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.
What made Earth a giant snowball 700M years ago? Scientists have an answer
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Re: What made Earth a giant snowball 700M years ago? Scientists have an answer
#32Re: What made Earth a giant snowball 700M years ago? Scientists have an answer
#33Earlier quoted context omitted.
That'd make for a good story setup: aliens park a shadeship (c) at L1 and wait. They block out most but not all of the sun. After some time (months? years?), conditions on Earth become unbearable, so earthlings have to mount an attack. Kind of like the movie Sunshine, but with more believable physics. Edit: as a bonus, it could take place in ~50-100 years, when global warming has gotten worse. The aliens could disgui…
Love this idea for a story. As an alternative - it could be the oil producing countries, not aliens - seeking shade earth to disrupt solar and wind energy, and return to oil dominance.
Well, if Exxon builds a space ship…
Re: What made Earth a giant snowball 700M years ago? Scientists have an answer
#34Earlier quoted context omitted.
Have you done the calculation how much material is required for such an endeavor? I bet there are more cost effective approaches.
> Have you done the calculation how much material is required for such an endeavor? It's a tiny fraction of what's required for a proper Dyson sphere. And we know civilizations can afford those because we can no longer see their stars. For anyone who's hung up on saving nickle, we could do a low budget Worldring² or even thriftier Shadow Squares®. ²Nivenlarry ®Larry Niven
> And we know civilizations can afford those because we can no longer see their stars.
That's a giant claim you just made like it's fact.
Re: What made Earth a giant snowball 700M years ago? Scientists have an answer
#35Seems 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.
Or you could just smack it with a really big rock. That nicely sterlizes the planet too, so you can reseed it with life from your planet after to make it more comfortable. Honestly it's all kind of silly because distances are so vast. It makes little sense to travel to a distant star - much better to build space habitats in your own star system. And even if you were going to do that for some crazy reason, there's no…
I was thinking the deep freeze might be useful in preserving some potential food sources, assuming it happens quickly enough. But I agree sterilizing the planet provides some advantage as well.
Re: What made Earth a giant snowball 700M years ago? Scientists have an answer
#36So, Ice Ball or Venus. Seems like climate is more sensitive than we think. 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.
It could be the stability of Earth's systems is just an illusion created by observer selection. If it had not been within limits, we wouldn't be here. This places no constraint on how stable it will be in the future. Another part of the system that could be like that is the oxygen content of the atmosphere. The time constant for variation in O2 level is just a few million years (due to consumption of O2 by release of…
Stability is an illusion. It’s becoming increasingly evident that even small shifts in climate have triggered devastating events for humans, like the Bronze Age Collapse, plagues, and so on. Plus, there’s the whole end of the last glaciation that likely created the various flood myths and wiped out most of the megafauna.
Re: What made Earth a giant snowball 700M years ago? Scientists have an answer
#37Earlier quoted context omitted.
If they had made the death star bigger, they could have done this tbh.
Wouldn't moving the death star closer to the sun sort that out ?
Closer to the star would only help if the star's size was similar to the death star. And if the death star was made larger then it wouldn't be mistaken for a small moon.
Re: What made Earth a giant snowball 700M years ago? Scientists have an answer
#38Earlier quoted context omitted.
Have you done the calculation how much material is required for such an endeavor? I bet there are more cost effective approaches.
> Have you done the calculation how much material is required for such an endeavor? It's a tiny fraction of what's required for a proper Dyson sphere. And we know civilizations can afford those because we can no longer see their stars. For anyone who's hung up on saving nickle, we could do a low budget Worldring² or even thriftier Shadow Squares®. ²Nivenlarry ®Larry Niven
I really liked Pandora's Star (The Commonwealth Saga) by Peter F. Hamilton.
Re: What made Earth a giant snowball 700M years ago? Scientists have an answer
#39> 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.
Research:
> 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
Re: What made Earth a giant snowball 700M years ago? Scientists have an answer
#40So, Ice Ball or Venus. Seems like climate is more sensitive than we think. 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.
The process they described took millions of years. Yeah, we're probably in a somewhat rare in-between point. That "point" is still unimaginably long.
Sediment cores show extreme temperature oscillations over far shorter time frames. This [1] is 5 million years of temperature reconstructions based on the Vostok ice cores. Keep in mind the scale, the difference between the peaks and valleys is 10 degrees celsius!
But the really interesting thing is that that derived from this [2], which is Earth's temperature over the past 65 million years. Those previous extremes just blur, because now you're talking about a temperature difference of 20 degrees celcius, no ice on the planet, and giant beasts roaming in lush greenery. Greenery which was basically everywhere, even Antarctica! [3]
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[1] - https://en.wikipedia.org/wiki/Geologic_temperature_record#/m...
[2] - https://en.wikipedia.org/wiki/Geologic_temperature_record#/m...
[3] - https://en.wikipedia.org/wiki/Eocene#/media/File:Ypresian_Ea...
