How Much Population Can Earth Sustain?

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The purpose of this post is to provide some clues of the population growth impact on the environment.

Background information.

Nowadays the total human population on the Earth is currently estimated to be 6.92 billion. Human population is increasing with tremendous growth rate and scientists believed that in 50 years the number will reach to 10 billion as we can see on the graph below. So with the limited carrying capacity of the earth the problem of the overpopulation is obviously unavoidable. Carrying capacity is the maximum population size of the species that the environment can sustain.


Causes that increase the human population.

The basic factors that can determine the population growth are the birth and immigration rates that increase the size of the population and on the other side the death and emigration rates that decrease the size. So an easy way to calculate these rates is the specific formula:

Population Growth = Birth rates – Death rates + Immigration – Emigration.

(PG=B-D+I-E)                                                                                               (2)

Population growth theories.

Cornucopians are futurist who believe that human through the continued progress and the advances in technology will manage to face the problem of the over-population. Fundamentally they believe that there is enough matter and energy on the Earth to provide for the estimated peak population of about 9.22 billion in 2075.

Cassandras on the other side they believe that the overpopulation of the earth in the future will bring the world to an end. The earth will not be able to sustain the size of the population and unavoidably will have the extinction of the natural resources such as food and water and so on the end of the human species.

Now as far as my opinion, I believe that indeed humanity will face the problem of the overpopulation in the future and this will yield two different problems. The first is the matter of extinction of the natural sources and the second is the matter of extinction of space. So I think the problem of natural sources will be overcome with the rapidly growth of the technology. For example the creation of artificial products without the use of the natural materials such as pills that will replace the need of food and water by the human. But on the other side I believe that the matter of space extinction on the earth can be a vital problem in the future. The uncontrolled population growth will limited the space of living for every individual. Even nowadays we have extremely overcrowded cities that people face the problem of limited space and this will be even worst with the continuous population growth.

Paul Ehrlich.

Paul Ralph Ehrlich is an American biologist and educator who is the Bing Professor of Population Studies in the department of Biological Sciences at Stanford University and president of Stanford’s Center for Conservation Biology. He is known better as an ecologist and a demographer, specifically for his warnings about unrestricted population growth and limited resources. Ehrlich became well-known after publication of his controversial 1968 book The Population Bomb. (3) Ehrlich through his book focused to the mass starvation of humans in the 1970s and 1980s due to overpopulation, and advocated immediate action to limit population growth. The book has been criticized in recent decades for its alarmist tone and inaccurate predictions. Ehrlich stand by the basic ideas in the book, stating in 2009 that “perhaps the most serious flaw in The Bomb was that it was much too optimistic about the future” and believe that it achieved their goals because “it alerted people to the importance of environmental issues and brought human numbers into the debate on the human future.” (4)  However Ehrlich made a number of specific predictions that did not come to pass, for which he have received criticism. He have acknowledged that some predictions were incorrect but maintain that his general argument remains intact, that his predictions were merely illustrative, that his warnings caused preventive action, or that many of his predictions may yet come true.

(5)                                                                                                                                        (6)

     <–   The Author


The Book  –>




The I PAT equation.

I=PAT is the lettering of a formula put forward to describe the impact of human activity on the environment.

I = P × A × T

In words:

Human Impact (I) on the environment equals the product of P= Population, A= Affluence, T= Technology. This describes how our growing population, affluence, and technology contribute toward our environmental impact.

The equation was developed in the 1970s during the course of a debate between Barry Commoner, Paul R. Ehrlich and John Holdren. Commoner argued that environmental impacts in the United States were caused primarily by changes in its production technology following World War II, while Ehrlich and Holdren argued that all three factors were important and emphasized in particular the role of population growth. The equation can aid in understanding some of the factors affecting human impacts on the environment. (7)

How The  IPAT equation applies in various countries.


United States – The US with a population around 300 millions has a huge impact on the environment. The two major factors of the US is technology and affluence. By having these two factors on the highest grade, a developed country like the US can determine and influence the formation of the environment. Especially if the country’s consumption rate is as big as the US.

