Optimizing for "green" is not what we're trying to achieve here. Mountains get greener when the tree line climbs as a sign of it's ecological decline. Stable forest and weather systems, biodiversity, bioavailability of nutrients in the ground are things closer to the interest of ecological causes.
Before is was physically possible for humans to change the climate most of the northern hemisphere was covered in a 4km thick sheet of ice. Then it melted and now there are forests. This melting also happened completely naturally and wasn’t because the cave men were putting out too much CO2.
This was done by the natural processes of the Earth, so recently even humans were alive during the Ice Age. Some scientists even say that we are due for another ice age, that we may be otherwise avoiding due to climate change.
Humans were around for the ice age, but not any of the humans I know. That was about 4 degrees Celsius, right? Over thousands of years. Meanwhile, my mom has lived through about 1.5 already and will probably see 2 in her life. Hell, depending on the breaks, I might live to see 3. Compressing a geological age into a human lifetime is bound to have some wacky effects. I can’t imagine being a kid today and thinking how much they’ll live to see.
