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The human population on Earth is reaching unprecedented numbers. In July 1999 the world population reached 6 billion (1). In fact, “there has been more growth in population since 1950 than during the 4 million preceding years since our early ancestors first stood upright.”(2) And we are far from stabilization as there will have been more children born in the 1990s than ever before. It took until 1930 for the world’s population to reach 2 billion; in just the last decade of the 20th century an additional 1.5 billion children were born (3).

Historically, the world’s population rose very gradually through the centuries. About 2,000 years ago the population hovered around 300 million people, mildly fluctuating but not growing considerably. It took an additional 1600 years before the population doubled to 600 million, from where it climbed gradually until around 1900 when the population really started to take off. By 1950 there were 2.5 billion people on the planet, or 53% more people in just 50 years. From 1950 to 2000, humankind will have grown 140% to over 6 billion.

It is important to note that counting the approximate number of people living in the world is difficult and often inaccurate. For example, the United States Census Bureau missed over 5 million people in its 1990 count. That’s “enough to fill Chicago twice over.”(4) You can imagine how difficult it would be to get a precise count in countries that are not as developed as the U.S. No accurate census has ever been taken in some parts of Africa. It is important to consider statistics from several sources in order to get a feel for the range of possible estimates.

Current World Population Estimates
6-8-995,991,389,311( 6 )
6-8-995,991,390,550( 7 )
7-1-995,996,215,340( 7 )
10-12-996 billion ( 1 )

Note: Many sources have borrowed information from other sites, so these statistics have been double-checked to make sure they do not overlap from the same original source.

Factors that Contribute to the Current and Future Population

Natural Increase

The number of people born minus the number of people who die in a given year represents the natural increase of population. In order to achieve a stable population, for every person that is born, one person must die. The world’s population today is far from stable, with many more people coming into the world than leaving. Even though some countries are averaging a replacement rate of 2 children per couple, their population may not be stabilizing because there are many more young couples having kids than there are aged couples passing away. This is compounded by the advancements of medicine and public health, which have lowered the incidence of infant mortality and famine-related death, and lengthened life expectancy in many regions.

The world averages about 23 births and 9 deaths per thousand people per year, a natural increase of 14 people per thousand per year (9). Another way of saying it is the world population adds 1.4 people per hundred per year, or an increase of 1.4%. This is the global average, however, as birth rates and death rates vary widely from country to country. While Middle Africa has a birth rate of almost 45 per thousand, Eastern and Southern Europe have birth rates of 10 per thousand.

*When calculating a specific country’s natural increase, additions or subtractions due to immigration are not included.


Immigration to cities or across international borders is spurred by many factors. Environmental degradation due to population growth is one motivation to migrate. With too many people living in one area, food and water shortages may become a frequent concern, or “human-induced climate change” may alter the region to the point that it is no longer a desirable place to live (12). Political unrest is another reason that people migrate.

Unemployment is one of the main reasons for immigration. In regions that lack economic opportunity people often seek employment in other countries where they perceive good jobs are plentiful. Today there are over 1 billion unemployed or underemployed people in the world. Considering that “the global economy must generate at least 40 million additional jobs each year to keep pace with population growth,” the future job market may cause unprecedented levels of immigration toward the more developed economies.

Growth Rate

Natural increase combined with immigration equals the total population growth rate of a region. The current global growth rate is about 1.33%, which is about 215,000 new mouths to feed every 24 hours. Considering that in the 1960s it was about 2.04%, our rate of growth has actually been falling in the last few decades. Most of the future population growth is projected to happen outside of the industrialized nations. In fact, “by 2025, 84 percent of the world’s population will live in developing countries.”(13) By 2050 the population of the more developed countries will be two percent less than in 1998, while the less developed regions will show a 64 percent increase, the fastest growth happening in Africa . ” Africa ‘s share in the world population growth will increase from the current 22 percent to 55 percent in 2045-2050.” Today, “Africa has the highest average population growth rate among various world regions,” at 2.8%, while Europe has the lowest, at 0.2% (14).

