Given two areas with equal sunlight and available water. Area I has a high amount of atmospheric carbon dioxide while Area II has a low amount of atmospheric carbon dioxide. How does the rate of photosynthesis in Area I compare to that in Area II? Atmospheric carbon dioxide has no effect on the rate of photosynthesis. The rate of photosynthesis increases with a decrease in carbon dioxide. The rate of photosynthesis increases with an increase in carbon dioxide. The level of carbon dioxide increases with the level of available oxygen.