Energy from the heats the earth’s surface; in turn,
the earth radiates energy back into space. Atmospheric greenhouse
gases (water vapor, carbon dioxide, and other gases) trap some
of the outgoing energy, retaining heat somewhat like a greenhouse.
This natural effect keeps the earth’s average temperature at about
60°F and allows life as we know it to flourish. However, increases
in atmospheric concentration of greenhouse gases have enhanced
the heat-trapping capability of the earth’s atmosphere. Since
the beginning of the industrial revolution, atmospheric concentrations
of carbon dioxide have increased nearly 30%. Scientists generally
believe that the combustion of fossil fuels and other human activities
are the primary reason for the increased concentration of carbon
dioxide. Energy consumption is responsible for about 80% of society's
carbon dioxide emissions. Increased agriculture, deforestation,
landfills, industrial production, and mining also are mojor contributors.
shown provides information about the atmospheric concentration
of carbon dioxide since 1960, measured in parts per million.