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How much human life can planet Earth sustain?
Posted on Sat Sep 23 2006
How much human life can planet Earth sustain? It's a question scientists have been struggling with for hundreds of years. They have yet to agree on an answer. Thomas Malthus kicked off the debate in the early nineteenth century when he predicted imminent doom for the human race. He believed that the population of the earth was increasing at a geometric rate, while food production was increasing only at an arithmetic rate. Human population would soon outstrip their own ability to produce food, and there would be a catastrophe by the mid-nineteenth century. We're still here, so that obviously didn't happen. Technology allowed humans to produce far more food than Malthus anticipated. Even though Malthus was wrong, his ideas remain influential. The carrying capacity of the earth is a hotly contested subject. Many believe that we are at or near our capacity already. Others believe the earth can support far more people. It's far too complicated to truly determine what the real limit is. And even if we could, the "real" limit would be meaningless without proper context. The main context is lifestyle. Our planet can support many more people if we are living in near-starvation mode and consuming as little energy as possible, than if we are all living at North American levels of consumption. Practical considerations also matter. If we were all living in starvation mode, would we be able to survive, or would we be at war with one another, killing each other off so we can eat more food? Distribution of resources has always been unequal, and continues to be an issue now and in the future. Ignoring these considerations, can we reach some sort of estimate? Important factors that determine how many people the earth can sustain include food, drinking water, and energy. Let's look at each of these areas in more detail. Food The earth currently produces 2,264 million metric tons of cereals, which is the staple food of the world. If each person consumes 2,000 calories per day, 2,264 million metric tons of cereal will support a little bit over 10 billion people. Currently, around half of all arable land in the world is producing crops. If we clear-cut all the forests and jungles, we could double our theoretical food production. These calculations assume all we eat is cereal though. Most people want to eat more than just rice, bread and pasta. Vegetables and fruits are also produced on arable land. Most of this produces a higher calorie per area yield than cereals. But what about meat? Currently about one third of cereals produced in the world go towards feeding animals for meat production. Meat production is very inefficient in terms of land use. The more meat is eaten, the less people the land can support. Water It's hard to say much about water other than that we are in dire need. There are 1,385 cubic kilometers on earth. Most of this water is salt water, and not suitable for human consumption. Most of the fresh water available...is locked inside polar ice caps. Only 0.26% of all water is available for human consumption. Most of this water is in clouds or in the ground though. Only 0.014% of water on the earth is actually available for drinking. Problem? Yes! There are already severe water shortages in Africa and parts of Asia. North Americans use 1,280 cubic meters of water annually. Africans use 186. If there isn't enough water, such as is the case in many countries, disease and malnutrition are the result. This is already happening, and will continue to spread as population continues to increase. Water also affects food in a big way, as 70% of water used by humans irrigates crops. Energy This is another area where humans are already using up our resources. Right now, a large part of our energy comes from fossil fuels. Fossil fuels are a finite resource. Arguments abound over when they will run out. Some say that oil production has already peaked and is decreasing. Once oil runs out, natural gas and coal may also quickly be depleted as replacements for oil, and we will be left with nothing. In energy, it's not a question of how much life can be sustained. It's a question of when the life support will end. All of the above areas are subject to one major factor: technology. Throughout human history, technology has profoundly affected agriculture. Crop yields of today are far beyond what the first farmers would have dreamed of. Water technology, if it can unlock the secret of cheap and efficient desalinization, will provide an almost unlimited source of water. And finally energy. The energy that reaches the earth from the sun is enough to power anything imaginable. Attempts to harness that energy include solar panels, wind turbines and bio-diesel. Once a technological solution has been reached, energy will no longer be a problem. So how many people can earth support? Nobody knows. Potentially many more billions than are here currently. If we all become vegan, never bathe, and never drive, we'll be even better off. But if we continue as we are, we will be in trouble. Running out of energy will be a problem that we might not even get to, if we run out of water and the ability to grow food. Sources consulted http://www.pan-uk.org/pestnews/pn33/pn33p23.htm http://pages.prodigy.net/jhonig/bignum/qland2.html http://www.veg.ca http://www.lenntech.com/specific-questions-water-quantities.htm http://www.wikipedia.org CommentsLet us know what you think! |
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You would think by now that a way to change the oceans water into drinking water would've been figured out.
There has been. They have desalinization plants that are able to do this, but the cost in energy is enormous. So it makes it a last resort, but possible.
