Snowball Earth may hide a far stranger climate cycle than anyone expected
3 hours ago
- #Climate Cycles
- #Snowball Earth
- #Neoproterozoic Era
- Snowball Earth models suggest complete ice cover for 56 million years, while Slushball models allow some open water, but both face inconsistencies with geological and biological evidence.
- A new study proposes cycles of glaciation and warm periods during the Sturtian period, instead of continuous ice, to explain mismatches in carbon and oxygen cycles.
- The time scale for glaciation cycles linked to silicate weathering is around 4 million years, fitting the shorter Marinoan period but not the longer Sturtian, which lasted 56 million years.
- Prolonged glaciation should deplete oxygen, yet life persisted during the Sturtian, motivating alternative explanations for Neoproterozoic glaciation.
- Researchers used a coupled box model, incorporating volcanic activity, weathering rates, and the Franklin Large Igneous Province (LIP), which may have triggered glaciation by drawing down CO2 through enhanced weathering.
- The model shows the Franklin LIP triggered repeated glaciation cycles: CO2 builds up when weathering halts during glaciation, then depletes upon deglaciation, allowing multiple glaciations over 56 million years and explaining oxygen persistence for life.
- This 'limit cycling' between extreme climates continued until the Franklin LIP's weathering power was exhausted, offering a compelling alternative to Snowball/Slushball models and insights for exoplanet studies.