Terrestrial ecosystem and climate dynamics during the Paleocene–Eocene Thermal Maximum (~56 Ma) in the high southern latitudes: An integrated palynological/ organic geochemical study of the Margaret Point section, Southern Australia

由于人为排放，如果排放继续不减少，大气二氧化碳浓度可能在2300年左右达到1800 ppmv。地球历史上最后一次如此极端的二氧化碳浓度盛行是在古新世晚期到始新世早期（约60-50 Ma前），特别是在这个温室间隔的几次短暂的热活动期间。这些超热期的快速升温和高碳输入与当今人为碳释放及其气候后果有相似之处。其中，古新世-始新世极热期（PETM，约56 Ma）受到特别关注。其特征是大量同位素轻碳注入海洋-大气系统，代表了当前由于过量碳排放而导致的气候变化的极好古模拟。关于始新世第三纪新世对陆地生态系统的影响的资料主要来自北半球的中纬度地区。对于南半球，它仅限于来自新西兰和塔斯马尼亚岛1172海洋钻探计划站点的花粉数据。由于这些数据不仅时间分辨率有限，而且也不能完全代表南半球高纬度地区petm引起的植被变化，因此需要从这些纬度获取额外的、时间分辨率高的替代数据。因此，该项目旨在通过分析维多利亚玛格丽特点（古纬度：约60°S）露头的孢子体，重建南澳大利亚始新世热引起的陆地生态系统动态。因为博士职位的资助已经被批准，所以这里只要求学生助手，消耗品和旅行的资金。大量的试点工作表明，玛格丽特点剖面包含了始新世纪的开始，并延伸到碳同位素偏移（CIE）的主体。孢子形态数据将允许建立一个详细的，时间上高度分辨率的植被记录，从最新的古新世一直到PETM CIE。基于孢体的定量气候估计将使我们能够确定当地始新世热变暖的幅度。将孢粉学数据与合作伙伴提供的有机地球化学（MBT-CBT）温度数据进行比较，以及CIE将有助于确定碳循环扰动、植被变化和温度变化之间的相位关系。为玛格丽特点剖面生成的数据不仅将使我们对北纬高纬度地区陆地生态系统对新第三纪热诱发的气候变化的响应有前所未有的了解；它们还将有助于促进对陆地生态系统对温室气体浓度和温度大幅上升的长期反应的一般理解。

Due to anthropogenic emissions, atmospheric CO2 concentrations may reach 1800 ppmv around the year 2300 should emissions continue unabated. The last time in Earth’s history when such extreme CO2 concentrations prevailed was the late Paleocene to early Eocene (c. 60-50 Ma ago), and particularly during the several transient hyperthermals that punctuated this greenhouse interval. The rapid warming and high carbon input during these hyperthermals bear analogies to today’s anthropogenic carbon release and its climatic consequences. Among these hyperthermals, the Paleocene-Eocene Thermal Maximum (PETM; c. 56 Ma) has reached particular attention. Characterized by a massive injection of isotopically light carbon into the ocean-atmosphere system, it represents an excellent paleoanalog for present climate change as a result of excess carbon emissions.Information on the consequences of the PETM for terrestrial ecosystems is yet mainly from the mid-latitudes of the Northern Hemisphere. For the Southern Hemisphere, it is restricted to pollen data from New Zealand and Ocean Drilling Program Site 1172 off Tasmania. Because these data are not only of limited temporal resolution, but also not fully representative of PETM-induced vegetation change in the high-latitude Southern Hemisphere, there is a need for additional, temporally highly resolved proxy data from these latitudes. This project therefore aims to reconstruct PETM-induced terrestrial ecosystem dynamics in southern Australia via the analysis of sporomorphs from an outcrop at Point Margaret, Victoria (paleolatitude: c. 60 deg S). Because funding for a PhD position has already been granted otherwise, here only funds for student helpers, consumables and travel are asked for. Extensive pilote work has shown that the Point Margaret section contains the onset of the PETM and extends into the body of the carbon-isotope excursion (CIE). The sporomorph data will allow to establish a detailed, temporally highly resolved vegetation record for the latest Paleocene well into the PETM CIE. Quantitative sporomorph-based climate estimates will allow to determine the magnitude of local PETM warming. Comparison of the palynological data with organic geochemical (MBT-CBT) temperature data that will be provided by collaboration partners, and the CIE will allow to identify the phase relationships between carbon-cycle perturbation, vegetation change and temperature change. The data to be generated for the Point Margaret section will not only yield yield unprecedented insight into the response of terrestrial ecosystems in the high outhern latitudes to PETM-induced climate change; they will also help to advance the general understanding of the long-term reaction of terrestrial ecosystems to major increases in greenhouse-gas concentrations and temperature.