The planet we live on can obviously not support an infinite number of people. There is an upper limit on population size, though this is not a hard limit. It is possible for species to overshoot the carrying capacity of the Earth (or any individual ecosystem) by consuming resources at an unsustainable rate. By drawing down ecological capital, instead living off the returns of that capital, short term growth can be accomplished at the cost of reducing future carrying capacity, with generally disastrous results.
Carrying capacity is defined as follows:
The carrying capacity of a biological species in an environment is the population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment.
Like any other species, we are obviously limited by the amount of fresh water and food available to us. Unlike other species, though, we have the capability to modify our environment in ways that can increase or decrease supplies of these necessities. In some cases, we can make changes that will maximize short term supply at the expense of long term supply. Our technology and intelligence give us more flexibility than other species, though we are still subject to physical limits, like any other species, barring expansion beyond our planet.
Because of these differences, some past estimates of human population development have been inaccurate. Paul R. Ehrlich famously predicted a population crash, caused by mass starvation, in the seventies and eighties in his book The Population Bomb, published in 1968. He was unaware of the Green Revolution which was starting to take off during that period and would allow for great increases in agricultural productivity through the use of industrial farming methods and the widespread use of fertilizer.
Unfortunately, however, while the Green Revolution has indeed allowed us to produce much more food, which has also allowed for additional population growth, it is not sustainable. There are three main reasons for this. First of all, we are nearing the point of peak oil. This is the point at which oil production reaches its maximum, then begins to slowly decline in every subsequent year. This doesn't mean we will run out, but that there will be a smaller supply every year than the year before. This means increasing prices and the possibility of supply interruptions. Industrial farming methods and fertilizer are dependant on this oil, but it will not be available forever, at least not at prices that make these methods feasible.
The second reason is that while industrial agriculture produces abundant results in the short term, this is at the cost of depleting the soil over the long term, which can only be avoided using sustainable farming methods. Organic farming methods can produce stable production over the long term, in a sustainable way, but they cannot produce as much food. Nevertheless, the longer we maintain the industrial methods, the more arable land will be lost, and the more the limit of future sustainable food production will be reduced. We are producing more food now, at the expense of our ability to do so in the future.
The third issue is that of global warming. Rapidly rising temperatures, and an increase in both draught and flooding will have a negative impact on crops. Rising sea levels will mean that a great deal of farmland will simply be underwater and no longer available for use. Of course, this will have many other negative effects on food availability beyond agriculture. The increasing rate of species extinction is going to eliminate large sources of food. The damage to our oceans will do the same for supplies of fish, crustaceans and other animals.
History shows us what happens when humans overshoot their carrying capacity. A famous example is that of Easter Island. The island was originally heavily forested and home to a wide variety of species. However, the inhabitants gradually proceeded to deforest the entire island, destroying an ecosystem home to many food sources, and eliminating supplies of wood needed to make boats, meaning that off shore fishing was no longer be possible. This resulted in a population crash from as many as 20,000 people to only around 2,000 when Europeans first visited the island. Things were so bad, they even resorted to cannibalism.
A recent report says that humans have already exceeded the carrying capacity of the planet by 25 percent, and that by 2050, if current trends continue, we would need the resources of two Earths to support ourselves. They also mention that we are on the verge of a large-scale ecological collapse because of species and ecosystem loss. Clearly, if this damage continues, we are unlikely to still be growing by 2050.
Human population has already reached (and surpassed) sustainable levels, given our current level of resource consumption and damage to the environment. It is possible that we could raise the planet's carrying capacity to some degree if there were a massive effort to reduce overconsumption, carbon emissions, pollution and environmental damage. Without such efforts, nature will correct the overshoot herself.
Posts
10 comments:
"It is possible that we could raise the planet's carrying capacity to some degree if there were a massive effort to reduce overconsumption, carbon emissions, pollution and environmental damage". I agree, however given mankinds past & current actions, I don't see many wanting to give up their life of consumption at any cost:(
BTW, my hubby is a canuck, from Cornwall :) oh, and great blog too:)
Hi Molly, thanks for the comments.
I agree, a voluntary reduction in consumption doesn't seem very likely right now. Perhaps when things get bad enough, people will finally realize we need drastic changes, but by then it will be too late.
At the same time, though, during WWII people sacrified a great deal. People accepted rationing, car travel was largely banned except for official purposes, and factories were all converted to war production in a matter of months. This should at least show that it *is* possible to make massive changes quickly when we absolutely have to.
Perhaps the current generation is just too spoiled or entitled compared to that of our grandparents. :(
Great post! Yes, the speed at which things were accomplished for wartime (where people kill each other) is amazingly fast compared to the speed at which people/ gov'ts are willing to make changes to accomplish things for environmental stability (where we are trying to save people)!!
"Organic farming methods can produce stable production over the long term, in a sustainable way, but they cannot produce as much food."
This is not true. In Burma where the average plot of land tended per person is 1/2 acre, the food production is 6x higher per unit area than in industrial agriculture in the West.
