>>2720386 The stoma of the plant lose water as part of their operation. This is a waste. It's why you can tie a bag around the leafy branch of a tree and get drinkable water at the end of the day.
The more carbon that is is the atmosphere, the less the stoma of any plant has to open to absorb the carbon. The whole point of photosynthesis is to utilize carbon to build carbohydrates and ultimately tissue.
Notice that none of the staves on your barrel are labeled carbon. That probably reflects on your education. But carbon and water are the major players in plant growth.