We have know for a long, long time just how important a ratio that minuscule amount makes. As you yourself just stated, if you cut the current minuscule amount

We have know for a long, long time just how important a ratio that minuscule amount makes. As you yourself just stated, if you cut the current minuscule amount to a lower minuscule amount, some plant species would die. And similarly, if you raise the current minuscule amount to a higher minuscule amount, the planet heats up and many animal and plant species will die. The balance required for the ecosystem that includes us took a long time to develop and stabilize. The huge rise in this extremely sensitive number has taken a minuscule amount of time (2 hundred years, not 2 hundred thousand or 2 million). A minuscule number making a huge shock to a huge ecosystem with a lot of inertia, the full effects of which have not yet been felt. But even without our help, I'm sure a new balance will eventually stabilize. And it will likely include humans. Our civilization is a little more fragile though, itself only having been around for a minuscule amount of time and only a global famine away from collapsing.