China – China being the most populated country in the world, having more than 1.4 billions, it is obvious that can affect in a big percentage the environment. China faces the problem of the overpopulation and that’s why is used strict governmental policies to reduce the growth of the population. The one child policy that China uses is an effective way to stabilize and control the population growth. So despite the huge technological growth that China has, the decrease of the population will eventually decrease China’s impact on the environment.

Greece – Greece’s population reaches around to 11 billion and in connection to a low affluence and even lower technological progress means that the impact of the country on the environment is balance between the average   and under the average rate.



Hans Rosling.

Hans Rosling is a Swedish medical doctor, academic, statistician and public speaker. He is Professor of International Health at Karolinska Institute and co-founder and chairman of the Gapminder Foundation, which developed the Trendalyzer software system. Rosling’s research has also focused on different links between economic development, agriculture, poverty and health in Africa, Asia and Latin America. He has been health adviser to WHO, UNICEF and several aid agencies. Also as chairman of Karolinska International Research and Training Committee (1998–2004) he started health research collaborations with universities in Asia, Africa, the Middle East and Latin America. He started new courses on Global Health and co-authored a textbook on Global Health that promotes a fact-based world view. (8)

Hans Rosling using the Trendalyzer software.

Hans Rosling using the Trendalyzer software. (9)

However it is interesting also to mention how Rosling presents and mixed many factors that contribute to the development of a country such as of economy, health and education.Rosling also aim on the interrelation of the developing countries with the developed and how these different economies are set up to achieve the specific progress. Such as the example of China that first developed a health policy before the economical growth that china has nowadays.













The Use of Food Production

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The purpose of this of this post is to understand better the role of food production on the enviromental and economical impact of a country.

Ecological Footprint is a measurement of the land and water amount required to sustain a population of any size. The specific measurement includes all the resources which people use for their daily needs and activities such as food, electricity, and other basic materials used for survival, theses should be balanced on this relationship between humanity and nature for greater sustainability.

Some important factors that determine the EF of a country is the carbon emissions through transportation and production of energy, that mainly occurs in the industrialized countries. And then the food consumption of the individual citizens that also occurs in developed and wealth. So mainly the rate of the EF of a country depends from the economical growth of the country such the United Arab Emirates with 10.68 EF and United States with 8.00 EF.

Also another important factor of the EF determination is the food that produced at distant places. For the transportation of this of food is used big amount of useless energy that is mainly gas and oil and furthermore this contributes to the pollution through the carbon emissions that yield by the transportation.


The Food Production In America.

As food production became more industrialized during the 20th century, several trends emerged. One trend was a loss in the number of varieties of crops grown. A second trend was the increasing amount of energy expended to store food and ship it to market. In some countries food may travel long distances to reach the market. In the U.S. today, food travels an average of 1,400 miles from the field to the table. The price American pay for the food covers the cost of this long-distance transportation, which in 2004 was approximately only one dollar per mile (1.6 km).

Assuming that you are an American (not all of us are in this class), you live in New York City (2009 population estimate 8,363,710), and that the average American eats 1 kg (2 pounds) of food per day, calculate the food transportation costs for each category in the table below (U.S. 2009 population estimates 307,006,550).

Consumer Daily Cost Annual cost
You $1.40 $511
Your class $28 $10220
Your town (New York) $11.709,194 $4.273.855.810
United States $42.980.917 $156.880.347.05

The ecological impact of food distribution.

  1. What specific challenges to environmental sustainability are imposed by a food production and distribution system that relies on long-range transportation to bring food to market?

A problem can be the wasted consumption of energy that is used for the food transportation, such oil and gasoline, and then the big amount of wasted food that is thrown away cause of the bad transportation conditions, if this hopefully doesn’t end up for regular consumption.One important solution in that problem can be the creation of productive food units inside the country and the support of local products which also will help the economical growth of the region.

The advantages of local food products.

  1. A study by Pirog and Benjamin (2003) noted that locally produced food in the U.S. traveled only 80 kilometers (appx 50miles) or so to the market, thus saving 96% of the transportation costs. Locally grown foods may be fresher and cause less environmental impact as they are brought to market, but what are the disadvantages to you as a consumer in relying on local food production? Do you think the advantages outweigh those disadvantages?

