Are you serious about cleaning up Old Momma Earth?
Do you really want to stop her turning into the ecological equivalent of an emphysemic Glaswegian, and have the skies full of birds and the seas full of fish? At little or absolutely no cost whatsoever? Enabling us all to get on with our lives, and putting the tedious, dull, boring 'global warming' debate to bed (and George Monbiot out of business) once and for all?
Then start studying the effect of spreading iron into the oceans.
It's all to do with the plankton, y'see; a life form as intellectually advanced (and as highly evolved) as many Greens.
Hat tip Dennis Mangan, Sage of Santa Rosa.