Saturday, October 10, 2009

population...again n again...




Population Quotes

Rev. William G. Sinkford, President, Unitarian Universalist Association

Unitarian Universalists believe that we are all part of the interdependent web of existence, and so our personal choices affect all of creation. Ours are the only hands on earth to do the work of salvation, and we cannot relinquish responsibility for the fate of our planet. Unchecked population growth is a threat to environmental sustainability, but it is also a threat to the economic health of communities, families, and individuals. Persons in the developed world have more rights and resources for making responsible reproductive choices, and we need to ensure that all people have the same freedoms.

Sir David Attenborough, author of The Life of Mammals.

Mankind is looking for food not just on this planet but on others. Perhaps the time has now come to put that process into reverse. Instead of controlling the environment for the benefit of the population, maybe we should control the population to ensure the survival of our environment.

Garrett Hardin, author of Exploring New Ethics for Survival.

For too long have we supposed that technology would solve the "population problem." It won't. I first became fully aware of this hard truth when I wrote my essay "The Tragedy of the commons," ... Never have I found anything so difficult to work into shape. I wrote at least seven significantly different versions before resting content with this one, ... . It was obvious that the internal resistance to what I found myself saying was terrific. As a scientist I wanted to find a scientific solution; but reason inexorably led me to conclude that the population problem could not possibly be solved without repudiating certain ethical beliefs and altering some of the political and economic arrangements of contemporary society.


Thursday, October 8, 2009

what is the demographic transition???want to know??let's check it out!

The Demographic Transition

This is the name given to the process that has occurred during the past century, leading to a stabilization of population growth in the more highly developed countries. The Demographic Transition is shown schematically in Figure 6. It is generally characterized as having four separate phases or stages.

Stage 1. In this early stage of the demographic transition in Europe, birth rates and death rates are both high. Modern medicine had not yet developed techniques to lengthen life substantially and standards of personal hygiene were comparatively low. Both rates fluctuated depending on circumstances.No demographic transition has occured.

Stage 2. In this stage, standards of hygiene and more modern medical techniques began to drive the death rate down, leading to a significant upward trend in population size. The birth rate remained high, as much of the economy was based on agriculture. Mexico is currently between this and the following stage.Stage 2 and 3 are indicative of a partial or first demographic transition.

Stage 3. Urbanization decreases the economic incentives for large families. The cost of supporting an urban family grew and parents were more actively discouraged from having large families. In response to these economic pressures, the birth rate started to drop, ultimately coming close to the death rate. In the meantime, however, the increased population in Europe led to tremendous societal pressures that caused large scale migration (e.g., to the USA) and extensive global colonialization.

Stage 4. The last stage of the demographic transition in Europe was characterized by a higher, but stable, population size. Birth and death rates were both relatively low and the standard of living became much higher than during the earlier periods. The developed world remains in the fourth stage of its demographic transition. A good example of a country in this stage is Sweden. At stage 4, we speak of countries having completed the second or a full demographic transition.

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Wednesday, October 7, 2009

Population Growth Over Human History

"Go Forth And Multiply!" That's what the human population has successfully been doing for thousands and thousands yeras, expanding, exploring, migrating, conquering, utilizing, evolving, civilizing, industrializing, and now, destroying the very land upon we live.

Past Human Population Growth

The human population growth of the last century has been truly phenomenal. It required only 40 years after 1950 for the population to double from 2.5 billion. This doubling time is less than the average human lifetime. The world population passed 6 billion just before the end of the 20th century. Present estimates are for the population to reach 8-12 billion before the end of the 21th century. Of the 6 billion people, about half live in poverty and at least one fifth are severely undernourished. The rest live out their lives in comparative comfort and health. the factors affecting global human population are very simple. They are fertility, mortality, initial population, and time. The current growth rate of ~1.3% per year is smaller tahn the peak which occured a few decades ago (~2.1% per year in 1965-1970), but since this rate acts on much larger population base, the absolute number of new people per year (~90 million) is at an all time high. The stabilization of population will require a reduction in fertility globally. In the most optimistic view, this will take some time.


