Answer:
More carbon dioxide gas would be found in the atmosphere.
Step-by-step explanation:
Photosynthetic organisms convert carbon dioxide in air to oxygen through photosynthesis, while other non-photosynthetic organisms only consume oxygen and release carbon dioxide through respiration, they do not undergo photosynthesis.
When the number of photosynthetic organisms on the earth decreased drastically, the carbon dioxide released from other non-photosynthetic organisms cannot be converted to oxygen, so carbon dioxide in air accumulates.