[neckardt]

If I'm understanding you correctly, your argument is that if we don't become a multi-planetary species, extinction is assured. And we don't stand a chance of going multi-planetary if we don't take advantage of cheap fossil fuels within the next several years.

Why do think we need to leverage fossil fuels to build rockets? My impression was that solar and wind are already out-competing coal in terms of electricity production, and are close to beating natural gas too.

I also don't think fossil fuels are required to build rockets. Hydrogen can easily be generated from electrolysis (although a bit more expensive than from methane), Methane can be produced from plants, and while I haven't heard it tried yet I imagine a fuel similar to RP-1 could also be synthesized from plants, similar to how we make ethanol.

Do you think we won't be able to switch to renewables in time, or is my analysis on how effective renewables are off?

[gbear605]

My reading of the comment you were responding to is that they were saying "We needed to leverage fossil fuels to get to the state of development where we can build rockets, and if we didn't have that fuel in the ground, we'd be stuck pre-industrial. Future societies won't have that fuel, so we're the only chance (for millions of years) of becoming multiplanetary"

[gxon]

Exactly this. Before the oil age, we were already rapidly decimating forests for fuel. In a way, the discover of fossil fuels averted that ecological disaster and there are more trees now (in America at least) than 100 years ago [1].

Solar and wind energy generation are great, but don't have a high ERoEI in early development. Oil that's gushing out of the ground has an insanely high ERoEI and we used that to advance our technology very quickly.

Also remember that we probably have only a few hundred million years left before the sun expands and heats the planet to the point were complex life can't exist. There will be no liquid water in 1 billion years.

This is all conjecture. It certainly could be possible that future civilizations can become space faring by a different path than we took, but that's a terrible gamble to make if you think intelligence in the universe is worth preserving and expanding.

1. https://www.treehugger.com/more-trees-than-there-were-years-...

[neckardt]

Ah so if your civilization ends but humans ad a spicies survive, the next civilization won't have it so easy. That makes sense, thanks for clarifying.