whats the rundown on carbon emmision = global warming?

I'm reading that the current ppm is 400 and we add 1 every year.
I'm reading that high ppm stimulated plant growth, in fact if you are growing shit in a green house they pump carbon in so its 700-1000ppm depending on what you are growing.
I'm reading that ocean water absorbs carbon when its cold and releases it when its warm.

Seems like warmer weather = more carbon in the air not the other way around.