|@Domodedovo - The first problem is finding a suitable place to build a colony. Before going anywhere, you need to know where you're going. After that, it's a question of speed and distance. At 10% of light speed, a trip to Proxima Centauri (which DOES have an Earth sized planet, we now believe...) would take ~42 years. At 20%, 21 years. This isn't a short trip at all. And that's the nearest star. Of course, relativistic effects are more complex than that, but that's the scope of expansion, considering stars move around, but over very long time periods (the Sol and A/B/C Centauri system are going to be relatively this distance for the next few hundred thousand years, first getting slowly closer then slowly receding), but it's not impossible if we extend Human lifespans to ~120 years for this to be feasible.|
The trick is first identifying a target, then working on engines. Cryo-frozen test tube babies are probably never going to be the solution. You might bring such things along for genetic diversity, but you're going to need some adults to teach them (and for ethical reasons), and will have no shortage of scientist/researchers willing to engage in a multi-decade trip to be the first to do so.
First stop, though, is Luna and then Mars. Going farther is a bit hyper-ambitious until we get that part right.
@Martinr - My biggest problem with climate change proponents is that they engage in rampant hyperbole and that they reject realistic solutions because they REALLY just want THEIR solutions. In many cases, I believe these are well-meaning people that just get swept up in the tides of emotion and wanting to "do the right thing", but the politicians in charge of these movements do it for reasons of power and ideology, and I am under no delusions on that.
Realistically, we should be going for an all of the above approach, that focuses on adapting present technologies while developing new ones. For example, people have been pushing for all-electric cars for at least three decades now. Meanwhile, we've had hybrids for at least two decades. If we could get everyone into hybrids, that would cut carbon emissions by something like 1/3 to 1/2. But instead, we don't do it because of the relentless push for 100% electrics or bust.
Basically, it's a case of letting "the good be the enemy of the perfect", if you're familiar with that concept.
It's also trying to push a single "one size fits all" solution to the problem, which just doesn't work. Mass solar banks and mirror heating boilers work great in dry deserts for power generation (but they have wear and maintenance issues, of course), but don't work very well in higher latitudes due shorter days and a higher angle of incidence with the incoming solar rays. Likewise, geothermal works well, but only in certain areas (and can have detrimental effects on surrounding environments). Indeed, MOST "clean" power solutions require large landmass areas, meaning they have a bigger negative impact on the local environment and plant and animal species than even a super-dirty coal plants would, and wind turbines have (literally...) cut short the lives of a lot of birds, including endangered species.
Nuclear is a good solution for large power grids, but not for super small scale (though I believe people are working on that, and the holy grail of the fusion, rather than fission, reactor; for those who don't know, fusion has no waste [you're combining hydrogens into heliums], though it requires a lot of energy to kickstart it - atomic bombs are fusion bombs, which use an outer shell of fission bomb to compress the inside tight enough to initiate fusion, basically...) And I've seen some promising work on carbon recapture for natural gas plants, which would make them much cleaner while allowing for small scale operations.
But the biggest problem is small mobile things. While nuclear plants can be used for ships, and modular plants the size of 18-wheeler trailers are being worked on for bringing power to remote areas or disaster struck areas (scalable by putting several in parallel), when it comes to cars, you're stuck with fuel burning or toxic batteries that still have limited range. But if we could get a serious move towards hybrids, this, paired with the "all of the above" approach to stationary power plants to the cleaner nuclear, natural gas, etc, would make a huge dent in carbon emissions.
But as long as people are pushing for 100% clean or nothing...we get nothing.
It's really sad, because instead of meaningful chipping at the problem, we get nothing. And I thin that's @Glyn's point, too...?