The chemical energy in petroleum collected from dead saltwater algae and was eventually entombed by Earth because bacteria hadn't yet evolved to eat all the dead algae. One way to reduce natural CO2 emissions is with antibacterials. About 4 ppm chlorine in the ocean water near the equator would shut down most plant food emissions.
We shouldn’t by any action reduce or eliminate CO2 in the atmosphere, even if we could, which I doubt is possible. CO2 is the foundation of life. It is the way carbon becomes the stuff algae, and all plants are made of. They become the food for all the rest of us. No CO2 no life.