April 18, 2014

Carrying Capacity of the Earth

The current estimated population is around 6.6 billion people and climbing rapidly. How rapid is this climb is a difficult question to answer. When considering the overall global growth rate, we reached a peak of 2.04% annual increase in the 1960s and it has been dropping since. However, any kind of rate increase from a base of 6.6 billion means a lot more people. It’s important to note that many modern industrialized countries are currently experiencing a decrease in population, but developing countries are going in the reverse direction. The rough projection for world population in 2050 is 9 billion, which almost all of this growth in less developed countries (for this projection, developing countries means everywhere besides Europe, North American, Australia, New Zealand, and Japan).

This leads to a compelling question: are there enough resources for 9 billion people? In scientific terms, what is the carrying capacity of Planet Earth?

Carrying capacity is a term used in biology to describe how much life an area of the biosphere can sustain. For example, the carrying capacity for an African savannah is evaluated on multiple levels: how many plants can grow in relation to the fertility of soil, rain, and sunlight, how many gazelles can be fed by this plant growth, and how many lions can be fed by the number of gazelles. To be more specific, if a lion can’t catch enough gazelles they will either starve to death or be too malnourished to reproduce.

The carrying capacity for human beings is way more complex because we have far more control over our environment and our life situation. Plus, when there are instances when populations of humans are hit by famine, it’s completely immoral to standby and just say “well, they are hitting their carrying capacity”. In addition to the famine, populations running low on resources are ripe grounds for social instability like terrorism and genocide.

As globalization roars around the world, more and more people will start to enjoy a higher standard and they will consume more and more precious resources. While this is happening, these people will start having less children and these “nearly developed” countries will start having population decreases like the developed world.

So, in theory, as the world modernizes the population will start to drop and our problems will be solved. Unfortunately, it’s difficult to say if we can get through the transition without serious problems. “Transition” is very vague word and it’s unclear how low our population needs to go. One study projected the carrying capacity of the Earth in 2100 (assuming a modest standard of living) will be 2 billion worldwide. This figure was determined by Cornell researches by analyzing human needs for fertile land, fresh water, fossil fuel energy and a diversity of helpful natural organisms. What’s interesting about the 2 billion figure is the fossil fuel component because it’s the only non-renewable resource in that list…if you didn’t need any more proof how important alternative energy is.

Considering how difficult figuring out the carrying capacity is, let’s just go with 2 billion without talking about other studies. Trimming down the current population to a mere 2 billion in 93 years is the tallest of tall orders. Obviously we have to be ethical about this and we have to avoid policies like China’s one child rule (which has lead to female infanticide and the huge imbalance of males to females could lead to massive societal problems for China in the future), but we will have to take aggressive steps in promoting contraceptive use in developing countries and using the best technology is conserve energy, product biodiversity, protect the fertility of soil, and avoid diminishing our fresh water sources. It may also require some innovative ideas like increased immigration to developed countries and promoting international adoption instead of having biological children. I’m currently single, so raising kids is something I really don’t think about much right now but adopting children from China or Iraq has its appeal for the above reasons. Of course, a future wife and I may want to have biological children, but the decision to bring more children into this world could become very complicated in the near future. Cornell researcher David Pimental laid out the stark truth very well: “You have to take your choice. People say that they should have the freedom to reproduce. I’m sympathetic to that view. But you’re going to either lose some of that freedom, or your children and your grandchildren will lose some of their freedoms: freedom from starvation, freedom from disease. —- If we refuse to reduce our numbers ourselves, nature will find much less pleasant ways to control human population: malnourishment, starvation, disease, stress and violence.”

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Posted by Tim Roth, author of the political blog Think Anew and Act Anew

Sources:
1. World Population Clock, U.S. Census bureau

2. “Way Too Many For Us” by Hillel J. Hoffmann, Cornell University Alumni News