Timothy Wilken
If the human population continued growing at the rate seen in 1990, the world would tally 694 billion people by the year 2150, the United Nations predicts. But that’s not likely, says Joel E. Cohen, Ph.D., professor and head of the Laboratory of Populations at The Rockefeller University. By providing numbers, population projections help nations shape social and economic policies. In the coming half century, Cohen notes, people are likely to confront difficult trade-offs between population size, economic well-being, environmental quality and cultural values. Cohen plans to discuss how Earth’s ability to sustain people–sometimes called its carrying capacity–on Friday, Feb. 9, at the annual meeting of the American Association for the Advancement of Science in Baltimore, Md.
“The clear message of the projections is that people cannot forever continue to have, on average, more children than are required to replace themselves,” Cohen says. “This statement is not an ideological slogan. It is a hard fact. For example, conventional agriculture cannot grow enough food for 694 billion people–not enough water falls from the skies. The finiteness of the Earth guarantees that a ceiling on human numbers exists.” (LINK)
Joseph George Caldwell writes in response to this morning’s question “What would a sustainable human population for the Earth once fossil fuels are gone?”
“I have researched this question is considerable detail, over a number of years, and reached the conclusion that it is on the order of about ten million people. It is interesting that this is (as I discovered recently) the same number that Sir Fred Hoyle suggested in his 1966 book, October the First Is Too Late. You can find my reasoning in Chapter X (“What Size Should the Human Population Be”) of my book, Can America Survive?“
Terrell Larson
How and at what level will the world population stabilise?
It can stabilise at a level sustainable by an animal driven (IE horse power) agrarian economy. It can stabilise at a higher technological level providing energy resources are available… perhaps through solar (and this might include space based solar) . It can stabilise at a level supported by nuclear.
If we colonise mars.. perhaps several decades down the track it can stabilise at a new level – a multiplanet level.
But any way you look at it – the population must stabilise.
Consider Easter Island. They stabilized at a level supported by fishing until they chopped all the trees down and then they re-stabilised at a lower level that did not include boats. So… what of our world? Where will we stabilise?
Personally, I’m optimistic. There are 100’s of years of energy resources readily available. Technology is moving forward very quickly.
Some in our group are working on converting wood to petrol. It looks like they are making excellent progress. I did a search via google on CO2 fixation – that was really interesting. Apparently there are algaes that fix CO2 about 10x the rate of forests. Apparently the usual energy capture efficiency of a plant is about 8%. I read that corn will increase production with CO2 levels bumped by about 1/3 while wheat can handle almost 3x.
If there are algaes that can scrub CO2 from the flue gases of power stations at several orders of magnitude improvement over typical forests… then we have the potential of a highly efficient solar energy capture system. Maybe we can even genetically engineer these bugs/plants to produce bio-diesel. There is a LOT of research underway in this area.
When we pass the Hubbert peak there will be a rude awakening… but there is a tremendous body of knowledge and technology ready to find its day in the sun – so to speak.
I agree there will be problems and it might be bumpy. But I’m not pessimistic. That is qualified. Some how the population has to be stabilised in a manner that is not enforced by mother nature.
Mother Nature is a pretty ruthless lady when it comes down to it. I think a lot of the discussion of energy and sustainability really revolves about the question of stabilizing the population… and stabilizing it in the 3rd world.
Do people agree? Tell me… other than through terrible diseases which we can do nothing about, such as HIV which IMHO (not politically correct) will de-populate africa and huge parts of Asia and India… how does the 3rd world control its population?
Ron Patterson
Terrell, I think you are missing the entire point. Sure, the population will stabilize at some point in the future, just as Easter Island did. But it is the collapse and undershoot of the population that will be the big disaster. When the population of Easter Island was collapsing, they fell into tribal warfare and cannibalism. The population then went way under what the island could support and what it does support today.
The current population of the world is way over what it can support after cheap oil is gone. And you talk of converting wood to petrol! I never heard of anything so absurd. Sure, we could probably do it but why? When fuel gets low, wood will be cut down for fuel and burned directly. Wood will disappear just like it did on Easter Island and in the Horn of Africa. It will disappear because people will need it for cooking food and keeping warm. And you wish to use it to keep automobiles running!
Even if we go nuclear all the way, that still does not solve the problem. Scenarios to convert electricity to hydrogen, then to fuel cells for tractors, trains, ships and all other transportation, are all, at least right now, pipe dreams. Such a total conversion would take decades and even then, the fuel would be enormously expensive. It will not solve the problem.
