Have we reached the Earth’s carrying capacity?  Well, perhaps I can offer my answer to this question by first defining carrying capacity and then establishing the Earth’s carrying capacity as assessed under current natural and social conditions.

As defined in The American Heritage® Dictionary of the English Language, Fourth Edition:

• car·ry·ing (kār’ē-ĭng) ca·pac·i·ty (kə-pās’ĭ-tē) n.  
  • The maximum number of persons or things that a vehicle or a receptacle can carry: a van with a carrying capacity of 12.
  • Ecology The maximum number of individuals that a given environment can support without detrimental effects.

As explained by the Carrying Capacity Network, a watchdog organization of sorts, presenting “Real Solutions for America’s Problems”:

A common fallacy is to equate existing and seemingly open or “unused” spaces with the kind of resources and ecologically productive land needed to support human life under modern conditions. In fact, the criterion for determining whether a region is overpopulated is not land area, but carrying capacity.

Carrying capacity refers to the number of individuals who can be supported in a given area within natural resource limits, and without degrading the natural social, cultural and economic environment for present and future generations. The carrying capacity for any given area is not fixed. It can be altered by improved technology, but mostly it is changed for the worse by pressures which accompany a population increase. As the environment is degraded, carrying capacity actually shrinks, leaving the environment no longer able to support even the number of people who could formerly have lived in the area on a sustainable basis. No population can live beyond the environment’s carrying capacity for very long.

The average American’s “ecological footprint” (the demands an individual endowed with average amounts of resources, ie, land, water, food, fiber, waste assimilation and disposal, etc. puts on the environment) is about 12 acres, an area far greater than that taken up by one’s residence and place of school or work and other places where he or she is.

We must think in terms of “carrying capacity” not land area. The effects of unfettered population growth drastically reduce the carrying capacity in the United States.

In a post titled “Living Above the Line,” Environmental Research Foundation Precaution Reporter, Peter Montague, reiterated the assessment by the United Nations Environment Programme‘s fourth Global Environmental Outlook Report (GEO-4) in order to answer this question

…GEO-4 concluded that we humans presently require 22 acres per person to support our global average lifestyle — but, the report said, Earth has only 15 acres per person available.

In other words, we have already exceeded the Earth’s “carrying capacity” — it’s capacity to “carry” (or support) 6 billion humans. And the human enterprise is poised for a massive spurt of economic and population growth — expected to raise our numbers to 9 billion by roughly mid-century and to double the size of the human economy every 23 years….

Looking at the findings for the world as a whole presented in GEO-4, taking into consideration my own personal results I found in the ecological footprint quiz, and taking into consideration all of the other factors we have been discussing in People and the Environment lectures, such as the rate at which the Earth’s population is doubling, it is hard to argue against the fact that not only have we reached the Earth’s carrying capacity, but for many reasons we have long since exceeded the upper limits of population the global ecosystem can support.  However, I hope that we have recognized these statistics in time to correct the situation.  I believe the global society’s recognition of the mismanagement of our natural capital in time to continue to make strides toward a sustainable society, and setting and attaining hard and fast goals to meet sustainability, may provide the hope for our future and our grandchildren’s future.