Human Population Growth and the Environment

by John S. Peters, Dept. of Biology, College of Charleston
Aspects of this Case Study are borrowed from, Watch Your Step by Philip Camill, Department of Biology, Carleton College

Part I. Future Imperfect?

Imagine you could see into the future and watch the next 100 years unfold. Let's say that human populations, resource consumption, and waste continue to grow according to a business-as-usual scenario with few changes in policy or lifestyles to curb these trends. Would you notice a point when Earth is no longer able to sustain human population growth, resource consumption, and pollution? Have we already reached this point? How could you tell? What does it take to sustain life on Earth? The issue of sustainability is a challenging one, and the long-term survival of life as we know it may depend on how we define sustainability as well as the policies and lifestyle changes necessary to achieve it.

Understanding how the Earth system sustains human life is a fascinating problem. Interestingly, space travel provided an early impetus for creating artificial life-support systems based on ecological principles similar to those of Earth's biosphere. The goal was to develop a self-sustaining biosphere in miniature that could extend the duration of space flights or allow humans to colonize another planet like Mars. In 1984, a company called Space Biospheres Ventures began the most ambitious example of this kind of research project called Biosphere 2 to replicate a self-sustaining biosphere like Earth's (a.k.a. Biosphere 1).

Columbia University Biosphere 2 Center has become an important experiment for understanding the life-support functions of the biosphere. Simply put, do we know enough about how the Earth's biosphere sustains human life to be able to replicate it or preserve it.

Between 1984 and 1991, Columbia University Biosphere 2 Center was built in Oracle, Arizona, at a cost of over $200 million. The structure was not just a building where people could attempt to live sustainably it was much bolder. Biosphere 2 was a giant glass chamber sealed off from the atmosphere that contained living ecosystems including a tropical rainforest, ocean, savannah, desert, marsh, and agricultural landscape. It enclosed 13,000m² of land and a total volume of 204,000m³.

The original test of Biosphere 2 attempted to determine if these ecosystems could support the lives of eight people in perpetuity. All that would support these 8 people would come from within the sealed Bioshpere (except for sunlight). Their only source of food was what they could grow in the agricultural sector. Their only source of oxygen was from plants and algae in the terrestrial and oceanic ecosystems. In 1991, the eight researchers were sealed in Biosphere 2, and the world watched. What happened? Well, you'll just have to wait and see! We will see the outcome of the Biosphere 2 experiment at the end of the case.

Imagine you are a team of senior research scientists at the initial planning phase of Biosphere 2. What kinds of specific conditions would be needed in Biosphere 2 to make it possible to sustain eight people for the rest of their lives? You might consider the following questions and sources of information:

Should the eight researchers' diets be vegetarian or meat-based? What difference would this make?
Should they make/use artificial fertilizers to enhance the growth of their crops?
Are the ecosystem types referred to above sufficient to sustain people?
Should other animals be included in Biosphere 2? If so, what kinds and why would they want them there?
How might driving a car in Biosphere 2 affect the sustainability of the eight people?
How would other aspects of our daily lives, which today we consider basic necessities/rights in a "civilized" society (air conditioning/refrigeration, heating our homes, lighting, the clothing we wear, having children, owning property) affect the sustainability of the eight people.

Homework Reading - Consider the questions above in light of the reading for next class (Chapters 40.12-13; 41 (and parts of 42 as needed) in your textbook and
Ecosystem services: Benefits supplied to human societies by natural ecosystems. There will be a RAT over these questions next class!