Impact of population growth

The purpose of this blog is to discuss population growth and its impact on the environment. Key terms such as the IPAT equation and key figures such as Paul Ehrlich and Hans Rosling will be discussed to introduce the reader to the concept of population growth and its various consequences.

To begin with, watch the simulation in the following link to get an idea about the growth of population on global scale.

The world population exceeds 7 billion and as it can be seen in the simulation it is rising rapidly. However, it is not its rise in absolute numbers that causes scientists to worry as much as the fact that the population increases exponentially, meaning that the more the population increases, the faster its rate of increase becomes. To get an idea of the growth of world population during the past and what the growth will be in the future, given that people do not take measures, one just has to take a look at the following graph.

Pic 1.Population growth graph

As it can be seen from the graph above, after 1950 population started to increase rapidly. However, this increase is not equally divided between the developed (red) and developing (blue) world. Factors such as access to medicine, well-fare and resources, have led to a huge increase in the population of the developing world. These factors have also led to an increase in the developed world until about 2000. However, factors such as family planning and greater familiarization with contraception issues have led to a slight decrease of population after 2000. The following video can give you an idea about how we reached 7 billions (it was made in 2010):

Projecting the evolution of these variables into the future we  can see that the world population will continue to increase rapidly, reaching 9 billion around 2050. The question that inevitably rises is simple: how much more people can Earth support?

Concepts such as Earth’s carrying capacity have already been discussed in a previous post. However, deciding about the Earth’s future is not as simple as comparing these numbers. This matter, as it was natural, has been discussed in depth by various experts and two different “dogmas” have been created, each with different and opposing views about the future: Cassandras and Cornucopians.


The term cornucopian comes from the Greek mythology. According to the most famous myth, when Zeus was a baby he was fed and taken care of by a goat, called Amalthea. One day he accidentally broke one of its horns, which had the power to provide unlimited nourishment.

Pic 2.Image of cornucopia

In environmental terms, Cornucopians believe that no matter its numbers, humanity, with correct use of its technological resources, will be able to sustain itself and overcome problems in the future. Moreover, humanity will be able to conserve its resources, since technological advancements can help make more efficient use of them.


The term Cassandra comes, also, from the Greek mythology. Cassandra was the daughter of the king of Troy, Priam, and was blessed by god Apollo, who was struck by her beauty, with the gift of prophecy. However, when Cassandra rejected Apollo, he cursed her so that nobody would believe her prophecies. Cassandra is a tragic figure in the destruction of Troy, as she had tried to warn the people of Troy about the threat of the Trojan horse, yet no one believed her.

Pic 3.Cassandra

In environmental terms, Cassandras predict that “humanity is on a collision course”. The damage people have done to the environment is irreversible and we are doomed, since Earth is no longer able to sustain our growing population and needs.

The most important figure of the Cassandra “dogma” is Paul R. Ehrlich.

Pic 4.Paul R. Ehrlich

Paul Ehrlich, born 1932, is an American biologist and a professor at Stanford University. He is most well known for his book “The Population Bomb”, published in 1968, in which he predicts the end of human civilization by the end of the 20th century. The rationale behind this radical prediction was that the constant population growth would lead to higher consumption needs and thus depletion of resources, which would in turn result into famine. Consequently, wars would break out over the control of the resources and this war would lead to the end of civilization. Although this prediction may seem quite inaccurate, since we are still alive, numerous of his predictions regarding the environment have proved to be true.

The IPAT equation

Apart from “The Population Bomb”, Ehrlich is famous for the IPAT formula, which he created with professor John Holdren of Harvard University. This formula is used to calculate the impact of the three most important factors on the environment.

Impact(I)= Population(P) x Affluence(A) x Technology(T)

I= PxAxT

The formula is better described in the following video:

The IPAT formula is a very useful tool, since it allows comparison between countries that may differ significantly in various factors, regarding their impact on their environment. The comparison of the environmental impact of different countries follows:

USA (population of 308,745,538 according to the 2010 census)

Although the United States remain one of the most populated countries worldwide, it is not its population that is the determining factor in the IPAT equation. Technology and affluence are dominant and multiplied by its population result in a huge environmental impact. It has been calculated that if the rest of the world consumed as much as the average US citizen, Earth would be able to support around 2,5 billion people.

