Snowball Earth may hide a far stranger climate cycle than anyone expected
Source: Hacker News
Credit: MTU
During the Sturtian glacial period in the Neoproterozoic Era, Earth experienced global glaciation that has been described as either “Snowball” or “Slushball” Earth scenarios. In Snowball Earth models the planet was completely ice‑covered for about 56 million years, whereas Slushball models allow thin or patchy ice and even open water in the tropics. Geological and biological evidence, however, reveal inconsistencies with both models.
A new study published in the Proceedings of the National Academy of Sciences offers an alternative explanation. Rather than a single, continuous ice cover, the model proposes cycles of glaciation and warm periods throughout the Sturtian.
Issues with “Snowball” and “Slushball” Earth models
The dramatic temperature swings that drive glaciation are linked to carbon and oxygen cycles. The later Marinoan glaciation lasted only ~4 million years—far shorter than the Sturtian. The authors note that silicate weathering, a major carbon sink, slows or stops during glaciation, allowing volcanic CO₂ to accumulate until a threshold is reached and the ice melts. This cycle operates on a ~4 million‑year timescale, matching the Marinoan but not the prolonged Sturtian glaciation.
Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2525919123
Schematic of key carbon, oxygen, and weathering processes during interglacial and Snowball states. (Credit: Proceedings of the National Academy of Sciences 2026)
Long periods of glaciation would also deplete atmospheric O₂, yet isotopic and fossil evidence shows that some life persisted throughout the Sturtian. The authors write:
“These mismatches between the predicted pCO₂ evolution and observed glacial duration, and between the predicted pO₂ evolution and observed isotopic and biological records, motivate alternative solutions to the Neoproterozoic glaciation problem.”
The Franklin Large Igneous Province and limit cycling
To reconcile geological and biological observations, the researchers employed a coupled box model to simulate Earth’s climate, carbon, and oxygen cycles. They explored a range of volcanic activity, weathering rates, and the size of the Franklin Large Igneous Province (LIP)—a massive igneous province in the Canadian Arctic that may have triggered global glaciation by drawing down CO₂ through enhanced weathering.
“Enhanced weathering by LIPs has long been acknowledged as an important climate driver across geologic time. The Franklin LIP was emplaced at ∼717 Ma, essentially coincident (within 1–2 Myr) with the onset of the Sturtian, and could have provided a sufficiently large quantity of fresh basalt to draw down CO₂ and trigger a global glaciation.”
The model shows that weathering of the Franklin LIP could have initiated repeated glaciation cycles: CO₂ builds up when weathering halts during glaciation, then is removed again as weathering resumes during interglacial hothouse phases. These “limit cycles” could sustain glaciation over the observed 56‑million‑year span while allowing oxygen—and thus life—to persist.
“If only a portion of the Franklin LIP was weathered away during the initial Snowball onset, the remaining basalt would still be available for weathering upon deglaciation, reinitiating CO₂ drawdown until another Snowball was triggered… This cycling would continue until Franklin’s weathering power (i.e., unweathered basalt) was exhausted.”
While simplified, the model offers a compelling explanation for the inconsistencies in Snowball and Slushball scenarios and may also inform our understanding of similar climate extremes on Earth‑like exoplanets.
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Snowball Earth may hide a far stranger climate cycle than anyone expected (2026, April 28). Retrieved 30 April 2026 from https://sciencex.com/news/2026-04-snowball-earth-stranger-climate.html.
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