Wednesday, July 28, 2004

Carrying Capacity
I recently mentioned, during a conversation, that I wish politicians would discuss population control when they talk about the environment. Someone asked me what I meant by that, so I explained briefly how the global population is growing and how all our problems like jobs, poverty, hunger, disease etc would be easier to fix if there were less people on the planet. I explained that I wasn't talking about killing people off or anything, just making people aware that having less children, or no children at all, can have a great positive effect on the environmental impact of humans. I then went and found a book I recently read, The Ecology of Commerce, and pulled the following few paragraphs out of it because I think they sum up the issue really well.

Because resource supplies are declining, we as a species are exceeding our "carrying capacity" --the uppermost limit on the number of species an ecosystem or habitat can sustain, given the supply and availablity of nutrients. In island systems, where ruminants browse and graze, grass, leaves, and berries might be the chief limiting factor to carrying capacity. In the Sahel desert, brushwood used for cooking might be the limiting factor on the human population. The industrialized world has more extensive needs and wants, so a larger number of resources can become limiting factors. Not only food, but fuel, water, electricity, and cars--the "food" of our industrial civilization--can serve as limits to carrying capacity. What is most dismaying about our political and commercial unwillingness to examine such limits on a global level is that there is absolute agreement on what it means on a local level. Range managemnt experts can properly assess grazing limits that maximize yield while preserving the health of a habitat. In a pasture or range, one can temporarily increase herd size and output, but it is a short-lived phenomenon that eventually results in lower production and eroded soil, requiring a long period of recovery. Estimating carrying capacity of fisheries and other large, complex systems is difficult, and not always accurate, partially due to inexperience and lack of concerted effort. Transnational corporations, the World Bank, and politicians have not yet determinedly integrated the processes involved with the estimation of carrying capacity into the act of development. Exceeding carrying capacity does not prove that carrying capacity does not exist, but merely that we know how to evade it temporarily, further damaging the sustainable yield of a given habitat.

Natural and human history are full of examples in which animals or humans exceeded carrying capacity and went into steep declines, or extinction. A haunting and oft-cited case of such an overshoot took place on St. Matthew Island in the Bering Sea in 1944 when 29 reindeer were imported. Specialists had calculated that the island could support 13 to 18 reindeer per square mile, or a total population of between 1,600 and 2,300 animals. By 1957, the population was 1,350; but by 1963, with no natural controls or predators, the population had exlploded to 6,000. The original calculations had been correct; this number vastly exceeded carrying capacity and was soon decimated by disease and starvation. Such a drastic overshoot, however did not lead to restabalization at a lower level, with the "extra" reindeer dying off. Instead, the entire habitat was so damaged by the overshoot that the number of reindeer fell drastically below the original carrying capacity, and by 1966 there were only 42 reindeer alive on St. Matthew Island. The difference between ruminants and ourselves is that the resources used by the reindeer were grasses, trees and shrubs and they eventually return, whereas many of the resources we are exploiting will not.

Until recently, declines or wipe-outs of species were largely local problems because carrying capacity was a local phenomenon. Today, industrial civilization has increased the reach of human beings, at least the wealthier peoples, far beyond their own lands to the entire world. Tropical forests in Brazil have been razed to grow soybeans which are fed to cows in Germany that produce surplus butter and cheese that is piling up in refrigerated warehouses. This artificial ecosystem has "increased" Germany's carrying capacity, but drastically lowered it for one million displaced forest settlers now disenfranchised and living in squalor in Rio de Janeiro and other urban centers.

Because richer northern countries do not see or experience the impact they have on their poorer southern nations, we do not realize what a powerful and destructive impact our demand on carrying capacity is having. In the same time it takes to read this page, one hudred people will have succumed to pesticide poisoning: 48 per minute, 25 million every year. In some Third World countries, pesticides kill more people that do major diseases. Because we have globalized our capacity to draw from an expanded environment, our world appears to be more secure and stable. While, for example, food surpluses from one region can be shipped to drought-stricken areas, preventing starvation and disease, such [assistance in time of distress] can be maintained only if the overall impact by humans is less than the overall carrying capacity. This, in fact, is the opposite of what is occurring.

Now, if that's not an argument in favor of anal sex, I don't know what is. Plus, if you're the religious type, in-the-butt doesn't count. Every Catholic schoolgirl knows that! This might come in handy though.

That's right, this post has just made me the only person on earth who's ever been able to successfully make turd-burglary an environmental issue. Tomorrow we'll discuss how you can save baby seals by getting hummers.

Ah how my blog is so educationally crass. I love it.