This is known as the "green goo" scenario (grey goo is when nanites convert everything to nanites). Because, any plant that good is going to overrun everything else. You wind up with a world covered pole to pole with that plant.

There are lot's of stories about researchers trying to create "super plants" to end world hunger causing this. Stephen King might have even done one.

It's a very high risk strategy. Letting reforestation occur is a much safer plan. It just needs about 1/5 of our current farmland and a big drop in emissions for it to work.

I tried to visualize other solutions but this is the ONLY thing I could come up with that's actually doable. That really bothers me. Because it's starting to seem, like that/s the plan.