The disadvantages of the local products for the consumer can be the high prices of products cause of the high production costs, indifference to imported goods that are producing in underdeveloped countries with cheap labor force and low production cost. Also there is not a big variety of local products to satisfy the needs of consumers. However I believe that the advantages of local products are by far much healthier and in better conditions than the imported products but the only problem is the high price that cost.

The price of gasoline will “support” the local production.

  1. What happened to the gasoline prices recently? How would future increases in the price of gas affect your answers to the preceding questions?

With the price of gasoline on a continuous growth from year to year transportation have been obviously decreased or shifted to other kind of “transport-consumption “. This growth will unavoidably affect the cost of food transportation especially on the long-distance imported food. So the cost of the food will increase and as a result this will force the markets hopefully to shift their views on the local producers, and as an extent to the local consumers.

The difference between the Upper and middle class Countries.

  1. If you are an American, how do you think these figures apply to other countries or your country? Where do you base your assumptions.

In general terms more or less these figures applied to all western developed countries. However as I said before this depends from the economical growth of a country, thus United States as a better wealth fare state will have bigger consumption and waste emissions indifference with Greece that have lower economical abilities, and so lower buyer force to cope with high imported food products. So a shift to the local production can be helpful for all the “middle-class” countries such as Greece.



1)   (Organic Food cartoon 5 – search ID grin750)

2   ) (

Pirog, R., and Benjamin, A. (2003). Checking the food odometer. Comparing food miles for local versus conventional produce sales to Iowa institutions. Ames, IA: Leopold Center for Sustainable Agriculture, Iowa State University.

A Questionnaire for an Ecologist

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Chapter 1

This chapter is about describing the field of environmental science, the importance of natural resources and also understanding the scientific method and the process of science.

1. Environmental science is the study of how a natural world works, how our environment affect us, and how we affect our environment.

2. Which of these is not a NONRENEWABLE natural resources?

A. Coal
B. Natural gas
C. Fresh water
D. Crude oil

3. Environmentalism is not a social movement dedicated to protecting the natural world.

4. An experiment in which the researcher actively chooses and manipulates the independent variable is known as a….
A. controlled experiment
B. Correlation
C. Manipulative experiment
D. Natural experiment

5. Essay question
Discuss how our energy choices will influence our future enormously and give some examples.

6. Essay question
How our ecological footprint is related to the scarcity of natural resources?

7. Match the following steps of Scientific Method
a. First Step                     1. Predictions
b. Second step                 2. Observation
c. Third step                    3. Test
d. Fourth step                 4. Hypothesis
e. Fifth step                     5. Questions

8. ____ provide us the means to obtain and interpret information about the world around us.
a. Environmental studies
b. Social sciences
c. Natural sciences
d. Both a and b

9. Which of those of our planet’s ecological systems purify air and water,cycle nutrients and regulate climate?
a. Natural resources
b. Renewable natural resources
c. Ecosystem services
d. None of the above

10. Which procedure is known for its essential part of the scientific process?
a. Correlation
b. Data
c. Natural experiments
d. Peer review


This chapter will help students explain the fundamentals of environmental chemistry and apply them to real-world situations and describe the molecular building blocks of living organisms

1. _______ are carbon atoms joined by covalent bonds and many include other elements.
a) polymers
b) hydrocarbons
c) organic compounds
d) macromolecules

2. Polymers are _______
a) large size molecules
b) long chains of repeated molecules
c) lipids
d) nucleic acids

3. Photosynthesis, light energy to chemical energy CO2 + H2O -> O2 + sugar
a) True
b) False

4. Synthetic polymers are not plastics.
a) True
b) False

5. Match the elements with their atomic numbers.
a) oxygen              1) 16
b) carbon              2) 26
c) iron                   3)  8
d) sulfur               4)  7
e) nitrogen           5)  6

6.  _______ is changed into potential energy to produce motion, action and heat.

a) Elastic energy
b) Heat energy
c) Kinetic energy
d) Chemical energy

7. What gives information about the history of past life?
a) evidence of bacteria
b) fossil record
c) chemoautotrophs
d) panspermia

8. Phytoremediation, which of the following is not advantage?
a) limited plants can be used
b) low impact
c) produces less waste
d) costs less than other methods of remediation


9. (Essay Question)
Explain how and why bacteria are very diverse?

