The Earth’s Support of Life
The Earths carrying capacity is determined by constraints on natural resources and the impact of human actions. The earth’s resources are finite and can only support life to a certain degree. Experts on the topic have raised concerns over uncontrolled population growth and its impacts on natural resources. Currently, there are seven billion people on earth, the highest number ever. In addition, the global population doubling time has reduced drastically, from 160 years in the Middle Ages to 12 years in the 21st century. As scientists try to answer this question, it is clear that the earth has limited availability of freshwater and food. Due to the finite nature of earth’s resources, it cannot support a global population of more than 10 billion people.
The earth cannot feed an infinite number of people due to constraints on the amount of food it can produce. Population biologists Joel Cohen of Columbia University estimates that the 3.5 billion acres of arable land on earth can only produce 2billion tons of grain at full efficiency, which is enough to feed 10 billion vegetarians. Considering that not every individual is a vegetarian, the earth’s grain production capacity at full efficiency is likely to fall below the amounts necessary to sustain 10 billion people (Cohen, 1998). Due to limited amount of arable land, the Earth cannot feed a global population exceeding 10 billion people.
The amount of fresh water available globally is not enough to sustain life if the population went above 10 billion human beings. Though the earth is made up of 70 percent water, only 2.5 percent of it is fresh water. In addition, 70 percent of all fresh water is found in frozen form, trapped in the ice of Antarctica (Barlow, 2010). The remaining 30 percent is found in aquifers or as part of soil moisture deep below the earth’s surface. The amount of water available to human beings on a sustainable basis is less than 1 percent of the total fresh water on earth. The 7 billion people on earth use 30 percent of renewal supply of water. Researchers estimate that a global population of 9 billion people would use an unsustainable 70 percent of renewal water available.
The global nitrogen cycle is unable to support a large global population. Nitrogen is an integral part of any ecosystem. It is a component of numerous bimolecular compounds including proteins, DNA and chlorophyll (Galloway et al., 2008). Human activities affect the nitrogen cycle and affect its bioavailability. Nitrogen is available as dinitrogen (N2 ) molecules in the atmosphere. However, in this form it is inaccessible to living organisms. The nitrogen cycle is responsible for converting atmospheric nitrogen into its numerous oxides, which increases its bioavailability. Nitrogen’s inaccessibility makes it a scarce resource in the propagation of life. Experts note that the global nitrogen cycle would not sustain a high population.
The earth’s limited resources cannot support a global population exceeding 10 billion. Using the current food production methods, water supply, pollution and availability of arable land, a high population would exceed the earth’s carrying capacity. Fortunately, the global population growth rate is declining. The earths 3.5 billion acres of arable land cannot produce enough food for a population exceeding the Earth’s capacity. In addition, the available fresh water supply on earth is constant and cannot support these population figures. The amount of pollution produced by this population would reduce the earth’s carrying capacity. Due to the finite nature of earth’s resources, it cannot support a global population of more than 10 billion people.
Barlow, M. (2010, June). The global water crisis and the commodification of the world’s water supply. In International Forum on Globalization.
Cohen, J. E. (1998). How many people can the earth support?. Bulletin of the American Academy of Arts and Sciences, 25-39.
Galloway, J. N., Townsend, A. R., Erisman, J. W., Bekunda, M., Cai, Z., Freney, J. R., … & Sutton, M. A. (2008). Transformation of the nitrogen cycle: recent trends, questions, and potential solutions. Science, 320(5878), 889-892.