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About the space faring civilization I'm completely against this idea: it is a fairy tale aimed to distract the attention on the sad fact we are destroying our dear blue planet: "Ok we failed with this planet, let's try another one" is not what I'd call a progress. If longer term survival means to live into a metal box on the surface of Io or Europa, I'm not volunteering
As indicated by the Total Perspective Vortex, it's hard for us puny humans to get our head around the vast time scales involved ... but, given enough time and peaceful cooperation on Earth, becoming a spacefaring civilization is not a fairy tale, it's a certainty. As for not enjoying living in a metal box on Europa, your descendants will be genetically engineered to enjoy that. :)
I doubt that a successful interstellar spacefaring civilisation will be Homo sapiens though. A new species, genetically engineered for longer life spans and living in high radiation, low gravity environments (and metal boxes on Europa) would stand a better chance of success. And being supported by an army of self-replicating AI robots would also make a huge difference (e.g. to build infrastructure on a terraformed Mars) ... albeit with a risk they'll turn against us and wipe us out.
I suppose we might try using these long time scales to persuade folks to please stop destroying our dear blue planet now, though I doubt boffins speculating on interstellar space travel would have any impact on our current global warming crisis.
I just took a peek at an estimate of our chances of survival which scarily predicts:
an informal survey of experts on different global catastrophic risks at the Global Catastrophic Risk Conference at the University of Oxford suggested a 19% chance of human extinction by the year 2100 ... enumerating the risks as:
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