Global Growth Rates (3)

2045-2050*0.87%    0.34%   -0.23%

*rates for high, medium, and low projections

All in all, 10 countries account for 60% of the world’s population growth; China contributes 15% and India a whopping 21%. Currently 2 out of 5 people in the world live in either China or India.

Top Ten Countries Responsible for Global Population Growth, 1995-2000(3)

United States3%

In general, when socioeconomic status improves, the growth rate declines, but deaths due to hunger, casualties from regional conflicts, as well as disease and lethal viruses like AIDS can also make a big impact.

Fertility Rate

The fertility rate of women is one of the great unknowns when it comes to accurately predicting future population. So many factors affect a woman’s decision to reproduce, and those factors are likely to change at any time, especially in developing countries whose social systems can shift rapidly.

Cultural Factors that Influence Fertility (14)

  • Lineage continuation and expansion
  • More children = more “wealth” or assets/Old age economic security for parents
  • Help in agricultural work
  • Male-dominant decision making
  • Symbol of high male virility
  • Polygyny (the practice of having more than one wife)
  • Child Fosterage
  • Direct Factors that Influence Fertility (14)
  • Early marriage
  • Postpartum and peri-partum practices
  • Natural and pathological sterility
  • High infant mortality rates
  • High maternal mortality rates

“If fertility remained at current levels, the population would reach 296 billion in just 150 years. Even if it dropped to 2.5 children per woman and then stopped falling, the population would still reach 28 billion.” But future population projections are based on a worldwide reduction in fertility because as the fertility rates in many countries drop closer to the replacement level of 2 children per woman, the world is inching toward population stability. “During the last 25 years, the number of children per couple has fallen from 6.6 to 5.1 in Africa, from 5.1 to 2.6 in Asia, and from 5.0 to 2.7 in Latin America and the Caribbean.” The total fertility rate in the developing countries today is 3.1 children per woman, while in developed countries it is 1.6. In order to meet the middle population projection for 2050, the total world fertility rate must drop from the current 2.7 children per woman to 2.1 (11). Sixty-one countries, which comprise 44% of the world’s population, are already at or below replacement level, and 20 of them have been below it for more than 20 years.

There are many factors that can lower the fertility rates of women, both in developing and industrial countries. A basic education in general seems to be an important deterrent to marrying early and reproducing, especially if women complete secondary school. “In every society for which data are available, the more education women have, the fewer children they have.” For instance, in Peru, a woman with 10 years of schooling usually has 2-3 children, while a woman who has had no education has 7-8.

Knowledge of reproduction and contraceptive methods helps educated women make more informed decisions about their sexual activity and its resulting effect on their life. For example, “teenagers in many European countries are as sexually active as American teens, but their premarital pregnancy and abortion rates are much lower because they are more informed about contraception and use it more frequently.”(6) Such a lack of information or accessibility to contraception may explain why the U.S. has one of the highest rates of teen pregnancy of the industrialized countries; 60% of pregnancies and 40% of births in the United States are unintended (16).

Being self-supportive also helps women profit outside of the home or agricultural sector. “A woman with an independent income does not have to marry young or barter sex or childbearing for support.” In addition, her experience of economic freedom may reduce her drive for reproducing, whether because of the stimulation of independence and self-worth, the lack of need for more hands around the house, or the loss of adhesion to traditional cultural ways. Even if being self-supportive is out of the question for some women, studies have shown that women who are able to make household decisions “devote more income to maintaining better nutrition for their families, and are also more prone to set aside money for education and health care.” Empowering and educating women will make for fewer, healthier children, thereby slowing population growth.

Factors Related to Lower Fertility Rates

  • Basic rights: decision-making in the home, voting, owning land, having a job
  • Knowledge of reproduction and contraceptive methods
  • Access to contraception
  • Education/Literacy
  • Income independent of a man

Overall, high fertility rates and closely spaced births hinder the health and progress of people in many ways. Frequent childbirth generates more stress on women’s bodies and children receive less health care and education. The environment and other common property are more rapidly degraded, and there is less water and land for crops to go around with more people on the planet. With less nourishment, fewer health services, and little education, people are more likely to be locked into poverty due to high fertility.

