“ Here’s the thing about the stratosphere, the region between six and 31 miles up in the sky: If you really wanted to, you could turn it pink. Or green. Or what have you. If you sprayed some colorant up there, stratospheric winds would blow the material until it wrapped around the globe. After a year or two, it would fade, and the sky would go back to being blue. Neat little prank.”
Tell that to the crazy billionaire who triggered a massive algae bloom by dumping tons of iron sulfate into the ocean. The problem is that there are people who don't wait for proof of concept before doing something planet-altering.
I read an article the other day about whale populations that was talking about iron dumping being a possible solution, whales fertilise their own habitats by shidding out iron from iron rich areas, this leads to phytoplankton blooms which leads to krill blooms which the whales then eat and then shid out again elsewhere. Basically whales were already doing this before we killed most of them and they do a much better spreading job than we can just dumping it haphazardly, I think we will see a push to encourage whale population growth for this reason.