FOR 1070: Understanding Cenozoic Climate Cooling: The Role of the Hydrological Cycle, the Carbon Cycle and Vegetation Changes

FOR 1070：了解新生代气候变冷：水文循环、碳循环和植被变化的作用

• 批准号: 63178513
• 金额: --
• 依托单位: Zentrum für Marine Umweltwissenschaften (MARUM)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/63178513?language=en
• 关键词: 1070; Understanding; Cenozoic; Climate; Cooling

Since the end of the Cretaceous about 65,5 million years ago the Earth's climate has been constantly changing. While the Cretaceous was characterised by an extremely warm "greenhouse climate" with ice-free polar regions and an increased sea level, a general cooling trend that persists until today started in the subsequent Cenozoic. Evidence in deep-sea sediments indicates that this climatic development has not always been continuous. Larger cooling events took place during the transition from the Eocene to the Oligocene (about 34 million years ago) as well as during the mid-Miocene (about 14 million years ago), each time accompanied by Antarctic glaciation. The cooling events were possibly caused by global changes in ocean circulation, which might have been influenced by tectonic shifts in ocean gateways. Alternative hypotheses try to explain Cenozoic climate changes with variations of the atmospheric carbon dioxide (CO2) content, which might have decreased because of a higher continental weathering and/or the increased deposit of organic sediments in shelf seas, finally leading to Antarctic glaciation and global cooling. The Research Unit deals with the above outlined climatic development in the Cenozoic and examines the role of water and carbon cycles and vegetation as well as the role of non-CO2 greenhouse gases. First, research focusses on the mid-Miocene cooling and the subsequent expansion of grassland as well as the evolution of the modern global ocean circulation. Another subject-matter is the cooling during the transition from the Eocene to the Oligocene. Methodically, the examinations include data-based reconstructions of the palaeoenvironment as well as numerical model studies. Special emphasis is put on surveying the model results by terrestrial and marine sediment data.

自白垩纪末以来，大约6550万年前，地球的气候一直在不断变化。虽然白垩纪的特点是极端温暖的“温室气候”，极地地区无冰，海平面上升，但持续到今天的普遍冷却趋势始于随后的新生代。深海沉积物中的证据表明，这种气候发展并非总是连续的。从始新世到渐新世（约3400万年前）以及中新世中期（约1400万年前）发生了更大的冷却事件，每次都伴随着南极冰川作用。这些变冷事件可能是由于全球海洋环流的变化引起的，而全球海洋环流的变化可能受到海洋门户构造变动的影响。另一种假说试图解释新生代气候变化与大气二氧化碳（CO2）含量的变化，这可能是由于更高的大陆风化和/或增加的有机沉积物在陆架海存款，最终导致南极冰川和全球变冷。该研究股处理上述新生代气候发展，并研究水和碳循环和植被的作用以及非二氧化碳温室气体的作用。首先，研究集中在中新世中期的冷却和随后的草原扩张以及现代全球海洋环流的演变。另一个主题是从始新世到渐新世过渡期间的冷却。系统地，检查包括基于数据的古环境重建以及数值模型研究。特别强调的是，调查模式的结果，陆地和海洋沉积物数据。