Human Population Growth: Life in a Dome - Epilogue

Part II.  Epilogue:  Life in a Dome

Columbia University Biosphere 2 Center was a living experiment in a glass dome.  Eight people were sealed in the dome in 1991, but Biosphere 2 failed to sustain these eight scientists for even two years.  By 1993, the oxygen concentration in the air inside Biosphere 2 fell to 14%—roughly equivalent to that at the peak of a 17,500-ft mountain.  Atmospheric CO2 rose to about 1700 parts per million (ppm), similar to a level last seen approximately 50 million years ago shortly after the extinction of the dinosaurs.  Nitrous oxide (N2O), a trace gas emitted from the microbial decomposition of soil nitrogen, rose to 79 ppm—a level that can reduce vitamin B12 synthesis to levels that damage the brain.  Species extinctions were startling.  Nineteen of the 25 vertebrate species in Biosphere 2 went extinct.  All pollinating species went extinct, in part because ants took over the insect world, forcing the researchers to pollinate plants themselves.  In 1993, fresh air was pumped into Biosphere 2, the researchers were able to leave the system, and the test was over.

Why did Biosphere 2 fail?  Much of the answer lies in the fact that researchers did not correctly judge the quantity of different ecosystems that were needed to sustain human life, and they did not anticipate how the entire system would adjust after it was sealed off.  Specifically, too much soil was added in the tropical rainforest biome.  The microbes in the soil, under the warm conditions in Biosphere 2, decomposed the soil carbon, releasing CO2 to the atmosphere and consuming O2.  This, in part, drove down the quantity of breathable air and created a greenhouse effect with the high CO2.  Another factor that contributed to the decline in oxygen was the cement materials use to construct the foundation.

Other surprises included the collapse of the animal kingdom and the elimination of insect species valuable for ecosystem services like pollination.  Ecosystem services are invaluble to humanity and, if degraded, can prove impossible or too costly to replace.

Biosphere 2 and the ecological footprint are valuable lessons about sustainability.  Even in our best attempt to sustain the lives of just eight people, we could not develop an artificial biosphere that was sufficient.  Consider what would be required for a glass dome over your house, town, city, or country to perform any better.   Consider all of the essential ecological services that our planet performs for use. 

The Final Assignment - Inform the CofC!  

Your mission for this problem, if you choose to accept it,  is to write article (or editorial) for the CofC student newspaper on whether or not your generation should be concerned about the impact that human population growth is having on the ecological services provided by the earth's ecosystems. 

Before you write your article you should read the following two articles by author’s who clearly have different stances on this issue.

As you read these two articles,  assess their merits critically.  Use the following: Questions to Ask When Examining Positions, and Propaganda Alert to help you critically assess these issues articles.

If you agree that human population growth is having a significant negative impact on the earth's ecosystems and the essential life supporting ecological services they provide then be sure to discuss the following:

If you feel that human population growth is not  likely to have a significant impact on the earth's ecosystems and the essential life supporting ecological services they provide then be sure to discuss the following:

Assignment Guidlines:

Other research resources which may be helpful in writing your article