As humans start a new millennium, we have close to 4 billion more than we had at the beginning of the last millennium. In the next 50 years we are looking at adding another 3 billion people. Such a rapid increase has placed great strains on the Earth and leads us to ask – how many people can the earth support? The answer is rather obscure, however it seems like we are approaching our limit rather soon. With decreasing aquifers, shortages in food, and increasing pollution, the Earth has reached its limit.
Carrying capacity is defined as the maximum population that can be supported by the available resources while still leaving resources for future generations. All living organisms have this concept behind them. The main factors of food and water and space give a ballpark figure as to how many of one species can live in a certain area. Humans also have a carrying capacity however; unlike our lesser-developed counterparts in the animal kingdom our “certain” area encompasses the whole world. On top of that, our carrying capacity seems to change from time to time. Technological advances in agriculture and in health services have vastly increased life expectancy and other factors of carrying capacity. The first major, change of carrying capacity probably came around the Industrial Revolution, safe water was becoming available, refrigeration was being used, and the advent of the automobile and ship travel allowed humans to spread out and sustain themselves. Even today our carrying capacity is changing, with medical and agricultural breakthroughs being heard of everyday, life expectancy in developed countries is increasing all the time.
As the Industrial Revolution came and went it spawned a rapid population growth. Between 1927 and 2000 the population jumped from 2 billion people to 6 billion people. Many countries have seen this rapid growth and see that it is quite detrimental. Most countries that are considered industrialized have curbed their population growths. Most of Europe has either a growth of 0% or it is in the negative numbers. America is also trying to curb it population growth of 2%. Developing nations are where the population controls are needed. Even among the developing nations there is a divide. One group, exemplified by the Eastern Asian countries have made efforts to keep families small and in return see increased quality of life and falling fertility. The other group of developing nations, mostly comprised of the continent of Africa and the Indian subcontinent, have not addressed the issue of population control. It is these countries that will and in some cases are seeing the effects of overpopulation directly. The indirect effect of these countries, such as migration and social problems will become the problems of countries in Europe and the United States.
The main determinant of the Earth’s carrying capacity can be packaged under the term of sustainable resources. Sustainable resources are resources need for life that are being replenished at the same rate or at a higher rate than it is being used. Resources such a freshwater, cropland and grain, air, habitable land, and forests are resources vital for life. Once abundant and seemingly endless, they have become valuable commodities and are no longer sustainable resources.
One of the main criteria for life is the presence of water. One may say that water has an endless supply and that it provides no worries. This assumption however is wrong. We has human use water in many forms and now we are looking at depleting our supply. Human also limit themselves in the fact that we rely primarily on freshwater for our various activities. Aquifers in India are a prime example of how over population is making resources unsustainable. As population grows the need for water increases. Not only drinking water is needed but also a great portion of India’s farmland is irrigated and so as population increases, food becomes in demand and thus water is crucial in yielding as much possible in terms of crops. India’s water use has gone beyond the sustainable yields of the countries aquifers. With the use of electric and diesel pumps, water is being pumped out at twice the rate rainfall can replenish the aquifers. This results in a 1-5 meter drop in aquifers every year. As this happens, farmers who can afford it, drill even deeper wells. To compound this problem, it is not known how much water is left in India’s aquifers; a decrease in usage of water for irrigation would reverberate through the population. If India, already being a country with 53%of its children malnourished, were to use less water for irrigation, it would mean less to harvest and even more hunger and death. Health wise, aquifer depletion reduces the amount of water that can dilute pollutants. So as toxins or pathogens get in the water they are far more concentrated and thus create epidemics. Also the aquifers have been so depleted that salt water from the oceans is seeping into these pockets where freshwater was stored. The salt water then salinates the freshwater leaving it unsuitable for drinking or irrigation. Economically, the aquifer depletion hurts farmers who cant afford to drill any deeper. These farmers have to rely on the rain and thus crop yield is substantially smaller and virtually not worth the effort in harvesting the food. These farmers then decide to migrate to already over crowed cities leaving behind depleted land. The problem of aquifer depletion is not held just to India, it is prevalent in China, North Africa, the Mid East, and large tracts in the United States also.
In nearly all the countries facing rapid population growth deal with cropland shortage. As more and more people are created the limited land is further and further divided and eventually it will come to a point where the cropland per person drops below a level where a country can feed its own people. A big effect of cropland shortage is migration. People who can no longer live in an area that doesn’t provide enough food leave and move to either urban areas or other farmlands where it has yet to meet its limits. This migration drives poverty even more and also increases the chances for destructive conflict between people.
The third part of the begging of the end for human growth is pollution. Air pollution, land pollution, and water pollution are all taking abundant resources and making them scarce. Smog, carbon monoxide, sulfur dioxide, and various other airborne chemicals are slowly taking clean air away. Clean water is becoming harder to find naturally. Once again the developing countries, the one who need water treatment plants, can not afford them, leaving the people to drink water full of toxins, bio-waste, and deadly pathogens. Finally land pollution is astronomical. The US itself accounts for 25% of the waste in the world and it only holds 6% of the world’s population. Not only waste contributes to land waste, land degradation also contributes to overpopulation. Land once full of life sustaining minerals and resources have been destroyed by deforestation and desertification, rendering them inhabitable and pushing people closer together.
In the end, damage has been done so extensively we can only hope to control the situation. Optimistically, we as humans can hope technology can somehow find a way to keep sustainable resources and to increase the carrying capacity of the earth. However, if the technology did present itself, the countries that need it most would not be able to afford it. The only key to controlling the spin overpopulation has placed the earth in is through education. Education in family planning, education in eco-friendly practices, and educating minds to help solve the problems that we have created basically in the last 100 years are our only hope.
Carrying Capacity of the Earth