Infant Mortality

As mentioned earlier developing countries have had the most impact on the world’s population growth. Because many of these countries are at the second stage of the demographic transition, death rates are declining while birth rates continue to rise. This decrease in death rates is mainly due to medicinal, nutritional, and hygienic improvements that have enabled infants to survive the rigors of early childhood.

In 1950 the infant mortality rate exceeded 15%. More than 15 children died for every 100 born, or another way to state it is that one died for every 6 or 7 born. By 1998 that rate had decreased to a little under 6%, which is a marked improvement meaning that for every 17or 18 children born, only one did not survive. 

Infant mortality is also linked to a country’s level of development since that usually affects their degree of health services. For comparison, for every 1,000 children born in Sierra Leone , 170 die, whereas for every 1,000 Japanese children born, 4 don’t make it. In other words 1 of 6 children born in Sierra Leone dies while only 1 of 250 born in Japan does not survive.

The United States ‘ infant mortality rate is 7 per 1,000. That’s 1 death for every 142 births. What’s interesting is that Japan and the United States are assumed to be on the same level of economic and social development, yet the U.S. infant mortality rate is double that in Japan . Obviously, a country’s level of development cannot be gauged solely by considering its infant mortality rate.

Life Expectancy

There is a close correlation between a society’s achievement of higher levels of economic development and the ability for its people to live longer, healthier lives. Better health and a longer life expectancy also means lower birth rates. As infant mortality rates decline due to better living conditions, people have fewer children because of the increased likelihood that nearly all will survive.

One indicator of an aging population is the median age of people. If you were to line up all 5.9 billion people in the world from youngest to oldest, the age of the person standing in the middle would represent the median age. The median age has gotten older through time since the population as a whole has aged. In 1950 the median age was 23.5 and by 1998 had only risen to 26.1. But in 2050 the population will have aged dramatically to a median of 37.8 years.

HIV & AIDS and Other Diseases

In some regions the HIV virus has reversed the gains that life expectancy had made in the last few decades. Africa has been hit the hardest. Currently, there are 30 million HIV-positive people in the world. Africa is home to 26 million of those victims. One of every 5 adults in many African countries is expected to die in the next decade due to AIDS. The disease is taking its toll on “the young professionals in the prime of life the very agronomists, engineers, and teachers needed to develop the economy.” Botswana in particular has “the highest prevalence of HIV in the world,” where 1 of every 4 adults, or 25% of the population, is infected.

Life expectancy in Botswana has fallen from 61 years in 1990 to 44 years in 1998 and is expected to fall to 41 years in 2000-2005. Considering that life expectancy would have been greater than 67 years, that’s more than 26 years of life per person lost to the disease. The growth rate will have decreased from 2.9% in 1990 to 1.2% in 2000-2005. By 2025, Botswana ‘s population “may be 23 percent smaller than it would have been in the absence of AIDS.” But fertility remains high, so the population will probably still double from 1995-2050. Other African countries are also suffering heavily. As death rates climb in Zimbabwe due to AIDS, the country’s population is expected to stabilize by 2002, marking regression back to the first stage of the demographic transition.

Can We Sustain the Current and Future Population?

Now that we have defined some of the causes of our current and future population growth, can our natural resources sustain a population of about 8 to 12 billion by 2050?

Virtually every important issue we confront today is caused or multiplied by population growth. The global economy of the 1990s stalled recently, but the demands of sevenfold growth since 1950 is destroying the Earth’s ecosystem. Even modest growth for another 50 years “would likely lead to deterioration of the Earth’s natural systems to the point where the economy itself would begin to decline.”

