19.5 Acres Per Person

Some people doubt that humans can have a significant impact on anything so large as the Earth. But a simple calculation shows that there's only enough Earth to give 19.5 acres to each person if evenly distributed. Of course, 70% of that is water, so that's nearly 6 acres of land and 13.5 acres of water.

Think you couldn't mess up 6 acres of land? That's pretty small, it's easy to mess that up. Back in 1750 there were 60 acres of land per person.

On top of each person's piece of the Earth sits 785 thousand tons of air. Each person now creates an average of 3.4 tons of new CO2 per year which works out to 4 parts per million. The data show that atmospheric concentration of CO2 has increased by about 1.3 ppm per year since 1958, but there are 3 times as many people as there were then. So nowadays we're putting out CO2 at an accelerated rate.

By contrast volcanoes only add about 0.025 tons ofCO2 to each person's share of the atmosphere each year. The human contribution of CO2 is 130 times that of volcanic activity.

All this is with only 6.5 billion people. The projected population peak is something like 10 to 12 billion people. Three acres of land per person, nearly 7 acres of water. That's bad. That's living on the hairy edge. With so little land per person, even a small event could cause a population crash, and we're on track to double the 1750 CO2 concentration by the time our population hits 12 billion.