 (population of 1,339,724,852 according to the 2010 census)

Although China has made huge progress in terms of technology and affluence during the last decade, the determining factor of its impact on the environment is its population. Although China has applied the “one child policy” since 1978, its population is still increasing. This increase in population, combined with the rising technology and affluence have made China on of the countries with the biggest environmental impact worldwide.

Greece (population of 10,787,690 according to the 2011 census)

Greece’s population does not allow its environmental impact to be significant. However, its combination with the increase in technology and affluence result in a quite significant environmental impact for its small size. The problem Greece faces is that its population is declining. During the last 10 years, from the 2001 to the 2011 census, the population of Greece has decreased by 1.6% and this is a problem Greece needs to face immediately.

Hans Rosling

Hans Rosling (born 27 July 1948) 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. Using the Trendalyzer, Rosling creates animation of how data of countries have evolved throughout the years and using trend analysis, projects this data  in the future. His research is about the link between economic development and the growing population, focusing on developing countries, especially in Africa. He has been nominated as one of the “100 most influential people” by Times magazine in 2012. You can watch Hans Rosling’s speech on TED, below:

What impressed me more about his speech was that as countries progress in terms of economic activities, they tend to have the same behavior not only in terms of economics, but also in terms of population growth. Moreover, I found his “solution” to overpopulation of the developing countries extremely interesting.


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The purpose of this post is to introduce the readers to the concepts of evolution. Its purpose is to discuss this most important issue in simple terms and give information about the theory of evolution and its processes. Overall, concepts regarding the following image will be discussed.

Picture 1. Cliché “evolution” image (1)

The theory of evolution was first introduced by Charles Darwin in his book called “The Origin of Species” in 1859. The main idea discussed in the book is that populations evolve over the course of generations through a process of natural selection, which is the gradual, non-random process by which biological traits become either more or less common in a population as a function of differential reproduction of their bearers. (Natural selection will be further discussed later on.)

The idea of evolution was not a new concept. On the contrary, the concept of evolution can be traced as back as the philosopher Aristotle (4th century BC) and even the philosopher Empedocles (5th century BC). However, Darwin’s work is crucial because of the fact that not only did he discuss the concept of evolution in depth, but he also provided scientific evidence to support his theory.

The ideas of Charles Darwin challenged the idea that man was created by God and, as it was expected, were initially rejected from the scientific public of mid 19th century England. However, despite its initial rejection, Charles Darwin made concepts such as the evolution of species known to the wider public and sparked discussions in scientific circles.

Anyway, enough with the history of the theory of evolution. For more information about the life and work of Charles Darwin, you can watch the following video (3 parts), which narrates the biography of Charles Darwin in a humoristic manner.

Part 1

For parts 2 and 3 click on the links below:

Part 2 (8:35)

Part 3 (7:17)

So, what is evolution?

Evolution can be defined as the gradual development of something. Given that this “something” is a living organism, we refer to the process of its evolution as biological evolution, which is the change in the inherited characteristics of biological populations over successive generations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules, such as DNA. 

This simply means that there is a difference between the genetic information an individual receives from his ancestors and the genetic information this individual gives to its descendants (heredity). Naturally, this difference (mutation) is very small and its consequences can’t be seen. However, considering that this process is repeated for some million years, adding up these small differences may result to something completely different from the initial individual.

The main reason that this process occurs and that determines these small genetic differences that are passed on to our descendants is adaptation. Simply, we need to adapt to our environment and in order to do so we change bit by bit (variation). Naturally, the more drastic these changes are and the greater our need for adaptation are, these differences become bigger and changing more evident.

The most important means of evolution is natural selection. It is t he process by which genetic mutations that enhance reproduction become and remain, more common in successive generations of a population. Natural selection is often described as “survival of the fittest”, however “fittest” in the specific context refers to the best adapted to the environment species.

The concepts of natural selection, variation and mutation are explained in the following diagram.

