You said you needed help with the story, so... :
First of all,
Global Warming is not caused by Ozone depletion...
That would be UV radiation (remember those screwed up frogs, and all that skin cancer in Australia?)
Scientists now say that CO2 is the cause of Global warming, though only a small amount of it exists in our atmosphere, and hardly any comes from humans.
Basically, Global Warming has nothing to do with Ozone depletion, or humans...
I'd change that bit...
oh and also:
Traveling at near light speed would not get you anywhere fast, and it would pretty much cause you to jump into the future. Basically, if you went to visit a distant star, and the journey took you about a year, 100 million years would have passed back on Earth...
The only plausible science fiction thing on space travel would be a hyperdrive, which basically would create a wormhole and travel through hyperspace (bending the 4th dimension).
Still, that makes no sense unless anti-matter were to be used to power the wormhole creating device... as when positrons and antiprotons are added to normal matter, it gives off an extreme energy, something greater nuclear fission can do. still, anti-matter is difficult and time consuming to make...
so...
Unless your nanoparticles can make and control antimatter, space travel = nada.
(Plus who the hell knows where a wormhole will come out, it might even be in a different time, and ALWAYS in a parallel universe.)
so... good luck with the scientific relevance...
Read up on superstring theory and M-theory before you try and space travel, wormhole travel, or anything of the such...
nanoparticle idea sounds good though...
personally, I would make Velion turn into a black hole, but thats just me.