Wealthy economically developed countries impact the environment and deplete the planet’s natural resources much more than under developed nations. While people in poorer countries consume little but have many children, citizens in industrial countries have fewer children but consume much more of the world’s resources. Affluent peoples consume more in order to maintain the comfortable lifestyles they are accustomed to. They also produce greater waste since they utilize “disposable items” manufactured from plastics, paper, and metal. Developing countries produce about 6 kilos of industrial waste per capita the average person in an industrial nation is responsible for up to 100 kilos of waste.

Although the fastest population growth is happening in Africa an American’s impact on the environment will be over 250 times greater than a Sub-Saharan African. With only one-twentieth of the world’s population, Americans consume 20% of its resources.

Consumption “Facts”

  • “No country at any level of affluence has announced or even seriously contemplated limits on consumption per person.”(2)
  • “By most calculations we have used more natural resources since 1955 than in all of human history to that time.”(4)
  • Humans use 50% of all of the solar energy captured by photosynthesis (3).
  • Today’s world food supply supplies 2,700 calories per person per day. Although that could feed the world, our distribution of that food neglects 20% of the population (9).
  • A head of iceberg lettuce has only 50 calories and is 95% water, but takes 400 calories of energy to grow and 1,800 calories to ship to the East Coast of the U.S. (4).
  • Producing 1 pound of wheat requires 25 gallons of water with modern Western farming techniques. Producing 1 pound of beef requires 5,214 gallons of water (16).
  • 56% of U.S. farmland is used to produce beef; 80% of corn and 95% go to feeding livestock in the U.S., while one-third of total world grain output is fed to livestock (16).
  • “The average individual daily consumption of water (in the U.S.) is 159 gallons, while more than half the world’s population lives on 25 gallons.”(16)
  • Commercial energy consumption: 1 person in the industrialized world = 10 people in the developing world (16).
  • Humans generate more than 1 million tons of hazardous waste every day (3).
  • The largest man-made structure in the world is The Great Wall of China. The second largest is the Staten Island garbage landfill in New York (3).
  • According to a 1996 report by Clinton ‘s Council on Sustainable Development, the efficiency of our resource use will have to increase more than 50% by 2050 in order to keep pace with population growth (4).
  • With only 5% of the world’s population, Americans consume 20% of all metals, 30% of all paper, and generate almost 75% of total global toxic waste (9).
  • Americans eat 200 billion more calories per day than necessary enough to feed 80 million people (16).
  • While millions of people around the world starve to death, Americans spend $30 billion a year on diet programs. One-third of the U.S. population is significantly overweight (9).
  • Americans waste 200,000 tons of edible food per day (16).
  • “Americans constitute 5% of the world’s population but consume 24% of the world’s energy. On average, one American consumes as much energy as 2 Japanese, 6 Mexicans, 13 Chinese, 31 Indians, 128 Bangladeshis, 307 Tanzanians, or 370 Ethiopians.”(16)
  • “Americans own roughly one-third of the world’s automobiles, drive about as many miles as the rest of the world combined, and are far and away the largest per capita producers of carbon dioxide.” (9)
  • The U.S. produces 22% of world’s total industrial carbon dioxide emissions (8).

Many countries are not prepared to deal with the strain on education, transportation, and energy due to an increasing population. Basic social services, food supply security, employment, and proper resource management are several key goals that may be difficult to meet since so many people already lack these important components of a healthy life.

  • 1.3 billion people live in absolute poverty
  • 840 million people are undernourished
  • 1.4 million people lack safe drinking water
  • 900 million people are illiterate

The countries in Africa, Asia, and Latin America that seem least prepared are already facing environmental degradation. Such “resource scarcities due to population pressures cause domestic and international migration, exacerbate ethnic tensions, and drive wars and civil unrest.” On the other hand, as many countries improve their conditions and complete the demographic transition, they will adopt consumption habits similar to the developed world. This could have a devastating effect on our global climate and natural resources. Increasing average food consumption, especially of meat, fish, eggs, and dairy (which require a lot of grain), means that by 2025 food production will have to double in order to keep up.

