About 700m years ago, the Earth froze over entirely - now we may know why

[muriel_volestrangler]

It’s hard to believe, but about 700m years ago it’s thought that our planet completely froze over with little to no liquid ocean or lakes exposed to the atmosphere, even in the tropics. But what tipped Earth’s climate into “Snowball Earth” state? A new study suggests a cold climate and massive volcanic eruptions set the scene.

The Franklin eruptions – about 720m years ago – spewed out vast amounts of fresh rock, stretching from what is now Alaska, through northern Canada to Greenland. Similarly large eruptions have happened at other times, but this one happened to coincide with an already cold climate. And combined with a lack of plants (they hadn’t evolved yet) these eruptions exposed a huge carpet of fresh rock to intense weathering.

Chemical reactions associated with weathering remove carbon dioxide from the air. By modelling the climate impact, researchers have shown that rapid erosion over such a large area could have pulled down enough carbon dioxide to tip Earth into a snowball state. The findings, which are published in the Journal of Geophysical Research: Planets, also show that similar-sized volcanic eruptions at other times in Earth’s history failed to generate snowball conditions because they occurred when the background climate was hotter, or at times when vegetation cover slowed the rate of erosion.

https://www.theguardian.com/science/2025/jul/23/about-700m-years-ago-the-earth-froze-over-entirely-now-we-may-know-why

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008701?af=R (copying disabled, so I can't post their abstract or plain language summary here, but the full paper is there)

[IbogaProject]

1. Here just clicking through w journal worked

Plain Language Summary
During the Neoproterozoic eon (c. 1,000−1,540 Ma), the Earth plunged into the Snowball climate state, but the causes for this event are still debated. One hypothesis is that increased weathering of silicate rocks, which draws co2 out of the atmosphere, caused global cooling by reducing the greenhouse effect. Recently, precise dating of Neoproterozoic geologic events showed that a massive expanse of particularly weatherable minerals erupted directly before the Sturtian Snowball event, suggesting that it enhanced silicate weathering enough to cause the Snowball. We model the weathering process and climate response and show that this is indeed a feasible Snowball trigger mechanism given a cold background climate, rapid weathering and erosion over a large area, and persistent weathering even as the climate cools. Proposed causes for Snowball events must also explain why other Snowball events did not occur earlier or later in Earth's history; we show that earlier in Earth's history, higher levels of atmospheric co2 may have made the climate more stable against sudden changes in weathering, and later in Earth's history, Snowball events may have been prevented by hot background temperatures or less efficient weathering

[muriel_volestrangler]

2. Thanks - odd how the link is working

I copied the Guardian's version, which is /doi/epdf/ , and that gives me the full paper, but a banner saying "you are viewing this document with limited shared access. Some features may be limited or disabled", and, sure enough, it has copying disabled. But when I follow that same link from my DU post, as you did, it gets changed to "/doi/abs/", and the copyable abstract is shown.

[Xoan]

3. The causes of Snowball Earth events,

rare global glaciations important for the evolution of life, are unknown. Recent geochronology of the Sturtian Snowball and Franklin Large Igneous Province (LIP) suggest that the Franklin caused the Sturtian via
drawdown by silicate weathering. By modeling the climate response to LIP weathering, we show that this initiation mechanism is feasible given a cold background climate, rapid chemical weathering and erosion over a large area, and a weak sensitivity of the silicate weathering feedback strength. Our model indicates that similar Phanerozoic LIPs may have failed to trigger Snowballs due to hot background climates and lower erosion rates caused by lower topography or vegetation, while high
suppressed LIP perturbations earlier in Earth history. We therefore argue that Snowball initiation by weathering of the Franklin is plausible and consistent with the lack of Snowballs in the Phanerozoic and mid

[IbogaProject]

4. Sun was cooler then

And another scary part is these "sudden" historic tempreature shifts excepting the big pemerin extinction were of much longer time intervals than than current one.