Human Carrying Capacity


Human Carrying Capacity is a selection taken by the book How Many People Can the Earth Support? by Joel E. Cohen who was a professor and head of the Laboratory of populations at the Rockfeller University and Columbia University. Cohen has a trend in his novel to depicted in the Classic Edition Sources : Environmental Studies, Fourth Edition text, to express the carrying capacity as being able to balance itself out. This will be further discussed in this summary.

The excerpt of his novel starts off with a case study of the Easter Island. He describes this mystical island and explains its history based on scientists and explorers. It is said to have had a human population situated on the island during the year 690. Cohen says “The islanders were probably isolated form out-side human contact until the island was spotted by Dutch sailors in 1722.” It is also said that forests and freshwater sources were scarce by 1400, making the population decrease. Although, the population started to increase slowly during that time, it reached a maximum of 10,000 people in 1680. 100 years later, the population decreased to 2,000 people because of smallpox disease that came from returning Islanders that were slaves in Peru. Cohen suggests that the more the population grows, the more resources will be limited and the more the living conditions will worsen. He also says that the human carrying capacity is “conditional on current choices and on natural constraints”, meaning it could change every time we measure it because the earth is a biological ecosystem, meaning it is always adapting and changing. The excerpt finishes with a metaphor of the human carrying capacity on Earth, which is expressed with the physics of walking. Your legs and muscles are always in equilibrium with each other, Cohen describes. This is a metaphor for the Earth’s resources and the human population. They are both always in equilibrium; if one changes, the other one will change in consequence to the other. For example, if the population increases, the environment will become less sustainable. If the environment undergoes a severe weather storm that kills a certain amount of people in that area, the population will then decrease.




  1. What is carrying capacity?

Based on the book How Many People Can the Earth Support? by Joel E. Cohen, carrying capacity is a measuring tool to find out what is the limit population, or number, of something in particular. This can be the human population in the world for example. The carrying capacity will take into consideration the crops needed to feed the people, the freshwater necessary to hydrate these people, and the amount of land they need to live on in the world, and all other necessities in life. This measuring tool takes into play all these aspects because the carrying capacity is a measure of sustainability; therefore it will measure what is the maximum people there can be on this planet, to be fed and hydrated while making sure no resources will run out. The world has to be able to sustain the maximum of people calculated. The number can change, depending on the state of the earth’s resources. It will decrease when the earth’s resources are depleted, and it will increase as the earth’s resources are plentiful.



Bibliography :

Cohen J. E.; How many people can the Earth support?;  T. A. Easton (Ed.); Classic Edition Sources: Environmental studies (4th ed., pp. 169-172); New York, NY: Mc Graw Hill


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