Air pollution is killed with known measures, and it goes away as soon as these are enforced.
Climate change? We have literally changed the climate for the entirety of humanity's future unless we devise a system, whose energy requirements would overshadow practically anything we have ever invented and whose workings we still don't understand, and even so its impact would take decades, at the very least, to be felt.
I read once about an idea: to stimulate the growth of algae in the oceans by seeding them with iron. It would lead to an algae bloom which will die and settle on the ocean floor, trapping the carbon.
Yes, ideas that have been widely suggested as being extremely bad by adding even more uncertainty to already chaotic systems that are becoming destabilized.
If history is any indication, fertilizer runoff from rivers causes anoxic events in the ocean. That is shit is not to be fucked with; you can trivially destabilize an ecosystem and destroy it, as has already happened in many places.
Climate change? We have literally changed the climate for the entirety of humanity's future unless we devise a system, whose energy requirements would overshadow practically anything we have ever invented and whose workings we still don't understand, and even so its impact would take decades, at the very least, to be felt.