Picture 2. Evolution through natural selection(2)

For a more detailed explanation of the concepts mentioned above, you can watch the following video:

Similar to the natural selection is the process of artificial selection. However, instead of nature taking care of the process of adaptation, humans intervene and actually create new breeds, or even species, that have desired traits of other species. Well, one might think of a mad scientist experimenting and creating monsters, however these “monsters” are really familiar to us, yet not everyone knows that they are a result of artificial selection. Some examples of such “monsters” are:

Picture 3. A Great Dane, a Pug and a Chihuahua (3)

Well, surprisingly enough, Chihuauhas, Pugs and Great Danes, as well as numerous other dog breeds, are a result of artificial selection.

So, concluding on evolution, species tend to adapt to their environment. This process, however, can take millions of years and if we don’t actually intervene, meaning the artificial selection process, we do not interfere in this process.

Well, not really. But actually, does the human impact on the environment affect the evolution of species?

Well, the answer is quite simple. Not only does our impact on the environment affect the evolution of species, but also we have accelerated this process, making its consequences immediate and easily identifiable. It would be easy to discuss the evolution of a microorganism as a result of environmental changes, however it would be as easy to forget it. So instead, the case of the Grolar Bear will be discussed.

Picture 4. A Grolar or Pizzly bear(4)

As the name suggests, the Grolar or Pizzly bear is a hybrid between a Polar and a Grizzly bear. They have a gray color and their size is between this of a Polar and a Grizzly bear. Generally, their characteristics are a mixture of the characteristics of both species, which differ significantly.

It was first observed in 2006 in the far north territories of Canada. At first scientists paid no attention. However, after some more appeared, they checked their DNA and they reached the conclusion that the Grolar bear is a mixture of the two species.

The reason that led to interbreeding is the environmental change, the result of which are evident in the Arctic. As the Arctic ice cap disappears, the two species have come to contact. The decreasing population of Polar bears has led the populations move to the southern territories of the Arctit. At the same time, the rising temperature has led Brown bears towards the northern territories of their habitat and thus the two species have come to contact.

Although this may seem harmless, or even good for the well-being of the species, it is actually quite dangerous and may even lead to the extinction of one of the species (most possibly the Polar Bear, as it is fewer in numbers). In similar cases in the past, one specie became subsumed to the other, with the rarer specie becoming extinct eventually. Moreover, scientists claim that as a consequence of this crossbreeding polar bears will adapt to higher temperatures, thus not being able to survive in their natural habitat.

The fact that this whole procedure has taken place during the past couple of decades can be at least concerning. The fact that we have accelerated a process that would ,under normal circumstances, last for hundreds of years so much that it took place in just 20 is at least frightening. Finally, the fact that except for the Grolar bear another 34 potential hybridizations have been listed, can only make us think of the consequences of our lifestyle and fortunately change it.


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  6. “Introduction to Human Evolution.” Human Evolution by The Smithsonian Institution’s Human Origins Program. N.p., n.d. Web. 15 Nov. 2012. <;.


  1. The New Diplomacy. N.d. Photograph. : The Evolution of Diplomacy. Web. 12 Nov. 2012. <;.
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    Dog Breed Info Center®, DBI. N.d. Photograph. Dog Breed Info Center®, DBI. Web. 12 Nov. 2012.                                                  <;.- Pictures of Cute Puppies and Dogs. N.d. Photograph. Pictures of Cute Puppies and Dogs. Web. 12 Nov. 2012. <;.
  4. Grolar Bears and Narlugas: Rise of the Arctic Hybrids | OnEarth Magazine. N.d. Photograph. Grolar Bears and Narlugas: Rise of the Arctic Hybrids | OnEarth Magazine. Web. 12 Nov. 2012. <;.

The purpose of this post is to make a comparison between what humans demand from their environment and what the environment is capable to supply. In order for such a comparison to be possible and meaningful, one must be introduced to the terms of Ecological Footprint and Carrying Capacity.

The ecological footprint is a number that expresses how much “nature” the lifestyle of a certain group of people requires. It depends on a number of variables, with the two most important being one’s country and one’s GDP. The ecological footprint expresses “the amount of land and ocean area required to sustain your consumption patterns and absorb your wastes on annual basis”. An easy quiz that estimates your Ecological Footprint can be found here.

