The U.S. experienced two very hot summers in 1997 and 1998. Scientists are concerned about the small amounts of CO 2 and other gases that are notsequestered and drift to the upper atmosphere. The upper atmosphere contains a layer of water vapor and other gases that trap some of the sun's energy and reflect it back to earth. Without this insulating blanket, the earth would be an uninhabitable, cold place. Carbon dioxide, however, pales in comparison in its global warming capability to simple water vapor, which composes 97 percent of the earth's insulation.
Water vapor comes from evaporation from the earth's water and soils.
The other three percent of the warming blanket is composed of what are called greenhouse gases -primarily carbon dioxide. Of this three percent, manmade releases of carbon dioxide and the other greenhouse gases amount to about five percent of the total. Put another way, if all of mankind's greenhouse gas emissions were shut down, 99.85 percent of the earth's insulating blanket would remain. Those advocating dramatic and expensive actions to reduce global warming seldom mention this fact. This sounds like a lot, but keep in mind that if these U.S. emissions were stopped completely, 99.97 percent of the global warming blanket would remain.