Читать книгу Practical Sustainability Strategies - George P. Nassos - Страница 38

This means that materials like fossil fuels, metals, minerals, and other natural resources must not be extracted from the earth at a faster rate than they are reentering or depositing into the earth's crust or even its atmosphere. A good example of violating this condition is the extraction of fossil fuels like oil or coal. When the fossil fuel is combusted, the carbon in the coal, for instance, is converted to carbon dioxide. For most of the human existence, the carbon dioxide emitted would eventually be reabsorbed by trees and other vegetation. The rate of emitting carbon dioxide was equal to the rate of absorption. Consequently, the carbon cycle was in balance and there was no violation of System Condition 1. The concentration of carbon dioxide was consistently about 280 ppm. However, we are now emitting carbon dioxide at a faster rate than it is being absorbed, thus causing an increase in the carbon dioxide concentration in the atmosphere—exceeding 400 ppm. This cover of carbon dioxide is preventing the release of reflected sun rays back into the atmosphere, thus causing an increase in the temperature of the Earth—global warming, which is also known as climate change.

If this condition is not met, the concentrations of substances in the ecosphere will increase and eventually reach some limits beyond which it will be almost impossible to reverse. In the case of carbon dioxide, many scientists believe that it will be impossible to reverse, even if we stopped emitting carbon dioxide. In a report by the National Oceanic and Atmospheric Administration, it stated that “changes in surface temperature, rainfall, and sea level are largely irreversible for more than a thousand years after carbon dioxide emissions are completely stopped.” In an interview with the lead author, Susan Solomon, she said, “People have imagined that if we stopped emitting carbon dioxide that the climate would be back to normal in 100 or 200 years. What we're showing here is that that's not right” [4].