10. (Essay Question)
Discuss why chemistry is crucial for understanding?


This chapter talks about how the evolution influenced the diversity , which are the reasons for the extinction of animals and the population ecology and characteristics.

1. Match the following…

Biological Evolution  ( )     1. Species formation due to physical separation of populations

Artificial Selection  ( )           2. from populations that become reproductively isolated within
the same area
Adaptive Trait        ( )           3. A trait that promotes reproductive success

Sympatric speciation  ( )      4. The process of selection conducted under human direction

Allopatric speciation ( )      5. Genetic change in populations of organisms across generations

2. (Essay question)
Describe what Biological Diverisity is and analyze it’s parts.

3. (Essay question)
Use the LINCOLN – PATERSON Index for the following :

John made a research on the total population of rabbits in a sertain forest, in his first trip he marked 30 rabbits , on hes second trip he marked 60 rabbits in which only 18 of them were marked from the first trip.What is the total population of rabbits?

4. The Extirpation is the disappearance of a particular population from a given area, but not the entire species    globally
a) TRUE  ( )                        b) FALSE ( )

5. After every mass extinction the biodiversity NEVER returned to or exceeded its original state.


6. Whats is a Biosphere?
A. Communities and the nonliving material and forces they interact with
B. Interacting species that live in the same area
C. The total living things on Earth and the areas they inhabit
D. The environment in which an organism lives

7. What is a Natural Selection?
A. Traits diverge in two or more directions
B. The process by which traits that enhance survival and reproduction are passed on more frequently to future generations than those that do not
C. The process of selection conducted under human direction
D. The process by which organisms actively select habitats in which to live

8. What is a Habitat?
A. The environment in which an organism lives
B. Studies living (biotic) and nonliving (abiotic) components of systems to reveal patterns
C. An organism’s use of resources and its functional role in a community
D. the likelihood of death varies with age

9. What is the Population size ?
A. Spatial arrangement of organisms within an area
B. The relative numbers of organisms of each age within a population
C. The number of individuals within a population per unit area
D. The number of individual organisms present at a given time

10. Which of the following describe mortality?
A. Births within the population
B. Arrival of individuals from outside the population
C. Deaths within the population
D. Departure of individuals from the population


This chapter talks about the communities on the planet and the interactions between them.

1. How energy passes through trophic levels
A. Modifying the environment
B. Interaction
C. Removal
D. None of the above

2. What can you can Pioneer species?
A. The first species to arrive in a primary succession area
B. Species that have extincted
C. The predators of a primary succession area
D. The last species to arrive in a primary succession area

3. Biodiversity or-biological diversity is the variety of life in all its forms,levels and combinations, including ecosystem diversity, species diversity and genetic diversity.

4. Match the following:
Fundamental Niche ( )           1. Species divide shared resources by specializing in different ways

Realized niche    ( )                  2. When an individual fulfills its entire role by using all the available resources.

Resource partitioning ( )         3. The portion of the fundamental niche that is actually filled

Co-evolution       ( )                  4. Organisms live in a close physical contract

Mutualism         ( )                    5. Prey and predator become locked in escalating adaptations

5. What is a Food Chain?
A. Energy flow in a community
B. Energy transfer up the trophic levels
C. Feeding relationships and energy flow
D. None of the above

6. What is the most important category in Species interactions?
A. Predation, parasitism, and herbivory
B. Competition
C. Mutualism
D. All of the above

7. Predators at high trophic levels can indirectly affect populations of organisms at low trophic levels

8. Symbiosis is the ….
A. The living organisms of an area can’t live together
B. Species divide shared resources by specializing in different ways
C. Mutualism in which the organisms live in close physical contact
D. All of the above

9. (Essay Question)
Discuss George Orwell’s quote which he wrote in his nover Animal Farm, “Some animals are more equal than others”.
Explain what he meant and give some examples to it.

10. (Essay Question)
Describe how species can change communities.


