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Environmental Change and Biotic Impacts of a Transient Greenhouse Warming Event in the Middle Eocene

始新世中期短暂的温室变暖事件的环境变化和生物影响

基本信息

批准号：
NE/H016457/1
负责人：
Kirsty Edgar
金额：
$ 30.94万
依托单位：
CARDIFF UNIVERSITY
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH016457%2F1
关键词：
Environmental Change Biotic Impacts Transient

项目摘要

SUMMARY Global atmospheric carbon dioxide levels (pCO2) are rising at a rate unprecedented in Earth's history as a result of human activity. Current atmospheric pCO2 is 387 ppmv and exceeds concentrations reported for the last ~25 million years of Earth's history. To predict the future response of the Earth's system to increasing pCO2 it is imperative that we develop a better understanding of how global climate and carbon cycling has varied during high pCO2 time intervals in the past. A good analogue is the Eocene Epoch (55-34 million years ago, Myr) because it is the most geologically recent interval of sustained global warmth characterised by high pCO2 (> 1000 ppm). The research proposed focuses on a recently discovered, short-lived global warming event during the middle Eocene approximately 40 million years ago - the Middle Eocene Climatic Optimum (MECO). During this event, global temperatures rose by 4 to 6 degrees celsius and the deep ocean became more acidic, presumably as a consequence of a temporary increase in atmospheric pCO2. This event is particularly interesting because the timing and cause of the MECO differ from other warming events reported in the Eocene. However, we know very little about the environmental changes that accompanied this unique event and the associated impacts. For example - How sensitive is the climate to pCO2 change? How did Earth's biota respond to shifts in climate? These questions can be addressed by measuring the geochemical composition of microfossils that are found in marine sediments. In this study, novel geochemical analyses of two different types of microfossil: foraminifera (single-celled organisms that build their shell from calcium carbonate) and fossil fish teeth, will be used to reconstruct past environmental variables. Chemical analysis of planktonic foraminiferal shells will be used to reconstruct changes in sea surface temperature and acidity during the MECO event. The response of planktonic foraminifera, e.g., number of species, amount of each species and shell size, will also be recorded to assess any links between surface water changes and the response of the biota. Contemporaneous changes in bottom water conditions e.g., temperature and oxygen concentration, will also be assessed by analysing the geochemical composition of benthic foraminiferal shells and fossil fish teeth. Ultimately, study of past global warming events, such as the MECO, will provide a greater understanding of the links between pCO2 and global climate, which is essential to understanding Earth system behaviour. This work will provide new insights into the operation of the carbon cycle in a high pCO2 world and produce key data for the configuration and testing of numerical palaeoclimate and carbon cycle models. The research will be based within the School of Earth and Ocean Sciences at the University of Cardiff, which is actively investigating critical intervals of climate change in the geological past. I will also collaborate with scientists from other institutes notably, the National Oceanography Centre, Southampton and the University of South Carolina (see partnership details).

由于人类活动，全球大气二氧化碳水平（pCO 2）正在以地球历史上前所未有的速度上升。目前大气pCO 2为387 ppmv，超过了地球历史上最后2500万年的浓度。为了预测地球系统对增加pCO 2的未来反应，我们必须更好地了解过去在高pCO 2时间间隔内全球气候和碳循环是如何变化的。一个很好的类比是始新世（5500 - 3400万年前，Myr），因为它是地质学上最新的持续全球变暖时期，其特征是高pCO 2（> 1000 ppm）。这项研究的重点是最近发现的，大约4000万年前始新世中期短暂的全球变暖事件-始新世中期气候适宜期（MECO）。在这一事件中，全球气温上升了4至6摄氏度，深海变得更加酸性，可能是大气pCO 2暂时增加的结果。这一事件特别有趣，因为MECO的时间和原因与始新世报告的其他变暖事件不同。然而，我们对伴随这一独特事件的环境变化及其相关影响知之甚少。气候对pCO 2变化的敏感程度如何？地球生物群如何应对气候变化？这些问题可以通过测量海洋沉积物中发现的微体化石的地球化学成分来解决。在这项研究中，两种不同类型的微体化石的新的地球化学分析：有孔虫（单细胞生物，从碳酸钙建立他们的外壳）和化石鱼牙齿，将被用来重建过去的环境变量。对南极有孔虫壳的化学分析将用于重建MECO事件期间海洋表面温度和酸度的变化。浮游有孔虫的反应，例如，还将记录物种数量、每个物种的数量和贝壳大小，以评估地表水变化与生物群反应之间的联系。底层水条件的同期变化，例如，还将通过分析底栖有孔虫壳和鱼牙齿化石的地球化学成分，评估温度和氧气浓度。最终，对过去全球变暖事件（如MECO）的研究将更好地了解pCO 2与全球气候之间的联系，这对了解地球系统行为至关重要。这项工作将为高pCO 2世界中碳循环的运作提供新的见解，并为数值古气候和碳循环模型的配置和测试提供关键数据。这项研究将在卡迪夫大学地球与海洋科学学院进行，该学院正在积极调查地质学过去气候变化的关键间隔。我还将与其他研究所的科学家合作，特别是南安普顿国家海洋学中心和南卡罗来纳州大学（见伙伴关系详情）。