Atmospheric Oxygen also Depends on Photosynthesis

We need to remember that mankind is part of the animal kingdom. The human species is as dependent as the rest of the animal kingdom on the plant kingdom. As human numbers have increased, an increasing fraction of the plant kingdom’s total productivity has been diverted from feeding other animals to feeding man or the animals man uses. One ecologist has estimated this fraction as one-eighth of the net production of the world’s land areas. Thus, with only three doublings of human numbers, we and our domestic animals would be consuming everything that grows on all continents and islands of the world, and eating it all just as fast as it could be grown and harvested. How many heads of government or members of legislative bodies have begun to face up to the implications of these numbers?

William R. Catton,

Overshoot: The Ecological Basis of Revolutionary Change (1982)

The concentration of CO2 in the atmosphere is not the only important gas. Oxygen, formed by photosynthesis is essential to all.