Earth's climate in the deep past. Sediment records that accumulated over long periods of time, have annual layering and which contain natural recorders of past climate are extremely rare, but are needed to investigate inter-annual climate variability (for example, the El Niño-Southern Oscillation (ENSO)) under warmer global temperature, as well as the response of the climate system to periodic variations in Earth's orbit. Using a combination of physical and chemical sedimentological techniques, the investigators will take advantage of an exceptional sedimentary record to achieve the following goals:1) Determine the drivers of early Miocene temperature and hydrologic change at suborbital timescales using organic geochemical and stable isotopic techniques. The research will test the hypothesis that natural changes in solar energy at the equator cause variations in mid-latitude climate with a pacing of approximately 11,000 years. 2) Document the nature of ENSO variability under different orbital configurations within the warm background state of the early Miocene by developing records of annual sediment layer thickness across fourteen different 1,000-yr periods. This will test the hypothesis that ENSO transitions to a permanent El Niño-like state during periods of global warmth and will help determine how the climate system behaves in a warmer world and how orbital forcing modulates ENSO. 3) Produce a record of atmospheric CO2 concentrations (pCO2) across an extreme Antarctic glaciation event in the early Miocene using stomatal density of fossil leaves. This will provide important data to examine the role (or lack thereof) of atmospheric pCO2 in driving major climate changes during this time period. The Foulden Maar Diatomite in Otago, New Zealand is an annually layered lake-sediment sequence that was deposited during a 100,000-year period, 23 million years ago. This time period is interesting because although the planet was warmer than present, Antarctic Ice Sheets grew larger than their present size, even though there were no Northern Hemisphere Ice Sheets. Furthermore, data suggest that atmospheric pCO2 levels were similar to today. The investigators will use fossil leaves in the sediments to estimate pCO2 across this enigmatic period of Earth's past, a time when the behavior of ice sheets and global temperature is at odds with the existing pCO2 data. The thickness of the annual sediment layers is related to the productivity of algae in the lake, a parameter controlled by climate. The thickness of these layers can therefore be measured and used to examine how inter-annual climate variability (specifically, ENSO) behaved during this time period and whether it changed due to the natural changes in Earth's orbit. The researchers will determine how temperature and moisture changed over this time period using organic molecules in the sediments and will test the hypothesis that natural changes in solar energy at the equator cause variations in mid-latitude climate with an 11,000-year cycle. The results will contribute to a better understanding of the natural forcing mechanisms that impact ENSO dynamics and its influence on mid-latitude climate. The outcomes of the proposed work will contribute to the fundamental understanding of Earth's climate system, interactions among different climatic processes, and the resulting impacts on global climate.

中新世早期的年间和轨道尺度的气候变化：对哥伦比亚大学哥伦比亚大学Foulden Maar Diotomitebywilliam d'Andrea的物理，化学和生物学研究，EAR-1349659ABSTRACT（1349659ABSTRACT）（AER-1349659ABSTRACT（AERTARATIC EARTH SCIENCES PROGRANIT）与Secorment Injutions（PLR）共同基金会（PLR），以良好的态度和清理杂货学计划（ETRECARE GERISTARY GEOLOGIAC）（未来）我们的观察数据是我们唯一的观察数据来检查地球气候变化的基本理解，这是我们长时间积累的地球气候变化的来源。地球轨道周期性变化的气候结合，研究人员将利用出色的沉积记录来实现以下目标：1）确定中新世温度早期温度的驱动因素，使用有机地球和稳定的稳定时刻尺度的驱动器。这项研究将检验以下假设：等效器处太阳能的自然​​变化会导致中纬度气候的变化，其起搏约为11，000年。 2）记录在中新世早期温暖背景状态下不同轨道构型下ENSO变异性的性质，通过在14个不同的1,000年期间开发年度沉积物层厚度的记录。这将检验以下假设：在全球温暖时期，ENSO转变为永久性厄尔尼诺现状，并将有助于确定气候系统在温暖的世界中的行为以及轨道强迫调节的调制。 3）使用化石叶子的气孔密度，在中新世早期的极端南极冰川事件中产生了大气二氧化碳浓度（PCO2）的记录。这将提供重要的数据，以研究在此期间在大气中驱动重大气候变化的大气PCO2的作用（或缺乏）。新西兰奥塔哥的Foulden Maar硅藻土是一年一度的分层湖泊，在2300万年前的100，000年内存放。这个时期很有趣，因为尽管行星比现在温暖，但南极冰盖的生长比现在的大小还大，即使没有北半球冰盖。此外，数据表明大气PCO2水平与今天相似。研究人员将使用沉积物中的化石叶来估计地球过去这个神秘时期的PCO2，这是冰盖和全球温度与现有PCO2数据不一致的时期。年度沉积物层的厚度与湖中藻类的生产率有关，湖中的藻类的生产率是由气候控制的参数。因此，可以测量这些层的厚度，并用于检查在这段时间内的年度攀岩变异性（特别是ENSO）的表现，以及由于地球轨道的自然变化而变化。研究人员将使用沉积物中的有机分子来确定在这段时间内温度和水分如何变化，并将检验以下假设：在等等效器处太阳能的自然​​变化会导致中纬度的变化，而纬度攀升则以11，000年的周期攀升。结果将有助于更好地理解影响ENSO动力学及其对中纬度气候的影响的自然强迫机制。拟议工作的结果将有助于对地球气候系统的基本理解，不同的杂种过程之间的相互作用以及对全球气候的影响。