Like if we discovered spitting at a housefire would slow it down more than expected, it's still not preventing it from burning to the ground. It's just going to allow some asshat to say "See? Let's defund the fire brigade."
In any case it's certainly not spitting at a fire.
So this is completely viable, and then some! Even more so if one accounts for the fact that increases in CO2 are creating a substantially greener planet making this even easier.
I also don’t see anyone wanting to defund other efforts because trees make a difference. We may see local improvements, but I doubt we’d see global improvements such that anyone would think we’re home free. I could be wrong.
I see this as more of a quality of life improvement that could help make the inevitable bigger fight more bearable.