If everyone on the planet today adopted an American lifestyle, precious natural resources like conventional cheap oil would soon be exhausted. Geologists, environmentalists and biologists who warn that there are limits to the planet’s resource sustainability are labeled “Cassandras.” (Dictionary definition of Cassandra: “One who utters unheeded prophecies.”) Lester R. Brown, publisher, and president of World-Watch magazine, represents the Cassandra paradigm when he says that “in many parts of the world, forests, aquifers, pasture lands, and fisheries are being utilized faster than they can be replenished. Despite the green revolution, world grain carryover stocks, and therefore food security, remain at historical low levels. And despite half a century of unprecedented economic growth, nearly one quarter of the world’s people live in extreme poverty.”

Other studies also support this viewpoint. In 1993 Dr. Richard C. Duncan published an article that presents four theories that examine the relationship between population and energy use (17). A graph from 3 million BC to 3000 AD shows that we are currently living in a century-long Industrial Phase. This phase peaked in 1980, when energy use per person was at its highest, and is predicted to last only until 2030 due to declines in energy use per capita. (Increased population versus limited fuel production equal less energy per person.) The 1980 peak may have been “the crucial turning point in human history,” signaling the end of industrialization and the beginning of de-industrialization toward stability at a subsistence level. According to Dr. Duncan, as long as the energy use per person or the efficiency of retrieving that energy increases, culture will advance. But the more impact the retrieval of that energy makes on environmental, social, and political systems, the less our culture is able to progress.

The food supply provides more evidence that the general quality of life may be diminishing. Grain supplies are declining; corn, rice, and wheat yields have dropped 6% since 1984. Famine or floods jeopardize the limited grain stockpiled, which currently stands at two months’ supply.

“Pollyannas” disagree. “Pollyannas” claim that humans are inventive enough to figure out ways to deal with present and future problems. (Pollyanna is a character from a novel that saw the good in everything; much like Dr. Pangloss, from Voltaire’s famed 18th century work, “Candide.”) Lawrence Summers, former World Bank economist, believes “there are no limits to the carrying capacity of the Earth that are likely to bind at any time in the foreseeable future.” If shortages were to occur, such optimists believe that a solution or substitute will be devised. Julian Simon, an economist who died in 1998, thought the greater the population, the larger stock of knowledge and imagination from which to draw. He also erroneously believed that because prices of natural resources have been falling, they are in greater abundance today rather than increasing in scarcity.

The optimists doubt the pessimists because history is full of economists and scientists that have made “doomsday” predictions in the past the “crying wolf” syndrome. Eighteenth-century economist Thomas Malthus predicted that a point would be reached in which resources would not be able to keep up with the population expansion. Each advance in technology would be less productive than the last (the law of diminishing returns) and eventually no further increases would be possible. “The power of population,” Malthus proclaimed, “is indefinitely greater than the power in the earth to produce subsistence for man.” But because in the last 200 years we have seen significant increases in productivity and standards of living and decreases in the relative cost of resources such as food and minerals, many people now doubt Malthus’ logic.

It is hard to escape the nagging evidence that rapid population growth exacerbates many social problems. Some people warn that “no government, no academic expert, has the faintest idea of how to provide adequate food, housing, health care, education, and gainful employment to such exploding numbers of people, particularly as they crowd into megacities.” But others urge us to “lift our gaze from the frightening predictions we’ll see that economic life in the world has been getting better rather than worse.” As difficult as it is for individuals to choose a side and appropriately modify their everyday habits toward those goals, it is understandable how governments may be just as indecisive. Without a consensus on the issue, policymakers may feel that it can be ignored for now.

Note: The use of the labels “Cassandras” and “Pollyannas” is not meant to be offensive. It is simply the easiest and briefest way to convey their differing philosophies on the issues.

