There is now much geological evidence that the Earth was fully glaciated during several periods in the geological past (about 700Myr ago) and attained a so-called Snowball Earth (SBE) state. Additional support for this idea has come from climate models of varying complexity that show transitions to SBE states and undergo hysteresis under changes in solar radiation. In this paper, we apply large-scale bifurcation analyses to a novel, fully-implicit Earth System Model of Intermediate Complexity (I-EMIC) to study SBE transitions. The I-EMIC contains a primitive equation ocean model, a model for atmospheric heat and moisture transport, a sea ice component and formulations for the adjustment of albedo over snow and ice. With the I-EMIC, high-dimensional branches of the SBE bifurcation diagram are obtained through parameter continuation. We are able to identify stable and unstable equilibria and uncover an intricate bifurcation structure associated with the ice-albedo feedback. Moreover, large-scale linear stability analyses are performed near major bifurcations, revealing the spatial nature of destabilizing perturbations.

中文翻译：

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全隐式地球系统模型中的雪球地球分岔

现在有很多地质证据表明地球在过去的几个地质时期（大约 700Myr 前）并获得了所谓的雪球地球（SBE）状态。对这一想法的额外支持来自不同复杂性的气候模型，这些模型显示了向 SBE 状态的转变，并在太阳辐射的变化下经历了滞后。在本文中，我们将大规模分岔分析应用于一种新颖的、完全隐式的中复杂度地球系统模型 (I-EMIC) 来研究 SBE 转换。I-EMIC 包含一个原始方程海洋模型、一个大气热量和水分传输模型、一个海冰分量和用于调整冰雪反照率的公式。使用 I-EMIC，SBE 分岔图的高维分支通过参数延拓获得。我们能够识别稳定和不稳定的平衡，并揭示与冰反照率反馈相关的复杂分叉结构。