The idea that we can do something about it, i.e. by decreasing the use of fossil fuels, is based entirely on the idea that we caused it, i.e. by burning lots of fossil fuels. If we didn't cause it, the whole edifice crumbles.
> The idea that we can do something about it, i.e. by decreasing the use of fossil fuels, is based entirely on the idea that we caused it
That's a misconception you're holding onto. Those working on mitigating carbon in the atmosphere don't' care what the source of the carbon is. Whether we caused it or not simply doesn't matter.
> If we didn't cause it, the whole edifice crumbles.
The attempts to stop a calamity are worthwhile regardless of the original source of the calamity. Engineering the environment does not depend on whether we think we accidentally engineered it before.