Exploring the Limits of Life on Earth: Environmental Extremes of the Neoproterozoic 'Super' Glacial and Interglacial Cycles

探索地球上生命的极限：新元古代“超级”冰川和间冰期循环的极端环境

• 批准号: 9907640
• 负责人: Nicholas Christie-Blick
• 金额: $ 21.72万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-10-01 至 2001-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9907640&HistoricalAwards=false
• 关键词: Exploring; Limits; Life; Earth; Environmental

AbstractThe geoloica1 record of the Neoproterozoic Era (1,000-543 Ma) indicates that Earth's climate alternated between warm equable conditions anti severe glacial conditions in which continental-scale ice sheets extended at sea level equatorward of 20 latitude. Macroscopic multicellular organisms make their first unequivocal appearance in the fossil record just prior to the Varanger glacial interval (600-575 Ma). Researchers have speculated that the extreme climatic conditions of tile Varanger glaciation may have acted as a catalyst for the rapid evolution of more complex metaoans such as the Ediacara fauna in the latest Neoproterozoic. For this to be so, however, the ancestral metazoans first had to endure what was quite probably the harshest global climate to have existed since the beginning of Earth history. and then had to survive an equally harsh phase of rapid global warming. This project seeks to better quantify the range of paleoclimatic conditions through which the early metazoans survived from the height of the Varanger glaciation to the warm, post-glacial conditions. What combination of climate forcingfactors and feedbacks can best reproduce the extreme glacial conditions, and yet provide a means of returning to a warmer, more equable climate? What were Earth surface conditions like in terms of temperature and aridity?The project will employ existing geological data to create improved reconstructions of Neoproterozoic paleogeography. Thc reconstruction will then be used as boundary conditions for a series of climate model simulations using a state-of- thc-art global climate model (GCM). Building upon our body of previous simulations, which used an older, coarse-resolution GCM. we have designed a sequence of experiments that will examine the Neoprotenozoic extreme cold phases, extreme warm phases, and transitional phases from one state to the other. The new simulations add realism and accuracy that will allow for a better description of regional climate conditions and help us delimit the range of forcings and feedback processes that operated during this pivotal period in Earth history. Rigorous and quantitative examination of the results will provide detailed new information about how such a severe climatic deterioration could have occurred here on Earth, and how the climate system recovered to more equable state. This project should yield valuable insights into the long-term ability of Earth life forms to adapt to extreme environmental conditions, and will expand our view of other planetary environments that may have supported, or be capable of supporting, Earth-like life.

新元古代（1000 - 543Ma）的地质记录表明，地球气候在温暖的稳定状态和严重的冰川状态之间交替变化，在这种情况下，大陆规模的冰盖在海平面上向赤道方向延伸20度。宏观的多细胞生物在化石记录中首次明确出现在瓦兰格冰期（600 - 575 Ma）之前。研究人员推测，瓦兰格冰川作用的极端气候条件可能是新元古代晚期更复杂的变形动物（如埃迪卡拉动物群）快速进化的催化剂。然而，要做到这一点，后生动物祖先首先必须忍受自地球历史开始以来最严酷的全球气候。然后又经历了同样严酷的全球变暖阶段 该项目旨在更好地量化古气候条件的范围，通过这些条件，早期后生动物从瓦兰格冰川的高度到温暖的冰后期条件得以生存。什么样的气候强迫因素和反馈的组合可以最好地再现极端的冰川条件，同时又提供了一种回到更温暖，更稳定的气候的方法？地球表面的温度和干燥度是什么样的？该项目将利用现有的地质数据来创建改进的新元古代古地理重建。然后，重建将被用作边界条件的一系列气候模式模拟使用一个国家的最先进的全球气候模式（GCM）。建立在我们以前的模拟基础上，使用较旧的粗分辨率GCM。我们设计了一系列的实验来研究新元古代的极冷阶段、极暖阶段和从一种状态到另一种状态的过渡阶段。 新的模拟增加了真实性和准确性，这将使我们能够更好地描述区域气候条件，并帮助我们划定在地球历史上这一关键时期运作的强迫和反馈过程的范围。对结果进行严格和定量的检查将提供详细的新信息，说明地球上如何发生如此严重的气候恶化，以及气候系统如何恢复到更稳定的状态。该项目将对地球生命形式适应极端环境条件的长期能力产生有价值的见解，并将扩大我们对可能支持或能够支持类地生命的其他行星环境的看法。