After 15,000 years, it's waking up

Plants use Co2 and produce oxygen, and the more abundant co2 the more they grow and thrive in nutrient rich soils.  There were experiments to see how much co2 is given back on the death of the plant... granted I don't remember if the study was a controlled burn or with composting.  But some test apparently yielded the result of hemp taking more co2 in than releasing it. If memory serves they said it was by several times more. Meaning it produced much more oxygen and pulled out more co2 than the other plants that were tested.  Ignoring that  there is artificial means where people made a way to filter it out of the air some years back.  But it doesn't remove the dependency of plants and living things  to exchange oxygen with co2.  They might as well encourage large greenhouses in cities to help provide food if they want to balance things.