The current growth of population is driven by fertility. The more developed countries have lower fertility rates than the less developed countries. The fertility rates in the developed world are close to replacement levels, while the rates in the developing world are much higher. Thus, population growth and levels of developement are clearly linked. Fertility is largely controlled by economics and by human aspirations. the high fertility of the developing world can be partially explained by the large number of hands needed to perform low-technology agricultural tasks. In these areas, families with large numbers of children realize that having more children decreases rather than increases their standard of living. A dramatic example of this effect occured in Thailand, where, as soon as parents realized that future economic status was linked to the secondary schooling, which is expensive in Thailand, the fertility rate dropped from about 6 to 2 in a decade!


Mortality, or the death rate per individual, is another determining factor of population growth. In the developing world, the death rate has dropped, more or less continously, since the start of the industrial revolution. The combination of decreasing death rate to the narch of progress in sanitation and medicine, coupled with the decrease in birth rate due to changes in the economies, has led to a profound change in the population growth curve in the developed world. This changes is called the Demographic Transition.

Future Global Population Growth

Anyone who examines world population over the past two centuries certainly must be astounded, and quite possibly alarmed. The global population reached one billion in 1804. in 1927, some 123 years later, it passed two billion. sixty years later, in 1987, the world population was five billion, and 12 years later, in October 1999, it is estimated to have passed six billion. small wonder that many are concerned about this bodes for our future. due to the momentum represented by steeply pyramidal age distribution, population growth surely will continue for one to several generations. Most of that growth will occur in developing nations. an eventual world population of 8-12 billion is expected by the end of the century. but estimates change frequently. According to a report from the United Nations Population Fund, based on 1998 analyses, projections for the future global population are being revised downward. the projection for 2050 now is 8.9 billion, substantially lower than the 1996 projection of 9.4 billion.


Tuesday, October 6, 2009

human population crisis


If you were to take a standard sheet of writing paper 0.1mm thick and cut it into two sheets, placing one a top the other, it would then be 0.22mm thick. Then, cutting the stack of two and making a stack of 4 sheets, it would then be 0.4mm thick.

Do you believe that, if you continued to do this just one hundred times, doubling the size of the stack each time, the thickness of the stack would be 1.334 x 1011 light-years???

Actually, that is an example of exponential growth, where the rate of growth is always proportional to its present size. Exponential growth also applies to the human population. It begins growing very slowly, but over generations the growth rate increases more and more rapidly, similar to a snowball affect. It took the human population thousands of years to reach 1 billion in 1804.

However, it took only 123 years for us to double to 2 billion in 1927. The population hit 4 billion in 1974 (only 47 years), and if we continue at our current rate, the human population will reach 8 billion in 2028. Doubling from our present count of 6.8 billion to 13.6 billion will have a much greater impact than our last couple doublings combined.

Overpopulation is not population density (amount of people per landmass), but rather when the number of people in an area exceeds the resources and the capacity of the environment necessary to sustain human activities. So much focus is placed on the rapid population growth in third world countries.

However, when we compare lifestyles of the rich countries vs. the poor countries, the rich countries are a much greater problem. Just as much as the population size, we need to consider the resources consumed by each person, and the damage done by technologies used to supply them.

Overpopulation is when the number of people can not be permanently maintained without depleting resources and without degrading the environment and the people’s standard of living. Because we are rapidly using up resources around the world, virtually all nations are overpopulated. This applies even more so to the rich nations. As we use up the resources, the earth’s carrying capacity continues to decrease.

Just like with people, an overpopulation of animals is not defined by the number of animals that could hypothetically fit within a specific area, but rather when the number of animals that occupy their habitat are not capable of behaving as they naturally would. Unfortunately, the animals; behavior is often altered not so much by their number, but by humans encroaching upon their habitat and then claiming the animal to be a nuisance to man. We should practice the saying “live and let live,” but we do not have the resources to do this while our number continues to increase.