I'm talking about establishing a self-sufficient colony somewhere other than Earth. We have a major crisis on our hands. And few are even willing to consider let alone research and confirm that we're talking about an extinction event much sooner than we thought, maybe on the order of just a couple years out. Problem is, we don't know. Bigger problem is, we're not doing anything about it.

If its affordable to send people to an off world colony then its affordable to bomb it when war on Earth breaks out. Fleeing isn't going to help in a wartime situation and the idea it will not be targeted by world powers is a little naive.

I said nothing about war..?

There's no other conceivable extinction event that could occur "a couple years out". If you're talking climate change, then I agree that's a major problem, but on the order of at least decades.

Plus climate change would have to get pretty incredibly bad for, say, Mars to start looking easier to live on than Earth.

That's the problem with colonization as an Earth back-up—even Antarctica and the Sahara Desert are more livable than any other body in the Solar System, by a long shot. Another Snowball Earth or a heavily desertified Earth would still be preferable to Mars. Throw in a fair amount of radiation, even—still better.

Cuts down significantly on the sorts of events for which a Martian back-up world is preferable to a shelter-in-place strategy.

But if you could go out now and terraform a planet so that when in future you have problems here you have a place to go to that matches the original environment back on earth. And you learn a lot of things about "geo"engineering, the things you cannot try safely at home, which can come in handy to fix any problem back on earth.

We have no ability to terraform anything, let alone a planet, let alone the economics of it ever being feasible. Life isn't a star trek episode. We can't just go and 'terraform now' as you say. We can barely land anything on Mars without a 50% failrate right now. We're talking technology way, way into the future. Hundreds, perhaps thousands, of years.

This is precisely what we don't know. If you're talking averages, then sure it takes decades to observe a meaningful change. However climate change of the sort we're anticipating now isn't about averages. It's about peaks, it's about records, and possibly major shifts in equilibrium.

Basically what we witness so far and will keep on seeing are spikes in all directions of the spectrums (e.g. record high temps, but also record lows; rain in the Death Valley and droughts in formerly wet areas). More critically, what little we've been able to gather on how fast climate eras shift from one to the next, it appears that whereas in-cycle change happens rather slowly (change within an era, because averages), climate era shifts could happen very quickly (because chain of events). We're talking going from a warm era to a glacial one within a few years, sometimes months even. A high speculation is that some thongs might upset the Gulfstream and you'd observe climate evolve from year to year.

What about a comet impact? That's extinction level and comes with very little warning.

Given our limited sky coverage, we can't really rule out killer meteor on the time scale of "a couple of years", or even a couple of hours, though the probability is extremely low (like, sub-1-in-100 million, for the couple of years time frame.)

Still probably higher than extinction from war in the same time frame.

> There's no other conceivable extinction event that could occur "a couple years out".

Life on earth could end in the next five minutes. :) https://www.youtube.com/watch?v=RLykC1VN7NY

The resources and practically to gently shoving a comet or asteroid out of the way are probably a billion less than building self-sustaining colonies elsewhere. Worse, now we have two planets to defend, not one.

I don't see the "we must migrate now" types saying "lets put migration away for a while so we can better build anti-asteroid solutions and detection systems."

Arguably, we're just a couple launches and deployments of mass drivers away from fixing this issue. This is all known tech that could be deployed relatively quickly. A self-sustaining Martian colony is probably hundreds of years away considering the work it would take to terraform the planet.

The resources involved in preventing a GRB from hitting us, on the other hand, are . . .

. . . actually I have absolutely no idea how you would practically do that at all.

He appeared to be speaking of a known, ongoing crisis, not a minute possibility of a killer meteor.

Haha! My link doesn't go to a video about meteors. Your point is taken, though. I was just being cute and/or hoping you hadn't heard about this.

But I have heard the possibility of a GRB discussed seriously as a motivator for expanding, not just through the solar system, but through the galaxy.

Lots of good reasons to establish a space colony, fleeing the earth is not one of them. By this sort of argument you actually discredit the idea of space exploration.

> fleeing the earth is not one of them

Why not? If a big asteroid is going to hit earth (for example), fleeing is a pretty reasonable response. It's also a reasonable defense against technobiological hazards.

The impact would have to be absolutely massive to cause enough damage to the Earth that it is less liveable than Mars.

To compare, the Triassic–Jurassic extinction event created an Earth still more liveable than Mars. Even if we go way back in time, to when there was no land-life on Earth and a poorly oxygenated atmosphere, the Earth is still better off than Mars for supporting human life.

If the goal is to save the human race, then it'd be better to have a few high orbit or lunar habitats, then if something wipes out the majority of civilisation on Earth, we immediately begin recolonisation of our home planet.

Let me ask you this question: Would you consider the Titanic, oh, I don't know -- a success story?

Because that's basically what this sort of thing comes down to, at the end of it. There's basically nothing that is going to be existentially, immediately threatening to earth on a timescale that Mars is actually a more livable environment.

Where else in the Solar System could we even get the amount of water we would need?

Isn't Mars full of water? Source: I read the Mars trilogy by Kim Stanley Robinson.

The chance that an asteroid hitting Earth that actually matters is extremely low. It is even lower chance that we can detect it on time. It is much higher chance that politicians will start a nuclear war that wipes out most of humanity from the face of Earth.

I'm not certain what you mean by "fleeing", but we sure as hell aren't going to move seven billion people. A bunch of engineers and rich people may be able to get out, but that's about it. To save the rest, we'll need cheaper methods.