If humanity has one characteristic which has shaped the Earth's environment it is a capacity for constant expansion. Throughout history, population levels have increased exponentially, bringing ever greater demands on the natural world.
This process is not about to stop.
According to estimates from the United Nations Population Division, by the middle of this century the number of people will increase by another 40 percent, from a current 6.5 billion to 9.1 billion.
Yet at the same time, perhaps curiously, some countries will face an entirely different crisis as falling birth rates and an ageing population create too many retirees with not enough workers to support them.
This is because the population increase, however massive, will not be evenly distributed - no less than 95 percent of it will take place in poorer nations, the UN predicts. In contrast, populations in richer countries will remain more or less stable or even decline.
The main impact will be felt in Asia and Africa. For example, by 2050 India will have to find land, housing and energy for a predicted half a billion more people than now, by which time it will have overtaken China as the globe's most populous nation.
Over the same period, according to UN estimates, the populations of Nigeria and Ethiopia will more than double, with that of the Democratic Republic of Congo and a series of other African nations rising three-fold.
And while the United States is likely to see a migration-led population increase of around 40%, leaving it with more than 400 million inhabitants by mid-century, 50 or so other nations, including Germany, Italy, Japan and much of the former Soviet Union, are expected to see numbers drop.
This brings its own troubles, not least a looming pensions crisis as governments try and calculate how a smaller working population can pay for the upkeep of massively increased numbers of the elderly.
Global average life expectancy at birth has shot up from 47 years in 1950 to 65 years now. By the middle of this century, a third of the people in richer nations will be aged 60 or over.
The longer term is harder to predict, although the United Nations says that if current trends continue, the global population will begin stabilizing later this century.
According to a 2004 report which tries to estimate populations to 2300 by extrapolating current trends, the world figure will peak at just over 9.2 billion in 2075, and by 2300 will have slipped back marginally to 8.97 billion.
Environmentalists agree that over-population has an impact, but stress this it is more complicated than it first appears.
"Obviously, human numbers is an issue in terms of environmental impact, but it's not so simple," says Tony Juniper, director of Friends of the Earth.
"If you look at the impact of an average US citizen compared with the impact of an average citizen of Mozambique, it's hundreds of times more in terms of materials and energy being used.
"Simply drawing a direct relationship between the number of people and the environmental impact is not right."
Is the world over-populated? What measures should be taken?
Synthetic gas and clean coal must be done now. We need diesel hybrid trucks and trains, and clean coal vs. We should not allow China to build a new dirty coal plant every week. Come on! Ocean wave energy will be a big part of the solution.
I think that to control population, first of all a well-balanced government should be in place. This government should try to distribute knowledge everywhere. This in turn would bring awareness and the problem of overpopulation can be solved.
The world population is the only threat to this planet and the future o four children. Global warming, pollution, these are all symptoms of over population. The leaders of the world must get together and spend billions of dollars on educating the masses on the importance of each of us having only 2 children, and the first not until age 30. This will peacefully reduce the world population by half in about 100 to 200 years.
In my opinion the world population has become out of control, and the main source of the problem comes from third world countries. America being one of the most powerful and richest nations in the world has the power to act on the situation. If we could bring better sexual education and birth control to these countries there might be a significant drop in population.
India is doing little to control the population, which is in fact the root cause of all its problems. The current government may be basking in the glory of economic growth, but do they realise we are only providing cheap labour? They also don't realise that this so called development cannot be sustained and it will only lead to serious health and environmental problems and also a rise in crime.
What is development if most of the population is below poverty line and a majority do not have access to basic health care, sanitation or water supply?
There should be greater allocation of resources for family planning projects and better incentives for smaller families. I think even the multi-national and private sector industries should give better perks for people who limit their families as I think even the educated in India are not in favor of family planning.
I think international organizations should also give greater emphasis to population control.
It is not only third world countries that are contributing to the crisis of over-population, in the UK there is an increasing number of teenage pregnancies. Wherever one lives, one should have a child because they are able to support it, not the other way around.
Education on Aids and how overpopulation affects everyone is key to solving the problem. In third world countries where the economic situation is bad, if one family has six children, only four might make it to adulthood.
L.K Vance suggests there should be a limit of six children. I struggle to take that in. Could they clarify that comment?
I firmly believe that this planet can only sustain a population of 3 to 4 billion. Any world population larger than that will eventually have dire consequences. People, no matter where they live or the nature of their economy, must consume natural resources.
With the population at almost twice what the Earth can sustain, we will eventually "use up" the gifts this planet offers and the quality of life for all will suffer.
The world is not overpopulated yet, but soon it will if birth control is not imposed. One kid per family is a must. Educating people in the Third World about the importance of birth control is a must. Perhaps we could provide incentives for those who have one kid per family. A minimum age to get married should be imposed to avoid very young people to get married.
