as if it was an exam question.
actual answer, include some of these:
-photosynthetic material/plants will remove CO2 from the atmosphere
-these plants will use the CO2 to make glucose, plant respiration will release CO2 into the atmosphere
-animals will eat the plants (which contain carbon)
-animals and plants will eventually die and decay due to microbial/bacterial action releasing CO2
-the combustion/burning of fossil fuels will release CO2 into the atmosphere
-the burning of carbon based products made from trees will release CO2 into the atmosphere