"at scale" it could be just as bad. C02 isn't poisonous the big problem we're dealing with is we're putting C02 from the ground in oil and coal and putting it into the air. We've been adding C02 that was NOT in the environment into the environment.
Yeah some water isn't a bad thing, but if all of a sudden we're adding from sources outside of the water cycle a LOT more water into the atmosphere you've got increased clouds, increased weather patterns, All of a sudden the inland portions of continents can start dumping as much water into the air as a warm ocean, that can DEFINITELY be a problem.