Rice grows in shallow ponds where algae fix nitrogen and carbon, enriching the soil. Rice can be grown indefinitely in the same pond without fertilizer, because of this. Rice produces so much food on such a tiny amount of land that merely shifting from corn to rice would enormously increase the food supply.
When less than 2 people in 100 are farmers, society is having no problem growing the food it needs. We could grow food on rooftops if the demand was there. The fact that the demand isn't there means that we are nowhere close to the "carry capacity" of this planet.
Hi Ken. I agree that organic methods can be superior in some areas, and in others, we need them because industrial methods are depleting the soil. At the same time, I don't think we can switch everything to organic overnight, it has to be a gradual process. I discuss this in a bit more detail in another article called Organic Myths and Realities.
Also, keep in mind that the carrying capacity isn't fixed. It varies as we either improve, or damage, the environment. Recent studies show we are over the carrying capacity now, because we are depleting the landbase we need for future food production, among other reasons, yet our population is growing at the same time. If we were to stop doing this (and maybe change some crops as you suggest), and even reclaim some land for agriculture, then we could possible raise the carrying capacity of the planet, and we would no longer be in overshoot. However, this would require some pretty massive changes.
Thanks for such a thoughtful post. I agree that we're well beyond carrying capacity, but how it will all fall out, I don't know.
Leanne at Cluttercut
Was reading your post on organic farming, when I saw your post on this topic mentioned, so I decided to come over and see what it was like.
Thanks for the simple, though not simplistic, take on this.
Too often, so it seems to me, the issue of carrying capacity and overpopulation has been used as a means by some people and groups for advocating the destruction of some sorts of people for whom they don't care, or actively hate.
As a high-functioning autistic man, I am concerned about who would get to set the rules for who's "necessary" and who's "expendable", and who would become their victims.
Too often, it has been, and is, generally the poor and working-class, and other such groups, who have had to pay the majority of the price for whatever social, political and economic decisions their so-called betters have made.
Racism, class snobbery, and other forms of bigotry could be disguised as concern for the environment and the survival of humanity by decision makers, whether intentionally or not(am a believer that much of human decision making comes more out of habit than anything else, including intellectual habit), and be used as an excuse for genocide.
One other thing, and that's about consumption reduction. It may indeed be a good thing to do, and perhaps some form of rationing, a la what the combatant states did in WWII, may need to be imposed at some point.
Have some cautionary words about that, though. One, there is a kind of Left puritanism, especially regarding production and consumption of goods, that I find just as preference-based and repugnant as I do Right puritanism, with its fear and horror of sex and drugs. Again, any process of creating and rationing goods must, in my view, take three considerations into account, the first being precisely what categories of goods are most abundant and necessary to produce and distribute, the second being not just the appearance of, but the reality, of social fairness in this system, and lastly, how to take precautions against and effectively combat black marketeering and corruption in this system, as it will inevitably appear.
In a materially-starved society, it becomes far easier to find and corrupt people, especially those in positions of power, with far less than it would take at present in the developed world.
I believe that austerity isn't a good in itself, nor is poverty, and that, if anything, problems not only in sustainable production of food and other essential goods, but distribution, and the latter is one of the biggest problems we currently have, I think, of those goods to the people who need them.
Sorry if all I've done here is to raise some negative points and criticisms, as I rather like this article, and your one on organic farming.
Thanks for your attention and time in reading this, and sorry for the long comment here.
Hi Donald, thanks very much for your comments. You're certainly right about overpopulation, discussions about this often have racial overtones, sometimes subtle, sometimes blatant.
Your comments about how we can reduce consumption and what methods we should use (or not use) are also very important. This is exactly the type of conversation we need to be having. Now that we recognize the danger from global warming, and other environmental damage, we need to work hard to figure out the most effective, least painful, and most equitable ways to do this.
It seems to me that we could reduce a great deal of consumption without any crimp in our comfort.
In the 70s, when asked to do so, Americans radically lowered their energy use.
I used to live in California, and when we had droughts, they would ask us to lower our water use and we did.
There is so much incredible waste now that we could very easily eliminate it, if the will was there.
And we should pay everyone who voluntarily gets sterilized. It should be enough to be an incentive. Maybe $6,000 for women and $4,000 for men.
This would drop the number of unwanted children born and give young people a good chunk of money when they need it.
Many of the babies born now are not wanted. This is stupid and wasteful.
We can stop it without heavy handed government intervention, just with voluntary rewards.
Hi wagelaborer, some good points. People reduced and sacrificed a lot in WWII as well. So we can do it when we need to.
I think financial incentives can probably help in some cases too. Electricity prices here in Ontario will soon be changing so that it costs much more during peak periods than off periods. So this naturally encourages people to reduce energy use. If we expand transit and make it free (I believe some US cities have done this already) many more people will use it instead of cars. The cost of this could be made up through a carbon or gasoline tax. I'm sure there's many other areas where similar things could be done.
Post a Comment