Pollution Prevention and Reduction Greenhouse gases are
essential to life on earth. Without them, much of the sun's
energy that warms the earth would be lost and temperatures would
be about 60 degrees lower than they are now. But greenhouse gas
concentrations are actually increasing, leading to a rise in
global temperatures. The U.S. Global Change Research Program
reports that the average U.S. temperature has increased more
than 2 degrees during the past 50 years. It is expected to rise
another 4 to 11 degrees by the end of this century, depending on
emission scenarios. Researchers attribute these increases
primarily to burning fossil fuels like coal, oil and gas along
with clearing forests, agricultural practices. and other
activities. Some scientists are concerned that as greenhouse gas
concentrations continue to rise, global temperatures may
increase further and contribute to climate change. This could
raise the level of the oceans and disrupt food production, along
with other effects. What TVA is doing ab