See also:<p><a href="https://news.ycombinator.com/item?id=39315378">https://news.ycombinator.com/item?id=39315378</a> (<i>An extreme ice-age climate 700M years ago</i>)<p><i>What Turned Earth Into A Giant Snowball 700 Million Years Ago?</i> (astrobiology.com)<p>4 days ago (81+ points / 89+ comments)
A recent PBS documentary did a great job talking about all the changes the earth has gone through:<p><a href="https://www.pbs.org/wgbh/nova/article/the-history-of-earth-in-five-epic-chapters/" rel="nofollow">https://www.pbs.org/wgbh/nova/article/the-history-of-earth-i...</a><p>They had a series on planets and some of their history too.<p>Growing up I honestly thought that planets evolved into a sort of natural stable state that I guess I assumed would last until the sun or other external force decided otherwise. But it’s interesting how throughout time the earth has dramatically changed due to “minor” changes like volcanic activity changes, the introduction of, water, oxygen, or bacteria or other chemicals.<p>I had thought the sun and distance from it really was the determining factor as far as the temperature generally goes.
Seems like a low risk approach for taking over a planet would be to just park a large shade between the planet and it's star then let it enter a deep freeze. Then you could just remove the shade and let the planet warm back up before settling down.
> Co-author Professor Dietmar Müller from the University of Sydney said: Geology ruled climate at this time. We think the Sturtian ice age kicked in due to a double whammy: a plate tectonic reorganisation brought volcanic degassing to a minimum, while simultaneously a continental volcanic province in Canada started eroding away, consuming atmospheric CO2.<p>Research:<p>> Duration of Sturtian “Snowball Earth” glaciation linked to exceptionally low mid-ocean ridge outgassing’, Dutkiewicz, A. et al (Geology, 2024). DOI: 10.1130/G51669.1
I remember it was one of the remarkable take-away points of nonlinear system dynamics, aka chaos theory: the weather/climate system doesn't even have an "average regime" that it converges on. You can average over longer periods of time, and the resulting sequence doesn't necessarily converge to a single limit. Pretty mind boggling when you think about it. Long term enough, "this place's climate" doesn't even exist.
Not mentioned but still important, the Sun’s output very slowly rises over time and so was significantly lower 600 million years. We are in a ~2 billion year wide sweet spot where multicellular life can thrive in a high oxygen low CO2 atmosphere.
The more that we learn about the evolution of Earth as a planet, the more I think that the development of complex life is an exceedingly low probability event. So many things had to go “just right” for conditions on Earth to allow the formation of life.<p>It’s mind blowing to me that one of those things is the collision of a proto Earth that created the Moon which was just the right size to stabilize the Earth’s rotation.<p>On top of that, life on Earth required, vulcanism, plate tectonics, carbon cycle, magnetic field, collection of water, location and size of Jupiter and clearing of asteroids, near extinction events that were survivable by some life, etc….
The paper: <a href="https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51669.1/633748/Duration-of-Sturtian-Snowball-Earth-glaciation" rel="nofollow">https://pubs.geoscienceworld.org/gsa/geology/article/doi/10....</a>
There is a fantastic BBC Horizons documentary from the 90s called Snowball Earth that was easy to find on YouTube the last time I looked, but just now I see a hot mess of search results and if it's still in there somewhere I can't find it.<p>EDIT: found it on dailymotion and its a great story of how the radical theory was rejected then accepted.
<a href="https://www.dailymotion.com/video/x7o0b66" rel="nofollow">https://www.dailymotion.com/video/x7o0b66</a>
So, Ice Ball or Venus.<p>Seems like climate is more sensitive than we think.<p>Man made impact or not, the whole system seems on a knifes edge of tipping towards the extremes. That we are living right now is rare in-between point.
Coincidentally, I was just watching Myron Cook's video on the Great Unconformity (<a href="https://en.wikipedia.org/wiki/Great_Unconformity" rel="nofollow">https://en.wikipedia.org/wiki/Great_Unconformity</a>, although that page only briefly discusses the "Snowball Earth" connection).<p><a href="https://www.youtube.com/watch?v=LXzDfQyUlLg" rel="nofollow">https://www.youtube.com/watch?v=LXzDfQyUlLg</a><p>Beautiful scenery and an excellent discussion of geological strata.
From the article: "The team's work raises intriguing questions about Earth's long-term future. A recent theory proposed that over the next 250 million years, Earth would evolve towards Pangea Ultima, a supercontinent so hot that mammals might become extinct."<p>I'll keep this handy as a smart quip next time someone tries to convince me that human-led climate warming is a thing.