南京大学李高军团队最新的研究揭示了大气氧化是气候变冷的潜在诱因。这一研究成果于2024年5月14日发表在《科学通报》上。

研究人员建立了一个旨在评估pO₂对气候影响的数值模型，该模型考虑了pO₂对风化层厚度的影响及其对花岗岩区域风化持续时间的影响。模型模拟显示，通过花岗岩风化层中更深的氧化风化前沿的渗透，风化效率的增加将独立地引入高达约8°C的稳态气候冷却，与pO₂的一个数量级上升同步。

这种温度变化可能反复引发失控的冰反照率反馈，导致全球冰川事件(如新元古代雪球地球)。显生宙期间，pO₂的大量增加导致花岗岩风化效率增加，这可能也是冰室气候发展的原因之一。

据悉，大气CO₂的长期变化和随之而来的全球气候变化通常被归因于全球除气作用和硅酸盐风化的效率，这可能与地质时期的山脉形成、陆地/岛弧分布和植物定殖有关。虽然氧化风化作用通过含铁矿物的氧化作用在风化前沿的传播中发挥了重要作用，但大气O₂浓度(pO₂)对硅酸盐风化、CO₂消耗和全球气候的影响尚未得到全面评估。

附：英文原文

Title: Atmospheric oxygenation as a potential trigger for climate cooling

Author: Gaojun Li

Issue&Volume: 2024/05/14

Abstract: Secular changes in atmospheric CO₂ and consequent global climate variations, are commonly attributed to global outgassing and the efficiency of silicate weathering, which may have been linked to mountain formation, land/arc distribution, and plant colonization through geological time. Although oxidative weathering has been shown to exert a significant role in the propagation of weathering fronts through the oxidation of Fe-bearing minerals, the influence of atmospheric O₂ concentration (pO₂) on silicate weathering, CO₂ consumption and global climate has not been thoroughly evaluated. This study presents a numerical model aimed at estimating the effects of pO₂ on the climate, considering the influence of pO₂ on the regolith thickness and thus weathering duration of granitic domains. Our model simulations reveal that an increase in weathering efficiency, through deeper penetration of the oxidative weathering front in the granitic regolith, would independently introduce a steady-state climate cooling of up to ～8 °C, in step with one-order of magnitude rise in pO₂. This temperature change may have repeatedly initiated the runaway ice-albedo feedback, leading to global glacial events (e.g., Neoproterozoic Snowball Earth). Increasing granitic weathering efficiency caused by a substantial pO₂ increase may also have contributed to the development of icehouse climate during the Phanerozoic.

DOI: 10.1016/j.scib.2024.05.006

Source: https://www.sciencedirect.com/science/article/abs/pii/S2095927324003402