Carrillo Judit, Mann Michael E, Marinov Irina, Christiansen Shannon A, Willeit Matteo, Ganopolski Andrey
Department of Earth and Environmental Science, University of Pennsylvania, Pennsylvania, PA 19104.
Department of Applied Physics, University of La Laguna, La Laguna 38200, Spain.
Proc Natl Acad Sci U S A. 2025 Jun 10;122(23):e2427236122. doi: 10.1073/pnas.2427236122. Epub 2025 Jun 2.
The Earth system model CLIMBER-2 has been used in past work to successfully reproduce the glacial/interglacial cycles of the Plio-Pleistocene and the Mid-Pleistocene Transition (MPT) from predominantly 40 to 100 ky timescale oscillatory behavior as a function of declining volcanic outgassing and regolith removal. In this study, we further examine the sensitivity of this previous work to varying prescribed levels of volcanic outgassing and regolith extent and the long-term dynamics of the global carbon cycle, affecting the exchange and partitioning of carbon between different Earth system reservoirs and therefore global atmospheric CO concentrations. As volcanic outgassing decreases, CO and land carbon storage decrease, while ocean carbon storage, including CaCO sediment, increases. At volcanic outgassing levels below a threshold value of roughly 5.7 Tmol C yr, sea level decreases due to land ice formation, leading to increased carbon accumulation in the ocean and decreased carbon in the CaCO sediment reservoir. Our previous finding of strong hysteresis and path dependence in the glacial/interglacial alternation history [J. Carrillo , 121, e2322926121 (2024)] appears to be a tenuous climate feature, dependent on the precise representation of carbon cycle processes and, specifically, the numerical precision used in the calculation of certain key state variables in the model's carbon cycle.
地球系统模型CLIMBER-2在过去的研究中被用于成功再现上新世-更新世的冰期/间冰期循环以及中更新世过渡（MPT），其主要表现为40至100ky时间尺度上的振荡行为，这是火山排气量下降和风化层剥蚀的函数。在本研究中，我们进一步研究了先前工作对不同规定火山排气量水平和风化层范围变化的敏感性，以及全球碳循环的长期动态，这会影响不同地球系统储库之间碳的交换和分配，进而影响全球大气CO浓度。随着火山排气量减少，CO和陆地碳储量减少，而包括CaCO沉积物在内的海洋碳储量增加。当火山排气量低于约5.7 Tmol C yr的阈值时，由于陆地冰的形成海平面下降，导致海洋中碳积累增加，CaCO沉积物储库中的碳减少。我们先前在冰期/间冰期交替历史中发现的强烈滞后和路径依赖性[J. Carrillo, 121, e2322926121 (2024)]似乎是一个脆弱的气候特征，取决于碳循环过程的精确表示，特别是模型碳循环中某些关键状态变量计算中使用的数值精度。
