While I know many of you are aware of the basic facts, I think it may be useful to reiterate a few of the most crucial points that the scientific community has established. The natural levels or concentrations of these greenhouse gases in the atmosphere keep temperatures within a range that can support life. Without the background level of greenhouse gases in our atmosphere, the earth's temperature would be about 33 degrees Celsius cooler. Changing land use patterns, particularly deforestation and soil erosion, also play a role, by reducing the capacity of the natural environment to absorb carbon from the atmosphere. Since pre-industrial times, the Earth has warmed about one degree Fahrenheit.
Scientists believe that the observed increase is unlikely to be entirely natural in origin.
Projections of future climate change, based on complex climate models and on our best understanding of the physics of the climate system, suggest a rise of another two to six and a half degrees Fahrenheit by 2100, with an average increase greater than any seen in the last 10,000 years. This warming will not be uniform - it is likely to be greater at higher latitudes and at the poles. Based on these warming trends, sea level is projected to rise an additional one and a half feet by 2100 due to thermal expansion of the oceans and to the melting of glaciers and ice sheets. This would, without adoptive measures, flood 9,000 square miles of coastal areas here in the United States, notably in Florida and Louisiana, and put about 100 million people world-wide at risk each year from storm surges. In other words, the path we are on is cause for significant concern.