If the USA, Russia or any other nuclear power does it there won't be a war. Nuclear is the key word here, Those wars are much more costly than any amount climate change.
Maybe we should focus on ocean fertilization with iron as a way of increasing fish yields. Who can begrudge some poor fishermen trying to bring home more fish? It's not their fault if it also sequesters CO2.
Solar radiation management also offers possibilities though. We already spew lots of soot and other pollutants into the air without anyone rolling out missiles. We just need to figure out industries with the right kind of pollution and we're good.
This view is also a specist one, what about all the other lifeforms on the planet that we could not have life favorable condition on earth ? insects, plants, ocean life, corals, etc.
Switch from compete to cooperate mindset and there would be a lot less lifeforms rights violations. Also instead of having the USA lifestyle as a model we try try to reach and have for ourselves, we should aim for the India lifestyle so we could all live on earth without destroying the planet.
How about this: Are people allowed to act in a way that will save themselves, even if it sames everyone else on the planet, and has some side effects? I think the answer is an emphatic yes!
Who decides which ways will save and are therefore allowed?
If I pull off some massive project like this what is another person/business/country going to do about?
If someone "solves" climate for some value of solved are you going to invade them and start a war over your economy being saved?
Am I understanding you correctly?
When it comes to saving countless lives, the economy and in the most extreme of possible outcomes all civilization... YES.
Your attitude is dangerous, because you can use it to justify anything (e.g. you think you're about saving lives). It is evil, because it places you above everyone else and leads to death (e.g. you think you're saving civilization, which requires destroying the bad parts of it).
You either have not learned from history, or have learned the wrong lessons from it and are following in the footsteps of millennia of anti-heroes.
Something on this scale would be pretty much impossible to pull off if all the G-8 countries put you/your company on an embargo list for high tech materials.
It helps to be claiming to be acting in humanity's best interest instead of obviously being a despot. Think about the political aftermath of interfering with someone claiming that they are trying to save the world and having a reasonable argument that is the case.
Someone attempting this would likely be in a major country and would likely have the approval of most of the countries. If the USA attempted no amount of embargos could stop them, the same with Russia and maybe a few other countries.
It is even possible that Germany, France, Israel or South Africa could pull it off with a little politics and clandestine dealings. They could delay politically and pester larger nations and demand UN actions while continuing development.
If the US and Russia were dead set on stopping they could with a few bombing runs from aircraft carriers. I don't think that is likely because neither of these countries is crazy and would love to be saved at no cost while having a political bogeyman they can use in the future.
EDIT - Have an upvote for a thoughtful and reasonable reply though.