Uneducated people should be taught about the Billings method of contraception. It is very simple and very effective. One just needs to get past the proud male syndrome.
In Third World countries where there is famine and uncertainty, birth control should be mandatory. People are having too many babies that they just can't care for. Maybe there should be a limit to six children per family in countries where parents can provide care for their children.
Just birth control -- one to two kids per family, or none to some cases! Or else we will spread like a virus and destroy what 's left on this Earth, and in the process ourselves.
Yes, the world is overpopulated. I believe we can prevent it if we help each other (the Third World and the First World countries).
It's obvious that the world is over-populated. Countries like Australia and Canada seem to function very well with small population densities, preserving their natural resources. My country could do very well with half its present population or less. I don't understand why some people think the Earth should be populated to saturation point, there seems to be no advantage in that, only disadvantages.
And if we don't control our population nature will, eventually, in a terrible way. I believe UN should establish, through our representatives, future population reduction goals for each country.
This should be done in a rational way, distributing population according to available space in countries and regions, preserving important natural resources, so as to reach the next century with a total stabilized population of 1 billion people in the whole Earth.
Mankind is a virus on this planet. A parasite that sucks the life out of all the world's resources and gives nothing in return. The population now is already far greater than this precious Earth can handle.
Human beings have become a fungus on the Earth, mindlessly spreading across the land, destroying everything they come in contact with, leaving nothing but unusable waste, poisoned waters and soil stripped of minerals and nutrients. It is only a matter of time before there is nothing left.
Each and every one of us should feel the shame of what we are continuing to do to this planet. Even if the population of the world were to somehow be halved, the children of our children will need land that is capable of providing crops, pasture and clean water. Do those children even have a chance? Can we give up our most basic luxuries? Cars, televisions, and all the other items of an industrial age that led us to this insane need for more and more oil resources?
I don't have all the answers, but I do know that for anyone to survive in the future, we must be willing to give up a great deal and begin living the simple lives of our ancestors. We need to become responsible for the small patch of earth that we inhabit. Yes, we should return to the horse and buggy, grow our own produce and raise our own goats, pigs and chickens.
But I don't have the slightest idea on how to bring this about. Most of us are unable to afford that acre of land that we would need to become self sufficient. Additionally, building codes prevent us from building our own shelter. In conclusion this world has to see some very great changes.
In Australia the government pays a child endowment to families as an incentive to have more children. Governments in all countries should be paying incentives to couples NOT to have children, or at least to limit the size of families to two children.
Quit worrying about it. We have a flu pandemic coming that will take care of any concerns about overpopulation.
The Earth is not at all overpopulated and it will never be. As said, it has the necessary resources to feed all; to meet the needs of all but not enough for the greed of a few.
Anyone who knows anything about environmental matters and the state of the world should realize how destructive our species is and how much our future is in jeopardy.
Every single person has a huge impact on the world. Everything is connected. Think of all the plastic diapers and *things* every baby goes through, all the plastic and paper we all consume, all the fuel that goes to transport our goods, all the heavy metals used in our electronics, all the fertilizer and water used to grow our food -- which we eat too much of...
Most children grow up to have their own car, their own house (and house size in the U.S. has been increasing), their own children... And the cycle continues.
We consume so much more than the Earth can sustain. QUALITY of life is so very, very important and we won't have it if we keep our heads in the sand and think that our reproductive choices don't affect EVERY SINGLE LIVING THING.
Yes, the *level* of consumption is very important, but even if per capita consumption goes down and population continues to go up, the problem won't change.
We need to increase education and the rights of women worldwide because that has the biggest link to family size. Women who have their own goals and dreams and value do not need to feel their role is only to take are of others. Women must know that their goals matter and are obtainable!
Government-funded vasectomies and more incentives to adopt should be widely available. Adoption is a great way to have a family without adding more people to the world.
My boyfriend will be getting a vasectomy and we will adopt if we choose to have a child. Every child deserves a loving family, and a child that shares a larger percentage of your genes is not inherently more valuable than one that has fewer of your genes! A child is a child is a child! Adopt!
Is the world over-populated? I think it is and always will be. Because I don't believe in abortion. It's a sin!!!!
Overpopulation, especially in industrialized countries like America, is at the root of both environmental and social problems. Overconsumption is a far greater detriment than people realize. The rate at which this country consumes is nothing short of gluttonous.
It is more than a question of space -- it is a question of resources, they are FINITE. People need to seriously question their lifestyles, their sense of entitlement. their reasoning for having large families and we need more education about birth control. Unfortunately these type of changes take generations to implement and I fear we do not have that amount of time.
I absolutely believe the world has gotten to be over-populated. Children are having children and people who can't afford to feed themselves are having children who they can't afford to feed.
They get on welfare, drive big cars, wear fancy jewelry, get their nails and hair done weekly but can't or won't work. Who pays for this? We do, the taxpayers. While I totally agree with welfare, I think it needs to be restructured to be available to those who need it and not for those who think they deserve it.
