The Human Population and Carrying Capacity Essay

A population is a biological unit that represents individuals of a species in given area. On the same note, carrying capacity is the maximum number of organisms that can use a given habitat area without degrading it or causing social stresses which may result in the population being reduced. The population reaches the carrying capacity at the point where the per capita birth rate becomes equal to the per capita death rate. The book “The Future of Life” by Edward O’Wilson talks about the nature of life on earth, how precious biodiversity is and further highlights the significance of losing it. With this in mind, the essay discusses how the human population is quickly reaching capacity.

This discussion is mostly tied to Chapter 2 of the book “The future of life”. The chapter is named “The Bottleneck” and highlights the birth rate of humans and status of the human population by 2050. The author considers three scenarios and project values for the world population in 2050. Wilson first calculates the total number of people in the entire world when the birth rate is increased, decreased or remains constant and concludes that the population will approach 9 billion by 2050. In fact he matches up the rate of population growth to that of bacteria (Wilson, 2008).

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Projections show that the global population will estimate 9 billion in 2040 (U.S Census Bureau, 2009). Other sources estimate 2050 population at 11 billion (United Nations, 2008). The United Nations prospects that the population of developed countries will remain relatively unchanged with the exception of the US which is expected receive 44% growth whereas that of developing countries will rise to just about 7.8 million people by the year 2050. The carrying capacity of the world is estimated at around1 to 1000 billion (Cohen & Joel, 1995). According to David Pimentel, a sustainable economy without disaster can only be realised if the global population is decreased by two thirds (Global Footprint Network, 2009).

Wilson argues that the “ecological footprint” which is the average quantity of land needed by each person for basic necessities is approximately 2.1 hectares per individual for the entire world (2008). Human beings are however said to be using forty percent in excess of what the earth can generate in order to sustain the large population and this can be attributed to. On the same note, much as greed is a main factor to be considered, economists see the world as a place which can not be exhausted even with the ever growing consumption and production.

            Overpopulation mostly in developing countries has led more people to move to the urban centres from rural areas in search of employment, thus causing congestion in the cities and towns. This has consequently resulted in the growth of slums. It bears noting that poor sanitation in the slums has caused widespread of diseases because of poor hygiene like cholera, dysentery and typhoid. 12 million people die annually as a result of unclean water while another 15 million are killed due to polluted air (United Nations, 2008). On the other hand, presence of heavy metals and other contaminants has resulted in other adverse health effects. All this can be attributed to overpopulation.

            Food supply is very critical for any human being. Bearing in mind that human population is gradually attaining its carrying capacity, there has been the fragmentation of land and consequently, no meaningful agriculture takes place. Food supply required to meet the requirements of the entire population has become inadequate leading to starvation. This is a common phenomenon in underdeveloped countries where many people are undernourished, which is a clear indication of overpopulation. Statistics from the UN Food and Agriculture Organisation, FAO designate that the population of 64 out of 105 countries is higher than the available food supplies can feed Similarly 2 billion hectares have been degraded by population pressure (United Nations, 2008). The growth of biotechnology is also another indication that more methods are being sought to increase food production in order to cater for the population that is gradually exceeding the designated carrying capacity.

            Access to freshwater is also an issue of concern as a result of overpopulation. The percentage of water available for human consumption globally is only 1%. It is estimated that 48 nations with 3 billion people will experience shortages to freshwater by 2025 (Hinrichsen & Robey, 2000). The problem stems to deforestation which destroys water catchment areas and also global warming that leads to the melting of glacial ice which flows to seas and lakes. The result is that the little clean water available is accessed at a higher price. Poor people are thus denied access to clean water and may resort to unclean water for survival, this is yet another indication of the fact that human population is gradually getting to carrying capacity.

            Two out of every three animal species are currently estimated to be declining (Hinrichsen & Robey, 2000). The activities of human beings are the main reasons for this because human population is increasing at an alarming rate. These activities are on the increase without any signs of retreat in the near future. The increase in the demand for goods has resulted in the clearing of forests in order to provide enough land for development. Pollution is yet another cause of biodiversity loss and emanates from industrialization as well as urbanisation. Marine fisheries are also facing extinction as a result of overpopulation. Research has shown that marine life in oceans has declined considerably due to either overfishing or pollution of sea water.

The global climate change is also another indication that the population of the earth is quickly reaching carrying capacity (Hinrichsen & Robey, 2000). The growth of industries was sparked by the need to produce more commodities to meet the demand by increased population growth in an effort to sustain the population. This has however led to an increase in the number of green gases like carbon dioxide and methane that cause depletion of the ozone which shields the earth from harmful effects of ultraviolet rays from the sun. The situation is further compounded by loss of vegetation that would have absorbed carbon dioxide. In fact, Wilson calculated the theoretical amount of forested land that would have to be added to the earth to absorb all the carbon dioxide from the atmosphere in order to illustrate his idea (2008).

With the projected global population of around 9.1 billion by 2050, the earth may not seem to handle this number considering the present situation (United Nations, 2008). Already the inadequate food supplies, freshwater, access to public health and education are just but a few of the perfect indications that the population is so large that the earth can not handle. Unless necessary steps are put in place to contain the growing population, the future is uncertain. It is thus the responsibility of everybody to ensure that the carrying capacity is not exceeded.

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Cohen, & Joel. (1995). How Many People Can the Earth Support. New York: W. W. Norton and Company.

Global Footprint Network. (2009). Ecological Footprint Atlas 2009. Retrieved May 18, 2010, from Global Footprint Network:

Hinrichsen, D., & Robey, B. (2000). Population and the Environment: The Global Challenge. Retrieved May 19, 2010, from actionbioscience:

U.S Census Bureau. (2009). World POPClock Projection. New York: U.S Census Bureau.

United Nations. (2008). World population prospects: The 2008 population revision Database. Geneva: United Nations.

Wilson, E. O. (2008). The Future of Life. New Jersey: Paw Prints.