I think there was a mention in one of the ipcc reports where they actually ran the numbers and concluded that no amount of terraforming (be it forests, algae, a

I think there was a mention in one of the ipcc reports where they actually ran the numbers and concluded that no amount of terraforming (be it forests, algae, and some other hypothetical "negative" emission approaches), even ignoring economical or technical feasibility, would be able to stop or reduce ghg concentrations.