The problem is not with overpopulation, it is simply a case of unfair land distribution/resource distribution. Shackle that to the corrupt IMF/World Bank and therefore if you have nothing you will remain with nothing.
I think the best solution for overpopulation is to allow every family (woman-man, man-man, woman/woman) to have one child in total. This should reduce the world population by half over a period of time.
Don't blame me and my girlfriend for overpopulation. We have no kids and don't want any. I had a vasectomy 10 days ago. The procedure was quick, inexpensive and the post-operative discomfort was minimal.
To say that the world is overpopulated is an oversimplification. The trouble with population is that the problem is very complex and has no simple answer.
Technologies exist that could revolutionize subsistence farming and "green" commercial agriculture. The problem with those technologies is in their implementation.
The UN has done a great job of attempting to deploy large-scale agricultural programs that treat the Earth kindly while providing food and potable water to the donor community. The trouble lies in the vested interest of the people who live there. I have seen several great programs just "up and die" after the projects were left to the farmers. The community didn't understand the gravity of the program, nor how it worked, nor how to sustain or maintain it when the UN ran out of money and had to leave.
Fertility restrictions and similar government-mandated programs such as tax incentives would never work. We have seen the results in China and India, where male children are revered and girls are treated like so much trash to be taken out. Tax Incentives won't work in nations like Saudi Arabia, where there is no personal tax, and wont work in African Nations that have experienced 1,200% inflation in the last two years.
War and Famine will always be with us, but those are not "solutions" either. War and Famine are NOT "natural stopgaps". Neither is disease. More often than not, these events are triggered by human greed and carelessness. We need only look to the Horn of Africa to see that.
Here is the rub: Nations whose populations do not grow pay an economic price as their population ages. Many European nations are waking up to an aging population and realizing they don't have enough young people to do the necessary work to support the elderly.
Even the U.S. is "on the bubble" as we, too, realize that the immigrant population may be our best hope for a strong economy in the years to come. (Yes, that's true, ask any economist).
I am not surprised to see that so many of your readers are content to sit in front of their computer terminals and let the world sort out its own troubles. "Let them die" seems to be one half the consensus opinion. Still others think that suppressing peoples right to decide how large their family should be ought to take care of the problem.
What those two camps don't understand is this: 1) Those "quick fixes" have been tried and have failed miserably. 2) Government will not -- cannot -- work to affect a change in nations with weak or no enforcement or assistance.
So what do we do?
Invest. Invest our money, our time, and our effort into finding solutions. Each one of us who is willing to help should. We have to own the problem. Sitting back and watching African or South American or Asian or European kids starve to death on the TV news will not help a single soul on this earth. Volunteer. Look for ways to spend some time in the field. Looking face to face at a starving child is the best possible way to drive the point of ownership home. Live where they live for a while.
What should we not do?
Sit and stare. Criticize. Be Greedy and complacent if you must, it is your right. But sty out of the way of those are willing to help.
Population growth is going to be with us for a while, a long while. The problem is both economic and human. It is in the interest of every nation, indeed - everyone - on earth to help find a way out of the woods.
I see the population explosion contributing to global warming just from the fact that there are billions of people radiating 98 degree body temperatures into the atmosphere. I don't see this being addressed by anyone. That is a huge mass of people at a constant temp of 98 degrees. The energy we use to heat and cool this same populace is also a major contributor.
Yes, the world is overpopulated. The birth increases in poor countries and the migration of the poor to rich countries will exacerbate the use of materials and energies in rich countries. Overpopulation by the poor is a disaster for the Earth and its resources. Population control and worldwide birth control efforts must be put into effect immediately.
Great Web site.
They say hydrogen is the future of fuels since the only pollutant it produces is water vapor. If the majority of vehicles and factories used hydrogen, we will get other environmental problems that we have not yet discovered due to too much water vapor in the environment. Will hydrogen production/extraction cause pollution?
I believe that if people cannot be responsible themselves in limiting the amount of children that they have, then the government needs to step in.
There is absolutely no reason why a family should have more than two children. How many people do they think this planet can sustain? What about sterilization after two kids? Is that so wrong?
Until people can start taking care of this planet properly, child limits should be enforced. Respect the Earth because it is all we've got. The human race seems to be like a virus, growing and destroying everything in its wake. We need to find the cure.
Each woman bearing only one natural child, then submitting to sterilization, should be granted freedom from taxation for the balance of her lifetime.
The key to overpopulation, and probably many of the world's ills, lies in the empowerment of women. Women who can control their fertility, and who have basic social and economic rights, will control population growth, as they already do in most of the developed world.
The alternative is to let war, famine and pestilence do the job for us. Unfortunately the U.S. has become a virtual theocracy and no longer supports fertility control programs in Third World countries. In that way, too, we are part of the problem.