How is colonisation of other planets unrealistic? It's not like I'm saying we'll develop FTL travel and leave this galaxy/star system. Also, every innovation is considered Science fiction until it is actually done - that's called progress.
2100 is more than enough time to develop tools and technologies that make Mars' harsh climate more hospitable for human colonisation. As we speak, missions are being sent or already been sent to the moons of Jupiter and Saturn to find water and life.
I genuinely don't think climate change will be addressed until it's too late for most of mankind. Only wealthy advanced nations will have the resources to prepare for the looming disaster.
That's if we haven't already been destroyed by nuclear war or Super-intelligent computers.
As for renewable energy, Somalis haven't given any indication that they will ever set aside differences to achieve anything worthwhile. They are being ravaged by drought and famine in the 21st century when most other nations have food security. They will be the first to be hit by any further climate degradation.
That's the illusion of progress. Progress in certain fields has exploded, which tricks the laymen into believing progress has been across the board. I mean, look at this new fancy 4k stuff which is nothing like the 360p that was standard just a decade ago. But why don't you go take a look at the newest Boeing 747 and compare it to its counterpart of 77? You'll find they're practically identical vehicles. This is almost the case across the board with regards to most modern technologies with a few exceptions.
That's not even talking about the massively difficult theoretical problems plaguing science wherein many scientists are now wondering if some of these problems and riddles can even be solved by the human mind. Progress sadly does not continue infinitely into the future. There's only a finite number of low-hanging fruit. There's only so many ways you can re-engineer or optimize a fuselage.
This is what happens when you watch too many documentaries or read online blogs of what Hawking or Musk are now saying, and become far removed from the actual engineering hurdles. Go and speak to some aeronautical engineers. It will be sobering. The massive hurdles posed by radiation, ineffective shielding techniques, propulsion limitations, not to mention the actual detrimental effects of <g gravity on the body. Even if all of those problems were surmountable, where exactly is the profit motive or incentive to do all of this? Saying this would require a huge amount of resources is possibly the biggest understatement of the century.
As for renewable energy, if it actually becomes viable as some are hoping, it will be quite easy to import into Somalia.