Snowball earth: not quite still, PgII

Key Highlights:

• A new study analyzed sediment layers from the Cryogenian Period (720-635 million years ago) in Scotland.
• The study found evidence of short climate cycles during a phase of the "snowball earth" period.
• Researchers identified climate cycles matching solar cycles of 9-11 years (sunspot cycle) and 60-150 years (Gleissberg cycle).
• Climate simulations of snowball earth also showed a variability of two to three years, similar to El Nino.

Detailed Insights:

• The "snowball earth" theory suggests the Earth was covered in ice, even in tropical regions, during the Cryogenian Period.
• The research team analyzed 2,640 layers of sediment in the Port Askaig Formation on the Garvellach Islands in Scotland, interpreting them as annual varves.
• Thickness variations in the sediment layers revealed climate cycles corresponding to known solar cycles, indicating climate activity during the "snowball earth" period.
• The discovery suggests that even with extensive ice cover, the Earth's climate exhibited variability on timescales of years to centuries.

Scientific/Technical Concepts Involved:

• Cryogenian Period: A geological period from 720 to 635 million years ago characterized by extreme global glaciation.
• Varves: Annual layers of sediment, often found in glacial lakes, that can provide a record of past climate conditions.
• Sunspot Cycle: An approximately 11-year cycle in the Sun's activity, characterized by variations in the number of sunspots.

Geological Time-Scale