Answer:
CO2 levels will dramatically increase as well as food level supply will decrease. Oxygen levels will decrease too.
Step-by-step explanation:
Plants take in CO2 and produce Oxygen. Without plants, they can't take in CO2, and it is a necessity for them to take it in. Plants would die. Food supply would decrease because plants produce glucose during photosynthesis. Glucose is a kind of natural sugar that will be lost. Plants produce fruits or vegetables, so if there are no plants then no food.
Hope this helps!