Effects of the Current and Future Population

Food Supply

The most pressing issue of population growth is food supply. Since 1984, global grain harvest per person has been declining. Although cropland has increased since 1950, population has grown 7 times faster. Between 2000 and 2050, it is estimated that cropland per person will drop from 0.3 acres to 0.2 acres. This is an average, as there are many countries that are self-supportive while others cannot feed their own citizens. These concerns raise many questions of future sustainability. Will we have enough productive cropland to grow an adequate amount of food? If so, will import systems be able to provide food to the countries that cannot grow enough of their own? Will those countries have enough money to pay for imported food?

In 1999 there are 82 countries that cannot grow enough food to feed their people, nor can they afford to buy it from another country. As the population increases in many developing countries their cropland per capita will shrink to unsustainable levels. Countries like Japan and Taiwan already import 70% of their grain, but they have the money to do so.

Food “Facts”

  • “In two or three decades, farmers might need to produce 50 percent more food than they do now, without increasing their use of land and water, just to keep up with population and economic growth.”(13)
  • “The U.S. annually paves over an area the size of Delaware (9). “Almost 40 percent of the Earth’s land surface has been converted to cropland and permanent pasture.”(9)
  • Desertification is claiming 29% of the earth’s total landmass (8).
  • We are currently over-harvesting all major world fisheries (9).
  • To feed an exploding population over the next 50 years Africa will need to increase its food production by 400%, Latin America by 80%, Asia by 68%, and North America by 30%. Europe won’t need to produce more since it has the lowest birth rates in the world (9).
  • The world loses about 4.5 tons of farmable soil per person every year (6).
  • “In 1830, there were 32 acres of land per living human being. Today there are fewer than 5 acres, including uninhabitable land.”(8)
  • Grain harvest per person rose 38% from 1950 to 1984, exceeding population growth. It declined 9% from 1984 to 1998, falling behind population growth (2).
  • Since 1950, grain area has increased by 19% and global population has increased 132% (2).
  • Ironically, as we try to feed more hungry mouths, the pesticides we use poison 25 million people and kill 20,000 people every year in less developed countries (16).
  • Hunger and malnutrition claim 6 million lives worldwide every year (2).
  • “Famine is no longer due to a global food shortage,” but to unequal global consumption and poor distribution (1).
  • Irrigation worldwide is only about 40% percent efficient more water is wasted than reaches the crops. Modern techniques could raise the efficiency 25-80% (9).
  • Globally, people only use a few hundred species of edible plants of the 50,000 discovered. Only 15 species account for 90% of world food energy intake. Two-thirds of the global population rely on wheat, rice, and maize for their staple food (9).
  • Rangeland for animal meat production covers twice the global area of cropland (2).


Forests are extremely endangered by population growth. Just about everything humans do in order to grow and cook food, build shelter, acquire power sources, and develop areas affects forests. Clearing land for agriculture in developing countries is the top cause of forest destruction, as food production must keep up with the growing numbers of mouths to feed. Tropical forests are being cut down at an estimated rate of 59,500 square miles the size of Florida every year for various reasons.

Forests provide many services for the environment. Frontier forests can store “more carbon than is likely to be released by fossil fuel burning and cement manufacture over the next 70 years or so.” But once the trees are cut down, they release into the atmosphere the carbon they stored. In fact, forest clearing accounts for 25% of the world’s carbon emissions. Forests are also a source of many medicines that we manufacture today, and there is no telling how many cures are being destroyed every day. Humans are trading biodiversity, food and medicinal sources, nutrient recycling, climate regulation, and watershed management for cropland, pasture, fuel, and urban development.

Forest “Facts”

  • Average forest area per person: 9,067 square meters (95 x 95 meters) (8)
  • 75% of population growth and 75% of deforestation have occurred in the 20th century (2).
  • Forests covered about 40% of the earth’s total land area earlier in the 20th century. That is down to 27% or 20% in developing regions that clear land for agriculture and fuel wood (9).
  • “Half of the planet’s tropical forests have been destroyed or degraded.”(9)
  • For every acre of forest that is converted to farmland or pasture, another acre is left too degraded to maintain diverse ecosystems or produce food (13).
  • Every minute 50 acres of rain forest are destroyed (8).
  • “One production run of the Sunday New York Times requires product from 75,000 trees.”(3)
  • North America, Europe, and Japan comprise 19% of the global population but consume almost 50% of the world’s industrial wood and 63% of its paper and paperboard (2).
  • The world is producing 25% more forest products than is estimated for sustainable consumption (2).
  • About 97% of population growth will occur in developing countries, where most large-scale deforestation of temperate and tropical forests occurs. The most affluent countries are responsible for destroying boreal forests for paper and wood (9).
  • 75% of the world’s tropical forests will be harvested by 2025 (3).