The carrying capacity is the maximum population of a certain species that an environment can indefinitely, meaning that the environment can provide sufficient food, water and other necessities. For example, according to, earth’s carrying capacity for humans is anywhere between 2 and 40 billion people. The range is so wide because there are huge differences between the “lifestyle” of various countries around the world.

The term “lifestyle” may seem strange in such a concept. Although one understands what “lifestyle” stands for, it is rather difficult to make comparisons between different lifestyles and their impact on the environment. In order to make comparisons possible, one can compare between the most determining factor of “lifestyle”, which is the Gross Domestic Product of each country. This way, a direct relation between GDP and ecological footprint can be made, making conclusions about certain lifestyles and their impact  on the environment.

The following table shows the relation between the ecological footprint of each nation and its GDP. It also shows the proportion relative to world average and the proportion relative to world area available, which expresses the ratio between the needs of each country and the available area.

Country EF (hectares per person) – (data from ecological footprint) Proportion relative to world average Proportion relative to world area available Gross Domestic Product (GDP) per capita –(get data from CIA Worldfactbook)
Colombia 1.9 0.61 0.73(1.9/1.78) $10,400 (2011 est.)
China 1.84 0.59 1.03 $8,500 (2011 est.)
Bangladesh 0.6 0.19 0.33 $1,700 (2011 est.)
United Arab Emirates 15.99 5.16 8.98 $48,800 (2011 est.)
Uruguay 4.91 1.58 3.11 $15,300 (2011 est.)
Burundi 0.75 0.25 0.42 $600 (2011 est.)
Australia 8.49 2.74 3.09 $40,800 (2011 est.)
Nepal 1.01 0.32 0.57 $1,300 (2011 est.)
New Zealand 9.454 3.05 5.31 $28,000 (2011 est.)
World Average 3.1 1.0(3.1/3.1) 1.74(3.1/1.78)  
Greece 5.58 1.8 3.13 $26,600 (2011 est.)
India 1.06 0.34 0.59 $3,700 (2011 est.)
Germany 6.31 2.03 3.54 $38,400 (2011 est.)
Libya 4.36 1.41 2.45 $14,100 (2010 est.)
United States 12.22 3.94 6.86 $49,000 (2011 est.)
Your personal footprint 2.26 0.73 1.27  

As it can be clearly seen on the table above, if we consider GDP the independent variable, there is a positive relation between the GDP and Ecological Footprint, meaning that the more money an individual makes, the better living conditions he enjoys and the more he harms the environment. This observation is quite shocking, since one would expect that the more “developed” a country is and given that the respective society has solved all or more of its survival issues, the more it would care for its environment. This relation is made even clearer in the following graph, presenting the relation between GDP and Ecological Footprint.

One of the most interesting countries to discuss the relation between their GDP and Ecological Footprint, is Bangladesh. Bangladesh is a country in South Asia. Its population is about 160 million people, while its area is about 150,000 square meters, making it one of the most densely populated countries in the world. The per capita GDP of Bangladesh is $1,700, while its ecological footprint is just 0.6. This happens because Bangladesh is a “developing” country, meaning that the western lifestyle has not yet “infected” them. However, Bangladesh has shown a significant “progress” during the last years, meaning that they are embracing the western lifestyle and the western ecological footprint will inevitable follow.

A totally different case from Bangladesh is the United Arab Emirates. It is located in the Arabian Peninsula and its population is about 9 million. The per capita GDP is about $48,800, making it one of the richest nations worldwide. However, their ecological footprint, although they have not actually embraced the western lifestyle, is 15.99, one of the highest worldwide. The reason this happens is because of the extraction of huge amounts of oil, around which the whole economy of the country circulates. The high prices of oil, in addition to the less ecological concerned population has led to over exploitation of the natural resources of the country, thus giving such an ecological footprint.

Another interesting case is Australia. Australia is one of the most developed economies in the world and they have a per capita GDP of about $40,800. Australia’s ecological footprint is 8.49, which is about 2.5 times more than the world’s average. However, for a country with an industry that evolves around exporting commodities, such as gold and nuclear substances that require mining and are harmful to the environment, Australia has managed to preserve its unique ecosystem.