This chapter will help students characterize the influences of culture and worldview on the choices people make and outline the nature, evolution, and expansion of environmental ethics in Western cultures

1. Match the following:
a) capitalist market economy                  1) the government determines how to allocate the resources
b) an individual’s/group’s beliefs

about the meaning of the world               2) worldview
c)  centrally planned economy                 3) buyers and sellers interact to determine  prices and productions

of goods.
d) subsistence economy                            4) costs or benefits    involving people other than the buyer or seller
e) externalties                                           5) people get their daily needs directly from nature they don’t

purchase or trade.

2. _______ is knowledge, beliefs, values, and learned ways of life shared by a group of people.
a) worldview
b) culture
c) community
d) ideology

3. Which of those perspectives is not in Wester ethics?
a) anthropocentism
b) ecocentrism
c) ecofeminism
d) biocentrism

4. Environmental justice is the fair and equitable treatment of all people regarding environmental issues.
a) True
b) False

5. Net Economic Walfer is based on income, wealth distribution, resource depletion.
a) True
b) False

6. What Green taxes do?
a) uses surveys to determine hoe much people are willing to protect a resource
b) penalize harmful activities
c) modify neoclassical economics to increase efficienty
d) discharge outputs of waste

7. Centrally planned economy = _______ ?
a) governments intervene to some extent.
b) people get their daily needs directly from nature they don’t purchase or trade.
c) the government determines how to allocate the resources.
d) buyers and sellers interact to determine prices and productions of goods.

8. Which of the following is wrong? In capitalist market economies, governments intervene to…
a) provide social services
b) manage the commons
c) mitigate pollution
d) not provide safety nets

9. (Essay Question)
Which factors shape worldviews? Classify them.

10. (Essay Question)
Explain what Neoclassical economics are about.

Concluding, this assignment was something new and challenging,it tested our knowledge so far and plus it helped us understand better the material. Also the assignment improved our ability to work as a group and in the same time we understood how difficult it is to organize such a test.

Human Consumption = Nature Jeopardy




The majority of humans that reside on this Earth thousand years before and until now have as a basic source of living the natural resources. People use natural raw material to cover their needs and activities. However limitation of these sources pushed humans to set a measurement of human demand on the Earth’s ecosystem. This measurement named ecological footprint. The specific measurement “represents the amount of biologically productive land and sea area needed to regenerate the resources a human population consumes and to absorb and render harmless the corresponding waste. Using this assessment, it is possible to estimate how much of the Earth (or how many planet Earths) it would take to support humanity if everybody lived a given lifestyle.” (1)




So as it is obvious Ecological Footprint has a vital role in the sustainability of natural resources. But there are two important factors that influence EF, and these are the population size and the overpopulation. The size of a population that a specific environment can sustain, named Carrying capacity and is granted as an ecological term. “The carrying capacity of a biological species in an environment is the population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment. In population biology, carrying capacity is defined as the environment’s maximal load.” (1). Furthermore when the results of the carrying capacity are negative and there is no limited control of the population growth, then there is an issue of overpopulation that in ecology called overshoot. “Overshoot occurs when a population exceeds the long term carrying capacity of its environment” (3).

Ecological Footprint information per Country.

Ecological Footprint information per Country.


Analysing briefly the impact of Economy on Earth.

On the above table there is depiction of Ecological Footprint of various countries according to the Global Virtual University (GVU) research. The measurement of a country EF is based on the hectares per person. Then the measurement extended to the World Average and world area available proportion in connection to the GDP per Capital. As it is presented from the research, the EF of Bangladesh is the smallest in comparison with the others. Bangladesh despite the huge population rate that is 164.4 million is granted as developing nation with annual GDP per capital around 1700 with little affluence and little technology that depict a not completely developed nation. On the other side the UAE has the biggest EF despite it has much smaller population than Bangladesh. This happened because of the huge economic wealth that has as a nation, with a GDP per capital to 18,250. This means that there are much more possibilities for citizen of UAE to consume more natural resources that the citizens of Bangladesh, so as the consumption increases the impact on nature increases. The same thing happens to the Australia example.

Australia has also a high GDP and a  bigger EF from Bangladesh but lower than UAR, this affected by the fewer natural resources that Australia has in contrast to the fertile land of UAR. As it is obvious the economical wealth of a nation has tremendous impact on earth resources cause of the over-consumption of products. The loudest example is the United States of America that have one of the biggest EF in the world in extend of a capitalist society that based on materialism.


