The term ‘carrying capacity’ is used to designate the maximum population that a certain habitat can support.
A square mile deciduous forest might maximally support a certain number of squirrels. An inland lake of a certain number of gallons might maximally maintain a certain number of carp. Those are examples of ‘carrying capacity,’ - the largest number of inhabitants which can be maintained without environmental degradation.
At one time, in the late 1960s and the early 1970s, the popular press and news media carried stories of the Earth nearing its total carrying capacity in terms of human beings. These reports had a certain “scare effect,” and there was talk of striving for “zero population growth.”
Although they were mere sensationalism, these media events do raise a legitimate question: is there an upper limit to the number of human beings which the planet can support?
Any number put forward as an answer to this question will necessarily be an estimate, and a rough one at that. The staggering number of variables in play, and their highly complex relationships to each other, are compounded by the constantly changing technology which allows for increasing food production.
In a sustainable and renewable way, without environmental degradation, how much food, clean water, and clean air can be available? How many people can inhabit planet Earth?
Reasoned estimates point to some number greater than 100 billion. But how much greater, nobody’s really willing to guess.
These estimates factor in a “first world” standard of living for the population: telephone, television, running water and other indoor plumbing, HVAC, electricity, etc., and around 200 square feet of indoor living space per person.
This is quite a rosy scenario, and much brighter than the doom and gloom presented by those who thought that a “population bomb” would soon cause global misery. (The Population Bomb was actually the title of a 1968 book whose authors believed that the Earth was near the upper limit of its carrying capacity.)
If the planet is nowhere near maximum population, then why is there hunger and famine? Why are there regions without sufficient water? Why is there poverty?
Those conditions are the result of bad decisions by people: a few honest mistakes, but mostly a lot of greed and corruption.
If the Earth’s population were 1,000,000 - which is less than 1% of what it is now - there would still be someone without enough proper food, without clean water, and living in poverty.
Even with only a tiny fraction of its current population, the planet would still be home to malnutrition, unclean drinking water, and poverty.
Surprisingly, as the population has grown, the percentage of people living in poverty has decreased. A larger percentage of the Earth’s population lived in poverty 4,000 years than now.
A steadily growing population (as opposed to a rapidly growing or erratically growing one) is the best environment for economic growth.
Interestingly, a “zero growth” population, or a declining one, tends to be worse for the environment than other populations. A smaller supply of young people - young workers - nudges industry to choose options which are not friendly to the environment, even when such technology is available, because such measures are labor-intensive.