Water Quality and Supply

Intensive farming practices and deforestation cause siltation of streams and rivers. Urbanization creates industrial and residential run-off, contaminating water supplies. Between water pollution, rising affluence from socioeconomic development and a rapidly growing population, an insufficient supply of clean water threatens many regions.

Water “Facts”

  • Globally, 70% of the water supply is used for irrigation, 20% for industry, and 10% for residential purposes (2).
  • Water shortages plague 80 countries, 12 of which have a severe lack (9).
  • Groundwater levels in northern China are dropping up to 1 meter per year (9).
  • The primary cause of water pollution is run-off from farmland, city streets, parking lots, and lawns (8).
  • “Waterborne infections such as cholera and other diarrhea-type diseases account for 90 percent of all infectious diseases in developing countries ? and 40 percent of all deaths in some nations” (2).
  • The water needed to supply world agriculture by 2025 will be the equivalent to the annual flow of 24 Nile Rivers (2).
  • Industry will use twice as much water as it does today by 2025 (11).
  • “One billion people will be living in countries facing absolute water scarcity by 2025.”(2)

Species Diversity

No matter how humans interact with their environment, there is a clear correlation between population and species loss. The more people, the less wildlife. Paul Harrison studied 50 countries and concluded the following:

Population per Square KilometerOriginal Wildlife Habitat Remaining
294 people or less59%
379 people or less45%
454 people or less33%

Biodiversity “Facts:”

  • Species loss today is 100 to 1,000 times the natural rate (2).
  • Half of all species in the world live in the watersheds of tropical forests (9).
  • About 4,000 species are lost every year in tropical regions (3).
  • An estimated 27,000 plant and animal species worldwide vanish each year three animals, plants, insects, or microorganisms per hour (9).
  • It is estimated that an average of only 0.1% of the pesticides used on crops reaches pests; 99.9% of the pesticides poison the ecosystem (16).


The population will be increasingly more urban in the 21st century. It is estimated that half of the global population will be living in cities, in numbers exceeding the current world population. Urban sprawl has already taken a toll on the environment. It has been calculated that 50% of wetlands, 90% of northwestern old growth forests, and 99% of tall grass prairie in the United States have been lost in the last 200 years due to development.

Urban “Facts”

  • 1 of 10 people lived in the city in 1900 and 1 in 2 people lived in the city in 1994 (1).
  • Of cities, Manhattan, New York, has 68,000 people per square mile, and parts of Cairo ‘s older districts have 160,000 people per square mile (15).
  • Employment opportunities in Africa are dismal, where 40% of people live in absolute poverty (2).
  • Europe averages 19 square yards of green space per person whereas Cairo has an average of 7 square inches (15).
  • Half of the global population (3 billion) has no access to sanitation. Almost half (2.7 billion) has no reliable source of safe drinking water (2).
  • By the middle to end of the coming century, 70% of the human population will live on only 2% of the world’s surface – in cities (15).
  • “The combined population of the ten largest cities at the end of the century 163 million will equal that of the twenty-six smallest countries.”(15)
  • In 2000, there will be 3 billion people living in cities, 4 billion by 2025 (9).
  • Housing demand will double by 2050 due to population growth and a shift to fewer people per household (2).
  • It is estimated that by 2050, global population will have increased 47% while the urban population will increase 114% (2).