Man's expanding waistline matches increased ecological footprint

Man's expanding waistline matches increased ecological footprint



My Ecological Footprint.

If everyone on the planet lived my lifestyle, we would need:

My personal impact on the “Earth consumption” according to the seems to be huge in contrast to my country’s average which is 5.40. My EF proved 41.28, a tremendous percentage which I think  it must be wrong or used another kind of measurement. Cause as we see in the next picture my general statistics in the three categories of  carbon footprint ,Good and Services footprint and Housing footprint are much lower than my country’s average footprint. The totally negative category is my food footprint which is above the average. However  the choice of my food can’t have more negative impact than a carbon footprint so i find this measurement contradictory. (6)



To sum up, according to the above briefly research we can conclude that Earth face a big ecological problem. Most of the people, including me, don’t care so much about the impact of human living in nature cause the results will influence the living of the future generations. The over-consumption of natural products and energy disincline the sustainability of earth sources. The measurements of national EF disclose that countries with higher GDP are responsible for the biggest ecological abuse of nature.

A problem like this can controlled by stricter governmental or even better  transnational ecological policies that will impose large corporations to be friendly with the environment. So the issue of sustainable policies is aimed basically to the wealth  nations and not to the developing. However in my opinion, all these wealth nations should first provide a welfare state policies to their own citizens, cause as it is usually the wealth of states are on the hands of  privilege people and then should provide ecological imposes to their citizens. Cause an ecological disaster first will harm the poorest people of a country or even another poor county.


Sources :






Image Number: RPET868

Date: 2010-01-04

Artist: Roy Peterson




Tragedy of the Commons Hits Colorado River


The tragedy of the commons is the title of an article written by Garret Hardin in 1968. Garret Hardin was a major ecologist who warned on the dangers of human overpopulation. Hardin based on that focus his research on issues such as abortion immigration and sociobiology. His idea of the tragedy of commons is aimed to the idea of sustainability. Setting of the theory is applied to a non-renewable land resource that eliminated by individuals who over-exploit the source to increase their profits. Basically , the Tragedy of Commons theory aimed to the environmental protection through the sustainable development.

This is a short video that explain briefly the concept of the Tragedy of Commons.

The Colorado River is located in the southwestern United States and northwestern Mexico, the Colorado River is a 2,330-kilometer (1,450-mile) river with its headwaters in the Rocky Mountain National Park in north-central Colorado. The river is the primary source of water for a region that receives little annual rainfall.

The Colorado River rises in the Rocky Mountains of Colorado and flows into Utah and Arizona.

The Colorado River rises in the Rocky Mountains of Colorado and flows into Utah and Arizona.

About 25 million people are served by the approximately 1,400-mile Colorado River, the source of which is primarily snow melt from the Rocky Mountains. Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming as well as Mexico depend upon its waters. Though the river is tightly controlled, issues with water scarcity exist. In addition to a water supply, the river also generates hydroelectricity.

The Colorado River Basin offers a major renewable water supply in the southwestern United States. About two-thirds of the water flowing in the Colorado River and its tributaries is used for irrigation, and the other one-third supplies urban areas, evaporates into the atmosphere, or provides water to riparian vegetation. Without Colorado River water, the region would support few crops, and major cities such as Las Vegas, Nevada, and Phoenix, Arizona, would not have grown so rapidly. But today nearly 17 million people depend on the Colorado’s waters. The basin population has expanded dramatically in recent years, with most growth occurring in urban areas, where about 80 percent of the region’s residents live.



So there is an issue of environmental sustainability. The over-exploitation of the water of river will yield to a huge ecological disaster in the environment of the region. This will have a direct impact to the population a

Water Scarcity: Lake Mead on Colorado River

Water Scarcity: Lake Mead on Colorado River

nd the climatic change. In this situation Hardin’s theory of the commons is a good solution. The amount of water that every state deserve should be applied  with the use of stricter governmental regulations. Also another solution can be the run of a campaign fro

m ecological non-governmental organizations for the  environmental awareness of people of the region. Solutions like these will reduce the over-consumption of the water  and will provide better sustainability to the river and furthermore to the region.