Greece is a rather disappointing case in terms of ecological footprint. It is a country of about 11 million people and the per capita GDP was about $26,600 in 2011, however it has decreased dramatically. Greece has an ecological footprint of 5.58. Although it may not appear as a very high GDP, taking into consideration that Greece is considered as one of the most “developed” countries worldwide, it is actually ridiculously high, since Greece does not produce anything. There is no industry in Greece, let alone heavy industry, and there are very few exports of commodities. Consequently, Greece has such an ecological footprint in order to cover its own needs. Given its population, one can understand the huge damage the environment suffers in order for us to cover our needs, such as energy needs, in ways that are possibly the most harmful to our environment. Moreover, things may get even worse since the efforts that had began before the economic crisis towards a more environmental friendly Greece have, naturally, stopped, since nobody would care for the environment given that he cannot cover his own basic needs.

After taking a quiz on, I found my EF to be 2.26, which actually surprised me. Although it is under the world’s average and way under the country’s average, it seemed quite high to me. Although I am not an keen environmentalist I tend to be careful about my attitude towards the environment, meaning that I recycle and I try not to consume more than I need. However, it appears that it is far from enough. If everyone followed my lifestyle, we would need 2.26 Earths to support us. What I understood from my EF is that as long as we maintain the same lifestyle and no drastic changes are made, even though we may think that what we do is enough, it is actually just an effort to relieve ourselves, while we are heading towards an environmental catastrophe.

Hello world!

Welcome to aboutecology. This is my very first post. My name is Nikos and I live in Thessaloniki, Greece. Thessaloniki is the second most populated city in Greece, with a population a bit over 1.1 million.
I am currently a student in two different fields, business and engineering. My major in business is Business Management and my minor is Computer Science. In engineering, I study Survey Engineering, focusing on Road and Traffic Engineering. This is the 6th year of my studies and it will, hopefully, be the last.
Although it may seem like my studies are quite irrelevant to ecologic issues, they are not. The rising concerns about environmental issues have affected almost all sciences, especially engineering, the field in which I plan to continue my studies. In particular, the field I am interested in is Renewable Energy Sources and I created this blog in order to discuss several issues about Renewable Energy Sources in Greece.
Around the city I live in, there are quite a few places of environmental significance, the most important of which are:

  1. The national park of Mount Olympus, which is the highest mountain in Greece and the house of the Twelve Gods of ancient Greek mythology. Information can be found on
  2. The national marine park of Allonisos, which is the largest marine protected area in Europe. Information on 
  3. The national park of Axios- Aliakmonas, which is an Important Bird Area. Information on

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The tragedy of the commons

The tragedy of the commons is a social dilemma first discussed by ecologist George Hardin in 1968. It discusses the fact that individuals tend to “act independently and rationally according to each one’s self interest despite the fact that they understand that depleting of a common resource is contrary to their long-term best interest”. (Wikipedia)

Although it is quite a shocking observation, there are a lot to discuss about this claim. To begin with, George Hardin assumes that individuals understand that acting irresponsibly is against their interest. However, in order to be so, individuals must have been educated accordingly. However, even in Greece, which is considered among the most developed countries of the planet, there is little, or no, education about ecological issues.

Moreover, there is the problem of analogy, meaning that individuals cannot understand that it is not just them acting irresponsibly, but there are also some millions more doing the exact same thing. Furthermore, individuals cannot understand the consequences of their actions, just because they have not witnessed them. And even if they have, they tend to forget as soon as they are tempted.

Finally the depletion of a resource occurs not only because of individuals acting irresponsibly, but also because individuals are too many to share that resource, no matter how responsibly they act.

The tragedy of the commons is not a recent phenomenon. People used to act irresponsibly towards their environment hundreds of years ago. The difference is that they did not have the means to cause irreversible damage to it. Unfortunately, we had such means before we could understand, let alone avoid, the damage we cause to our environment.

However now there is no excuse. We are aware of the dangers and we have the means not only not to harm our environment, but also to reverse the damage caused in the past. What we need is to differentiate ourselves from our predecessors and emphatically give an answer to this humiliating dilemma.