Are you personally currently environmentally apathetic because you know China is shoving as much burned coal into the air as they can?
Are you personally currently environmentally apathetic because you know somewhere there are some unspoiled mountain lakes that are still hardly touched by the hand of man?
Are you personally unconcerned about the possibility of your home being nuked because thank goodness Alaska will probably survive?
You hypothesize a very bizarrely precise self-interest that very suddenly gives way to complete wild suicidal abandon at a very precise point. I'm not at all convinced what you've ordered up here can exist.
There is a pretty clear body of evidence that humans do not expend resources on something they don't value. And the question of whether or not the value of the planet would change with the expansion into space is a reasonable one to ask.
I believe what is posited is not precise self-interest so much as a reevaluation of risk and its concomitant change to the cost of failure.
As an example, one might speed down the highway with a perception of low risk of being caught, but that behavior might change if a sign appeared that said "speed limit enforcers are on duty." So in the presence of the new information a re-evaluation of the risk of being cited is undertaken and behavior may (or may not) change.
The question posed is whether or not the value calculus that currently drives the environmental and military engagement thinking of the world today, would be altered by the existence of a stable 'somewhere else'. That is a general question and not one that turns on precise self interest.
I do not believe such a settlement would change the value equation, as it would not apply to a large enough fraction of the current residents to change the calculus. Now I also would not expect the prototypical someone who was born and raised on Mars to feel particularly motivated to change what folks on Earth were doing, just as non-Chinese do not feel moved enough to intervene on the actions decided upon by that country's government. They might "care" and have some empathy for the resulting negative outcomes, but they would be insufficiently empowered to actually act.
Unfortunately, at least with the first point, this is true for a lot of people, and governments. This "they're not doing it, so why should I?" is a common justification, and is expressed in goverments who are pressured into ignoring environmental concerns because it could impact short term gains. India noted at the UN climate summit it had no intention of taking steps to move off coal power and that was a problem for others [1]. Granted, I agree it seems far-fetched to think this would extend so much as to aggravate the destruction of the earth's environment as stated above.
I think he's saying that we're already succeptible to moral hazard in the same way that we would be if we colonized mars. People in America don't have much skin in the game when it comes to protecting the environment in India or China.
Except, we still do care if their water is toxic and if the air conditions are poor. The same sort of empathy will apply to people on other planets as well. Even though a heavily polluted other planet doesn't directly affect us in the same way that a heavily polluted Earth affects us, we are currently pretty well isolated from the extreme conditions in Shanghai and yet we still care what happens there.
Furthermore, because of the large costs of shipping between planets, most of the things causing pollution on one planet is probably benefitting almost exclusively the residents of that planet.
Moral hazard is an interesting concern but I don't think that it's going to end up being a severe problem.
I'm taking the attitudes you suppose might exist in the future and translating into your current context, with the intent of showing that once you consider them concretely they don't make much sense. The United States isn't going to go "Oh, it's OK if everyone on Earth gets nuked, at least our Mars colonies will still be there." anymore than you're going to be unconcerned about whereever you live getting nuked because some other chunk of your country will probably survive.
It doesn't make sense to look at total emissions, though. Because then you can create arbitrary groups and demand that they scale down. Should Europe cut emissions because they're so high or is it okay for Germany to stay at current levels because they're so low? Either per unit land area or per capita are better measures.
The point is that if the Chinese had the standard of living that Americans have, everything would shoot through the roof. And considering that they don't, there's great potential for it to go wrong.
The whole "China shoving CO2 into the atmosphere" could just as well be stated "Americans driving large SUVs that dump CO2 into the atmosphere". It doesn't matter, we've all got to do our part.
What matters to the planet are the totals, I agree with your point that Americans have standards of living that needs to be improved, but I don't buy the argument that measures should be per unit land or per capita, because this is not the case.
A large SUV won't dump as much CO2 as industrial manufacturing, for example.
Naturally what matters to the planet are the totals, but not going per-capita or per-unit-area is asking a disproportionate share from different people. And you can frame the problem using different groups in different ways so it is no longer well defined. Observe:
1. Members of the OECD must cut down on CO2 emissions. They far exceed China's emissions. Totals are what matter, and the OECD certainly has a higher total than China. China can't do anything so long as the OECD keeps pumping CO2 freely into the atmosphere.
2. North America must cut down on CO2 emissions. They far exceed that of South Asia.
We can think of it this way. A certain standard of living requires some degree of pollution + cost. It is not productive to ask the other guy to endure a poorer standard of living while you live large just because he, as an individual, lives in a place with more individuals. You can ask for that, but it isn't going to happen.
The distinction is important, because coal is seen as a cheap way of feeding China's relentless appetite for growth (or more specifically, the appetite for the perceived advantages brought by this "growth" to those who are in a social or political position to benefit from it.)
Or even more specifically, the appetite for capitalising on the rest of the worlds appetite for growth. Let's not forget what region of the world production of our physical goods is outsourced to.
Personally, I don't care much about conserving energy specifically because so many others are not going to. The existence of large numbers of undersea vents makes me somewhat apathetic about the risk of humans "killing all life on earth". We could have full scale nuclear war / winter and I don't know if they would notice.
The latter is probably true but not germane. Nobody else was talking about sterilizing the planet, and there are many much less severe possible futures that still qualify as nightmare scenarios. Some of them could even conceivably happen, unlike total sterilization.
I think it is correct to be apathetic about the risk of killing all life on earth because that is far beyond our ability. Killing most life on earth and causing mass extinction is another matter.
Are you personally currently environmentally apathetic because you know somewhere there are some unspoiled mountain lakes that are still hardly touched by the hand of man?
Are you personally unconcerned about the possibility of your home being nuked because thank goodness Alaska will probably survive?
You hypothesize a very bizarrely precise self-interest that very suddenly gives way to complete wild suicidal abandon at a very precise point. I'm not at all convinced what you've ordered up here can exist.