>>2857160No because first of all, volcanos release a ton of pollution apart from merely SO2 that harm the local environment. Also volcanos only release a fraction of the SO2 into the stratosphere, while the majority remains in the troposphere.
SO2 based cooling works best when its released in the stratosphere because that results in even spread worldwide, much less atmospheric reactions, and much less acid rain. Also most importantly, SO2 released in the stratosphere lasts 1-2 years before falling down, while tropospheric SO2 washes away in days.
Btw SO2 is just one candidate because its so cheap and easy, you can also use calcite, or coated silica particles which have even less side effects.
And if you're wondering about the side effects of SO2, the answer is that 10 million tons of SO2 per year evenly spread worldwide is just 20% of annual SO2 emissions, and because its so spread out, it practically results in no acid rain. It only has a slight effect on ozone levels.
But more importantly you need to realize the massive amounts of human lives and money saved from "fixing" global warming. Just for air-conditioning alone, it's estimated that reducing global temps by 1.5C will save $20-$40 billion in AC electricity usage, and that number saved will increase as the third world increasingly uses more AC.
Also the decreased disaster frequency and intensity will save trillions of dollars. And millions of human lives will be saved. There is also the psychological benefit of cooler temps in summer which will improve human mood and productivity.
If SO2 is still a concern (and it shouldn't be) then you can simply spend a bit more and use calcite or coated amorphous silica instead.
There is literally no reason not to do this already, I suspect some very hot Global South country like India or Indonesia will eventually do this on its own if global warming isn't stopped quickly enough. Maybe China will take it up as well. But there are also Western startups that are planning to do this, and there's an increasing
push among the scientific community to start doing geoengineering as soon as possible.