Thank you for such a comprehensive and enlightening article. The one point I would like to emphasize is how much of our cereal crops the and land is taken up with the production of meat. Not only do cattle use much of the land that could produce crops, but they also add the pollution of the water in their area. It seems unconscionable that the manufacture of meat continues in a world plagued by famine and water shortage.
Sometimes it comes to mind that people have a desire to keep each other from reaching their potential...If your current society has kept this from you... Welcome to the world...Economics is based off exploitation...people must not reach their potential for the majority to survive...ie life sucks...sorry for your middle class upbring
I don't know about you guys but the thought of cutting down the rest of the rain forests leaves me breathless.
So what is the answer? It is an exceptionally important question. I am amazed at how world leaders skirt around this issue. At an acceptable lifestyle, what is the maximum population the Earth can sustain. Perhaps it would be useful to to see the figures for a range of lifestyles. I do not have evidence to back up these assertions, but I imagine that there are already more people on Earth than can be sustained at the lifestyle of an average person from the USA or the UK. On the other hand, if you would like to live the lifestyle of a nomad in egypt where there is plenty of empty space per person (unlike New York City), then similarly the Earth would already be overpopulated. So what is the happy medium? If you wish to live the lifestyle of a modest European, for example. Two adults, two children, a 3-bedroom house, one car, clean water for drinking and bathing, meat once a day, 5 fruit and veg a day, fish once a week and communal areas for recreation, then what would the maximum population be that the Earth could sustain? Give us a range to indicate uncertainty. It would probably be more than 100 million, but I strongly suspect that it would be less than the current ca 6 billion. So we have three options: 1) Accept the gross inequalities and work to maximise your own comfort, this would almost certainly entail ensuring that others have less so you can have more; 2) Decrease the expected standard of living, at the current population I suspect that this would mean accepting that you won't eat meat more than once or twice a month, fish once or twice a year, don't expect clean water, no cars, flats not houses, etc.; 3. Work to decrease the population to a sustainable level. Sooner or later we will address the issue of overpopulation, but the sooner we deal with it, the less painful the solution will be.
On the question of sustainability; it is not! Not without reversing exponential human population growth and resource consumption. If we don’t limit our population Nature will do it for us. It is said that man differs from other animals because of technology and self awareness. Many of us are aware enough to extrapolate what man kind will do to the planet and to itself through its relentless nature to grow it’s population exponentially as if there will never be any limits. The day man used up half the Earth’s fossil fuels, for which most of our economy, food supply, and population is utterly dependent; is the day man ran into such a limitation. And now it’s time to demonstrate that man is different in a new way; to intelligently control, self limit and reduce its own population to a level that can be sustained indefinitely at a high enough standard of living in order to have a meaningful future. Before someone brings it up; yes—this is like ‘playing God’. God is said to be observed in nature as the power of life and death; ultimately having the result of creating a stronger more sustainable species. And so for man to ‘best’ survive and prosper far into the future perhaps some of us will really need to become like gods.
How much human life can planet Earth sustain? If they live like the folks in India, many more than you think. If they live like the folks in China, more than that! If they live like the folks in North America, well, what can I say?
Well, as an American I take offense. I don't waste, not like other Americans. But I refuse to live like they do in India or China. What we need to do is educate the people of this world. Not just the privileged, but everyone. The people of the planet Earth need to work together and not against each other. If we work together we could solve anything!
Interesting article, and here we are two years later beginning to see the effects of overpopulation with our fuel and food sources waining. Mike's opinion regarding the exploitation of many in the population being necessary to sustain our standard of living is proving true, as the rise of industry in China is resulting in higher fuel demand and increased green house gases. Clearly the technology is available to allow us to live much more efficiently ( it has been available for a long time), but whether or not we choose to avail ourselves of it, and how quickly, will be the test. The established energy providers maintain a firm grip on our economy, one that will not be broken without a fight. I believe we are entering a transition period, one that will be painful for many. In the end, I must have faith in humanity to come out on top of this struggle. Or at the very least, we will be cresting the top of our 'j-curve' and leveling out to sustainable levels.
This article is stupid. Its selfish and centered only around the idea that humans are the only ones that exist on earth. Clear cut the rain forest? WOW what an ignorant statement to make, its funny that the writer thinks the world will be able to sustain itself without these things. You need you oxygen dont you? last time i checked rainforest have been a source of many pharmaceutical drugs that have save many people. Its article like this that give people the weapons to be ignorant and think that we can keep going that way we are now and earths eco system wont pay the price.