While the U.S. enjoys its longest peacetime prosperity in history, 16% of the world’s population lacks clean water, sanitation, health care, and education. One in five people live on less than a dollar per day. By year 2000 it is estimated that over 75% of urban families living in developing countries will be impoverished. The “Pollyannas” are adamant that humans will overcome future problems, but a growing proportion of impoverished people lack good health, education, and other resources needed for survival. In effect, we may have a larger population with about the same “stock of imagination” as we had with a smaller population.

People “Facts”

  • It is estimated that “the richest 225 people in the world today control more wealth than the poorest 2.5 billion people. And that the three richest people in the world control more wealth than the poorest 48 nations.”(9)
  • “The poorest 10% of the world’s countries earn less than $130 per person per year,” or 35 cents a day (8).
  • In developing countries, about 3/5 of people don’t have access to sanitation, don’t have adequate housing, and 1/3 lack clean water (2).
  • Half the people in developing countries suffer from 1 of the 6 diseases linked to poor sanitation and water supply (2).
  • It is estimated that “every year one million children are forced into prostitution mostly girls in Asia.”(9)
  • Many women do not want larger families: of all pregnancies are purposely terminated worldwide. 150,000 abortions are performed daily, 1/3 of which are illegal.

U.S. Poverty Rates (9):

# of Children per FamilyFamilies in Poverty

Can We Slow Population Growth?

If population growth slowed the global environment would suffer less stress. Following through with the solutions that maintain sustainable population growth may simultaneously alleviate many of the problems that the population explosion exacerbates. Many people seem to agree that the following elements would make for a more equitable and sustainable world:

  • Strong national leadership with the priority of population stabilization through raising women’s status and speaking openly of reproduction.
  • Improved community health care and nutrition, especially for women.
  • Basic rights for women: reproductive autonomy, decision-making in the home, voting, owning land, opportunity to a job.
  • Protection of human rights.
  • Quick local access to family planning services and contraception sensitive to the needs of women.
  • Lengthening girls’ school enrollment/higher literacy rates.
  • Higher female participation in the labor force/employment opportunities away from the home.
  • Access to micro lending or credit, especially for women.
  • Conservation and protection of natural resources.
  • Policies and tax structures to protect or restore farmland from development.
  • Development of sustainable technologies and agriculture.

It has been said that “stopping population growth is like stopping a speeding train: There is a long delay between putting on the brakes and coming to a full halt.” That means that the sooner the brakes are applied, the fewer problems humans will cause. Unfortunately, no one strategy will solve the myriad of interconnected issues. Lowering birth rates is not the only answer. Relinquishing meat from our diets isn’t either. But when it comes down to it, deciding how many children you will have does not require that you give up anything and it could have the biggest effect of all, especially in the future.


  • The U.S. spent half a trillion dollars in 1998: 50% went toward traditional defense; 6% was spent on education; health, the environment, and justice each received 5%, transportation less than 3%; economic development almost 2%; and agriculture and energy less than 1% each (9).
  • In Africa, 85% of women in rural communities produce 80% of the food, but because of female discrimination, less than 10% of the women own resources or land. “If given the same resources now available to men, women would be producing 10 to 15 percent more food and giving more of it to their families.”(15)
  • Women engaged in small enterprises in Asia and Latin America have been found to average fewer children (13).
  • In 30 years of U.S. support of family planning services, 10 times as many couples in developing countries are using contraception and the average number of children per woman has gone from 6 to less than 4 (13).
  • By 1994, 60% of people in developing countries had easy access to some form of modern contraception (15).

The values used to calculate natural increase are also used to figure out what stage a country has reached in the demographic transition. The demographic transition is a 3-stage identification tool that indicates socioeconomic progress in comparison to the birth and death rates of a country. High birth rates and high death rates characterize the first stage. High birth rates but declining death rates mark the second stage.

Declining birth rates and stabilizing death rates characterize the third stage, marking a complete transition to population stabilization. Many industrialized countries, such as Australia, Japan, the United States, and some European countries are at stage three. Meanwhile, most of the increase in world population can be attributed to the developing countries.