Greenhouse gases in the atmosphere ( carbon
dioxide, methane, nitrous oxide, water vapor, etc) act to slow down the
escape of heat radiating from the Earth's surface. Atmospheric greenhouse gases are
increasing. The resulting average international temperature increases
are marked by upward shifts in world wide weather patterns. When
Milankovitch cycles, climatic patterns on Earth brought about by
"orbital forcing", do finally begin to push towards naturally occurring
global warming trends, these cycles will be amplified by our unnatural
levels of greenhouse gases. Even if we had stopped releasing them
yesterday, these gases will remain for millennia. At the ever increasing
rates of the release of these gases, how much will our descendants
suffer because of us? How much does any other issue even compare to this
one? How long before we do enough about the real inconvenient truth
causing global warming: human overpopulation.
http://www.explainthatstuff.com/globalwarmingforkids.html
http://www.nrdc.org/globalwarming/f101.asp
http://www.justfacts.com/globalwarming.asp