Ozone reacts with and degrades chlorophyll and photosynthetic enzymes, and thus lowers the plant's productivity.
Ozone reduces photosynthetic efficiency by competing with carbon dioxide.
The fossil record suggests that high temperatures and carbon dioxide concentrations have been correlated for more than 100 million years. During the last 100 million years there has been a general upward trend in carbon dioxide concentrations. For the last several million years, carbon dioxide concentrations have stabilized to fluctuate within a range of 180 ppm and 270 ppm d. The fluctuations in carbon dioxide concentrations match the glacial cycles. All of the statements are true.