Earlier quoted context omitted.
We could start by running container ships on High Sulphur Fuel Oil. Same CO2, more cushion against Sun Rays.
We stopped high sulfur when we realized it was causing acid rain. CO2 is also acidifying the oceans, so there aren't a lot of things we can pump into the atmosphere without consequence. Best to avoid doing that altogether.
Coal AFAIK a bigger source of acid rains and world has not stopped using coal.