Global glaciations, also known as snowball events, represent some of Earth’s most significant climate changes. The Neoproterozoic Sturtian glaciation lasted 4–15 times longer than the subsequent Marinoan glaciation, but the causes of this dramatic difference remain unclear. The standard theory attributes the termination of such events to a pause in silicate weathering due to the absence of liquid water on continents. However, recent evidence of syn-glacial dolomite precipitation suggests the possibility of continental weathering during global glaciation. We numerically investigate water-rock reactions under limited water and fresh rock supplies to identify the key factors controlling subglacial weathering and to evaluate their impact on the carbon cycle during global glaciation. The compositions of the discharge fluid and mineral assemblage reach their steady state over a timescale determined by the rate of fresh rock supply. These steady-state compositions are identical when the ratio of the meltwater production rate () to the fresh rock supply rate () is constant (). Furthermore, the maximum estimated CO2 consumption could match Earth’s volcanic CO2 emission, assuming present-day Antarctic conditions for meltwater production and fresh rock supply. This finding contradicts the standard assumption that silicate weathering ceases during global glaciation and suggests a mechanism for the prolonged duration of the Sturtian glaciation. These results demonstrate that subglacial weathering represents a previously unrecognized feedback mechanism that could account for the dramatically different durations of Neoproterozoic snowball Earth events.
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