And even if it eventually did, the largest problem still looms. That is, the huge third world hungry population. When ìThe Limits of Growth” was written in 1970, the rich (us) verses the poor was 35 to 65. It is now 20 to 80 and the gap is still widening. We are about to be run over by starving hoards. We are ìThe Camp of the Saints” and the poor are growing in numbers as they grow in discontent. They are coming. They want their share of the wealth, their share of the ever dwindling energy pie.
Concerning your comment: “If we colonise mars.. perhaps several decades down the track it can stabilise at a new level – a multiplanet level.”
This is one of those ìsilly future world science fiction scenarios” that I swore I would never comment on again, so I won´t.
Arthur Noll
Where will the human population stabilize?
It will stabilize at a sustainable level. It will stabilize when we look at a lot of trees, and say, we must have 50 trees of various ages growing for each one we cut down in a year. Other things kill trees, so it must actually be more than that. If we want to cut down a thousand year old tree, we need more than a thousand growing.
We must look at soil and say, if we plow this land, we lose this much of the fertility, and figure if we can replace it from sustainable sources. Nutrients are constantly flowing downstream, we want to live within the bounds of what comes back up against gravity, the gifts of the birds flying inland, herds of animals migrating, fish swimming upstream to spawn.
If the mountains slowly eroding give us a gift of fertile sediments, that is something to count on for a very long time. If we cannot replace fertility on a piece of land within sustainable limits, we will not plow it, but leave it in perennial cover, and let it be grazed or browsed so that cover is not killed or compromised.
Whatever comes off, we will be sure that it does not go further than we can bring back with sustainable use of energy. We will stabilize when we do not see what is out there in terms of turning it into money, but in terms of sustainable harvest, and in terms of a sustainable harvest for other organisms as well.
I remember a man saying to me, those poplar trees (actually aspen) are just weed trees, but you can get so many dollars a cord for them as pulp. And I said, those aspens support the grouse in the winter, which support the goshawks, which also keep a check on the mice. They are a favored browse of the deer and rabbits and beaver, all useful animals to take a sustainable number of. They have a light wood that burns fast and hot, nice for cooking in the summer, sometimes you can make something useful out of the wood. When longer lived trees die or are cut, they are apt to come in first and grow quickly, holding the soil.
I would not cut them all out of here like weeds, and turn them into money, and paper for junk mail. Holding the line like this today is like holding your finger in the dike, and big holes opening up all around you. But we will not stabilize until we start to do this sort of math, and leave out the counting of money.
I see people having babies, and they have not figured where the food comes from to feed the child as it grows, or to house it when it gets older. They have not thought about it at all. Food to them comes from supermarkets, always full to the brim, and their pockets are full of money to buy it, and what else is there to think of? The lumberyard is full of wood to build more houses. We will stabilize when people think not of the money they have and the sex or babies they want, but of how many the land will support.
It will not matter what the technology is, these things come first, and they will dictate the technology. Not the other way around. Or we won’t be stable.
Special thanks to the EnergyResources Yahoo Group.
What is the Sustainable Human Population for Earth?
Brian Moscatello
Tenafly, NJ
Richard Lawrence asks, “What would a sustainable human population be for the Earth once fossil fuels are gone? 500 million? 2 billion?”
I haven’t a short answer. To see how complex the issue is, read “How Many People Can the Earth Support?” by Joel Cohen (1995). He doesn’t answer, exactly, but shows well the difficulty of the issue: at what level of affluence/consumption? How many calories per capita per day? Sustainable for how long – 100 years, 300, 10,000?
Cohen does allude (it takes a careful reading, since it is not highlighted), to the topic of this group – that among the many variables, oil/natural gas, water, topsoil, and other natural resources are finite, and that it is possible that population and resource constraints _might_ intersect (with most unpleasant results) before a transition to renewable energy sources and a stable population is effected.
Though an ideal text in demographics, Cohen’s book frustrates we who seek an answer now, “before it’s too late.” At the same time it is instructive (Everett Allie would likely approve of his scientific rigor) in the methodology we must employ to find the answers (as noted above, there’s more than one).
I think we see where Joel Cohen’s personal preferences lie in his ending quote from philosopher John Stuart Mill’s 1848 “Principles of Political Economy” when the world’s population was just over _one_ billion:
“The density of population necessary to enable mankind to obtain, in the greatest degree, all the advantages both of cooperation and of social intercourse, has, in all the most populous countries, been attained. A population may be too crowded, though all be amply supplied with food and raiment. It is not good for man to be kept perforce at all times in the presence of his species. A world in which solitude is extirpated, is a very poor ideal. (break) …, I sincerely hope, for the sake of posterity, that they will content to be stationary, long before necessity compels them to it.”