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arXiv 2009.09902physics.ao-phphysics.comp-phphysics.geo-ph
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气候临界级联概念模型中的盆地稳定性和极限环

Basin stability and limit cycles in a conceptual model for climate tipping cascades

Nico Wunderling, Maximilian Gelbrecht, Ricarda Winkelmann, Jürgen Kurths, Jonathan Donges

AI总结:

本研究构建了包含五个气候临界元素的概念模型,通过盆地稳定性与分岔分析发现大型冰盖对地球系统恢复力至关重要,并揭示了格陵兰冰盖与AMOC间因负反馈产生的极限环现象。

摘要:

气候系统中的临界元素是地球的大尺度子区域,在全球变暖下可能表现出阈值行为,并对人类社会产生巨大潜在影响。在此,我们研究了一个包含五个临界元素及其相互作用的子集,置于一个概念性且易于扩展的框架中:格陵兰和西南极冰盖、大西洋经向翻转环流(AMOC)、厄尔尼诺-南方涛动(ENSO)以及亚马逊雨林。在这个非线性和多稳态系统中,我们进行了盆地稳定性分析,以检测其稳定状态及相关的地球系统恢复力。利用这种方法,我们进行了包含超过35亿个集合成员的系统级全面鲁棒性分析。此外,我们使用新开发的盆地分岔分析方法,研究了部分状态失去稳定性并出现振荡的动态机制。结果表明,在全球变暖水平超过工业化前气候条件4 °C以上的情况下,四个或五个元素发生临界的状态具有最大的盆地体积。在较低的变暖水平下,包含西南极洲和格陵兰岛冰盖解体的状态比其他状态配置具有更大的盆地体积。因此,在我们的模型中,我们发现大型冰盖对地球系统恢复力具有特别重要的意义。我们还检测到在罕见的参数组合下,0.6%的集合成员出现了极限环。这种极限环振荡主要发生在格陵兰冰盖和AMOC之间(86%),这是由于它们之间的负反馈耦合。这些极限环指向了气候系统中可能存在的危险内部变率模式,它们可能在古气候动力学中发挥了作用,例如在更新世冰期周期中展开的那些过程。

英文摘要:

Tipping elements in the climate system are large-scale subregions of the Earth that might possess threshold behavior under global warming with large potential impacts on human societies. Here, we study a subset of five tipping elements and their interactions in a conceptual and easily extendable framework: the Greenland and West Antarctic Ice Sheets, the Atlantic Meridional Overturning Circulation (AMOC), the El-Nino Southern Oscillation (ENSO) and the Amazon rainforest. In this nonlinear and multistable system, we perform a basin stability analysis to detect its stable states and their associated Earth system resilience. Using this approach, we perform a system-wide and comprehensive robustness analysis with more than 3.5 billion ensemble members. Further, we investigate dynamic regimes where some of the states lose stability and oscillations appear using a newly developed basin bifurcation analysis methodology. Our results reveal that the state of four or five tipped elements has the largest basin volume for large levels of global warming beyond 4 °C above pre-industrial climate conditions. For lower levels of warming, states including disintegrated ice sheets on West Antarctica and Greenland have higher basin volume than other state configurations. Therefore in our model, we find that the large ice sheets are of particular importance for Earth system resilience. We also detect the emergence of limit cycles for 0.6% of all ensemble members at rare parameter combinations. Such limit cycle oscillations mainly occur between the Greenland Ice Sheet and AMOC (86%), due to their negative feedback coupling. These limit cycles point to possibly dangerous internal modes of variability in the climate system that could have played a role in paleoclimatic dynamics such as those unfolding during the Pleistocene ice age cycles.

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