Atmospheric levels of carbon dioxide have rapidly increased since the industrial revolution. One effect of increased atmospheric CO₂ is global warming. What effect does increased CO₂ have on plants?
1) Increased CO₂ enhances photosynthesis in plants.
2) Increased CO₂ inhibits photosynthesis in plants.
3) Increased CO₂ has no effect on photosynthesis in plants.
4) Increased CO₂ leads to the death of plants.