近日，美国加州大学伯克利分校Adrian R. Tasistro-Hart团队发现四百万年前的Marinoan雪球显示了多种冰川消融途径。该研究于2025年4月21日发表在《美国科学院院刊》杂志上。
在新元古代，地球经历了两次失控的冰反照率灾难，导致数百万年的低纬度冰川：Sturtian和Marinoan雪球。在雪球气候状态下，硅酸盐风化导致的二氧化碳消耗崩溃，大气中的二氧化碳通过火山放气积聚，直到足够强的温室导致冰川消融。冰盖的持续时间和范围对行星的宜居性至关重要，无论是在系外行星上还是在两次冰川期之间出现动物的地球上。放射性同位素年龄将Sturtian冰川期的持续时间定义为5600万年，但Marinoan冰川期（4至1500万年）的持续时间目前有1100万年的不确定性。
研究组表明纳米比亚的马里诺冰川持续了约400万年，通过冰川进退周期，垂直冰接地线运动不到10米。低纬度冰接地线的稳定性与硬雪球状态的强滞后性是一致的。持续时间的差异表明了不同的冰川消融途径，通过较长的Sturtian的较慢CO2积累和Marinoan的辐射扰动。Marinoan冰川期的短暂持续可能对动物的生存和进化至关重要，并说明了在系外行星上宜居的另一条途径。
附：英文原文
Title: Four-million-year Marinoan snowball shows multiple routes to deglaciation
Author: Tasistro-Hart, Adrian R., Macdonald, Francis A., Crowley, James L., Schmitz, Mark D.
Issue&Volume: 2025-4-21
Abstract: Twice during the Neoproterozoic Era, Earth experienced runaway ice-albedo catastrophes that resulted in multimillion year, low-latitude glaciations: the Sturtian and Marinoan snowball Earths. In the snowball climate state, CO2 consumption through silicate weathering collapses, and atmospheric CO2 accumulates via volcanic outgassing until a sufficiently strong greenhouse causes deglaciation. The duration and extent of ice cover are critical for planetary habitability, both on exoplanets and on Earth where animals emerged between the two glaciations. Radioisotopic ages have defined the duration of the Sturtian glaciation to 56 Myr, but the duration of the Marinoan glaciation (4 to 15 Myr) currently has 11 Myr of uncertainty. Here, we show that the Marinoan glaciation in Namibia lasted ca. 4 Myr with less than 10 m of vertical ice grounding line motion through glacial advance-retreat cycles. The stability of a low-latitude ice grounding line is consistent with the strong hysteresis of a hard snowball state. The disparity in durations demonstrates different routes to deglaciation, through slower CO2 accumulation for the longer Sturtian and radiative perturbation for the Marinoan. The short duration of the Marinoan glaciation may have been essential for the survival and evolution of animals and illustrates an additional path toward habitability on exoplanets.
DOI: 10.1073/pnas.2418281122
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2418281122