HUMAN POPULATION

Until the domestication of cattle (8000 BC), there were less than 10 million people on earth.

--Caesar's time, 250 million

--Columbus's time, 500 million

--early 1800s, 1 billion

--World population remained under 1 billion until the nature of disease was discovered.

--1923 2 billion

--1975 4 billion

--1994 5.6 billion

--2000 6.0 billion

While some countries are growing their populations slowly, many have more than doubled their populations since 1970.

--United Nations, 2005

--94 million babies are born each year; the world's population is increasing at 1.8% annually, at this rate the population will double in 40 years; 1/3 of the world's population is under 18

The world’s population increases by 23 people every 5 seconds.  This is a rate of increase of almost 400,000 a day and 145 million per year.  In 1998, the population increase was equivalent to adding another Germany to the planet.

--As of 2003, there are more than 6.2 billion people living on the planet.  By the year 2050, it is estimated that there will be 7.9 to 10.9 billion people.   Currently, about 1.2 billion people—almost ¼ of the world’s population live on less than $1/day and are very vulnerable to disease and environmental changes.

In the year 2000, the world's most populated countries were China (1.26 billion people), India (1 billion people), the United States (276 million people), Indonesia (212 million people), Brazil (170 million people), Pakistan (150 million people), Russia (145 million people), Bangladesh (128 million people), Japan (127 million people), and Nigeria (123 million people) (Raven, 2001). Seventy-five percent of the population in developed nations and 40% of the population in developing nations live in urban areas. Nineteen cities now have populations greater than 10 million (IPCC, Document III, 2007).

Almost a third of the word's population (31%) is under the age of 15. More than 120 countries may double their populations by the year 2050. Much of the reduction of fertility rates is due to the increases in education concerning contraceptives and their availability. In addition, one of the most critical factors determining fertility rates is the level of education for women. Ninety million girls in the world do not have the opportunity to attend primary school. In many underdeveloped countries, more than 95% of girls do not attend secondary school. Throughout the world, there is an observed trend of reduced population growth when the level of women's education rises. Even in the United States, the average number of children for women which are not high school graduates is higher than that for high school graduates which is higher than that for college graduates which is higher than that for women with a graduate or professional degree (Raven, 2001).
Much of the world's population is under the age of 15.

--United Nations, 2005

In the year 2005, the estimated world population reached 6.5 billion people. The percentage of the world’s populations which inhabits less developed countries is growing and is currently estimated at 5.3 billion. Almost 4 billion people live in Asia (United Nations, 2005).

Globally, the average person consumes 100 grams of meat per day, although there is considerable variation between richer and poorer populations.  (In developed nations, average meat consumption is 200 to 250 grams.)  Given the contributions of livestock to global warming, some have set a target of 90 grams of meat per day with only 50 grams coming from cattle (McMichael, 2007).

In 1950, the ten most populated countries on earth (in order) were China, India, the U.S., the Russian Federation, Japan, Indonesia, Germany, Brazil, the United Kingdom, Italy, and France. In the year 2005, the 11 most populated countries are China, India, the U.S., Indonesia, Brazil, Pakistan, the Russian Federation, Bangladesh, Nigeria, Japan, and Mexico. Given current rates of growth, it is estimated that the most populated counties in the year 2050 will be India, China, the U.S., Pakistan, Indonesia, Nigeria, Brazil, Bangladesh, Congo, Ethiopia, and Mexico (United Nations, 2005).

Currently, 1.8 billion people in the world are under the age of 15 (almost 1.1 billion of which live in Asia) (United Nations, 2005). Some countries have a median age of more than 40 (Japan, Italy, Germany, Finland, Switzerland, Belgium, Croatia, Austria, Bulgaria, and Slovenia) while others have a median age of under 16 ½ (Uganda, Niger, Mali, Guinea-Bissau, Burkina Faso, Dem. Republic of Congo, Malawi, Chad, Congo, and Liberia) (United Nations, 2005).

A family size of 2.1 children per woman is considered replacement-level fertility. A higher level will increase overall population size while a lower level will decrease population size (United Nations, 2005). Some countries have an average fertility of less than 1.3 children per woman ( Macao, Hong Kong, Ukraine, Czech Republic, Slovakia, Slovenia, Moldova, Bulgaria, Bealrus, Greece, Poland, and Latvia). In contrast, in other countries the total fertility can range between 6.7 and 7.9 (Dem. Republic of Congo, Angola, Liberia, Burundi, Mali, Uganda, Guinea-Bissau, Afghanistan, Timor-Leste, and Niger) (United Nations, 2005).

     How many people can the earth hold?  There are two factors which must be considered when determining the earth’s carrying capacity: the human population and the natural resources used per person.  It is true that some developing nations are straining the earth’s capacity by having large families, For example, the family size estimated to be the “replacement fertility” (the family size in which births will balance deaths) is 2.1 children.  There are dozens of African nations in which the average family size is more than 6.  Population growth rates vary in different parts of the world.  Developing countries tend to have the largest percentages of people in the youngest age groups; developed countries tend to have more even distributions.  As a result, population doubling times also vary: North America 93 years, Latin America 33 years, Europe 266 years, USSR 80 years, Africa 24 years, South Asia 37 years, and Australia 57 years.

      While the number of children is certainly a factor in determining the earth’s carrying capacity, it must be considered together with resource use.  Small families, especially in the United States, can strain the earth’s capacity much more than large families in poor nations by using an enormous amount of the earth’s natural resources per person.  The United States only composes 5% of the earth’s human populations, Americans use 25% of the earth’s energy, use 25% of the earth’s resources, and generate 19-30% of the earth’s garbage.  There is criticism directed towards many nations which spend a large percentage of their national product on their military.  The cost of two b-2 bombers is about equal to the amount of money needed to save the lives of 7 million poor children and provide a basic education to 90 million poor young women.

     How many people can the earth hold?  If all the people of the world adopted the American standard of living, there would already be far more people on earth than the planet could hold.

Americans have a far greater per capita income than most of the rest of the world.

from United Nations, 2005

The United States has far more cropland per person than many countries.

--from United Nations, 2005.

Americans consume far more calories per day than most people on the planet.

As populations grow, diseases such as AIDS can spread more easily.

At the end of 2005, an estimated 38.6 million people in the world were infected with HIV. In that year, 2.8 million died because of AIDS and 4.1 million people were newly infected. Although the rate of infection is declining from its 1990s peak in most areas, the total numbers of infected individuals will continue to grow because of population growth and the greater longevity of AIDS patients. Africa (particularly South Africa) continues to be the global epicenter of the epidemic. More than 2/3 of AIDS cases in Asia occur in India. In low and middle income countries, an estimated 1.4% of males and 3.8% of females are infected with HIV (UNAIDS, 2006). In 2005, $8.3 billion was spent on AIDS and the annual expenditure increased an average of $1.7 billion per year from 2001-4 (UNAIDS, 2006).

In the United States, an estimated 1.2 million people are infected with HIV. This is the highest number ever, due in part because of greater longevity of infected individuals and in part because the rate of new infections is comparable to that of the late 1990s (UNAIDS, 2006).

AIDS is more readily transmitted in the presence of other sexually transmitted diseases. An estimated 340 million people contract a sexually transmitted disease each year (UNAIDS, 2006).

--after Kemp, 2004

--after Kemp, 2004

AIDS is decimating the adult populations of many countries.

--28 children will be born this year, 2 of which will die in their first year

--330 (one third) of the village are children and have not yet begun to reproduce

--10 people will die this year (including those two children)

-- as a result, next year the village contains 1018 people