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Can the Jormungand hypothesis be an alternative explanation for the Neoproterozoic pan-glaciations?

耶蒙加德假说能否成为新元古代泛冰川作用的另一种解释？

基本信息

批准号：
392282600
负责人：
Professor Dr. Joaquim G. Pinto, since 1/2021
金额：
--
依托单位：
Institut für Meteorologie und Geophysik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2018
资助国家：
德国
起止时间：
2017-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/392282600?language=en
关键词：
Jormungand hypothesis alternative explanation Neoproterozoic

项目摘要

The pan-glaciations of the Neoproterozoic era (1000-541 Million years before present) are among the most extreme and most exciting climates in the history of Earth. The Neoproterozoic geology provides ample evidence for two million-year long glaciations during which tropical continents were covered by widespread glaciers that reached down to sea level. The classical Snowball Earth theory posits that this can only be explained if one assumes that the oceans were completely covered by sea ice. In 2011, however, the PI together with colleagues from the University of Chicago proposed the alternative Jormungand hypothesis. As the Snowball Earth theory the Jormungand hypothesis can explain the Neoproterozoic geology and offers a scenario for an entire lifecycle of the pan-glaciations. In contrast to the Snowball Earth theory, however, the Jormungand hypothesis allows for a small strip of open equatorial ocean, because of which it can much more easily explain how life survived these extreme climates. The Jormungand hypothesis, and the hysteresis associated with it are created by fundamental dynamics of the atmosphere and the impact of the Hadley circulation on the subtropical hydrological cycle and sea-ice albedo. The Jormungand hypothesis has been successfully demonstrated in energy balance models as well as global climate model simulations in aquaplanet setup without ocean and sea-ice dynamics. Yet, in order to assess whether the Jormungand hypothesis can in fact be a viable alternative to the Snowball Earth theory, climate model simulations in realistic model setups are needed. The project therefore aims to study the Jormungand hypothesis through simulations with the global climate model ICON. The simulations will take a hierarchical approach to investigate the impact of continents, subtropical wind-driven ocean cells, and ocean and sea-ice dynamics in general. Four questions will be addressed: 1) Is the Jormungand hypothesis a robust model feature of idealized aquaplanet setups? 2.) How do continents and their geometry affect the Jormungand hypothesis? 3.) How does ocean energy transport affect the Jormungand hypothesis, and does this depend on continents? 4.) Can we demonstrate the Jormungand hypothesis in a coupled atmosphere-ocean model with realistic Neoproterozoic continents, ocean dynamics, and sea-ice dynamics, and if so what determines the magnitude of Jormungand hysteresis? The Neoproterozoic pan-glaciations are among the most exciting topics in fundamental climate dynamics. In addition, the project promises to test the new climate model ICON in a state very different from today, and to lead to insights that could be relevant also to the habitability of extrasolar planets.

新元古代（距今1000- 5.41亿年）的泛冰川作用是地球历史上最极端和最令人兴奋的气候之一。新元古代的地质学提供了充足的证据，证明了长达200万年的冰川作用，在此期间，热带大陆被大面积的冰川覆盖，冰川一直延伸到海平面。经典的雪球地球理论认为，只有假设海洋完全被海冰覆盖，才能解释这一点。然而，在2011年，PI与芝加哥大学的同事一起提出了Jormungand假说。Jormungand假说与雪球地球理论一样，可以解释新元古代地质，并为泛冰川的整个生命周期提供了一个场景。然而，与雪球地球理论相反，Jormungand假设允许一小条开放的赤道海洋，因为它可以更容易地解释生命如何在这些极端气候中生存下来。Jormungand假说以及与之相关的滞后现象是由大气的基本动力学和Hadley环流对亚热带水文循环和海冰环流的影响造成的。Jormungand假说已成功地证明了在能量平衡模式，以及全球气候模式模拟在aquaplanet设置没有海洋和海冰动力学。然而，为了评估Jormungand假设是否真的可以成为雪球地球理论的可行替代方案，需要在现实的模型设置中进行气候模型模拟。因此，该项目旨在通过全球气候模型ICON的模拟来研究Jormungand假设。模拟将采取分层的方法来研究大陆，亚热带风驱动的海洋细胞，以及海洋和海冰动力学的影响。四个问题将被解决：1）Jormungand假设是一个强大的模型功能的理想化水行星设置？2.）的情况。大陆及其几何形状如何影响Jormungand假说？3.）第三章海洋能量传输如何影响Jormungand假说，这是否取决于大陆？4.）我们能否在一个具有现实的新元古代大陆、海洋动力学和海冰动力学的大气-海洋耦合模型中证明Jormungand假说？如果可以，是什么决定了Jormungand滞后的大小？新元古代泛冰川作用是基础气候动力学中最令人兴奋的课题之一。此外，该项目承诺在与今天截然不同的状态下测试新的气候模型ICON，并得出可能与太阳系外行星的可居住性相关的见解。