The topic of global warming generates a great deal of heat but very little light. There are several things that we know and a number of things we do not know. We have an almost endless supply of data, but very little knowledge. As Einstein said, “Information is not knowledge.” However, there are several things we do know. Among these are:

1. The earth is in an interglacial cycle. This cycle began around 15,000 years ago when ice laid 3 miles thick over what is now Chicago and sea level was some 300 feet lower than it is today.
2. The earth has warmed and cooled during this last 15,000 years including such periods as the medieval warming period and the little ice age.
3. The rate of sea level rise shows no evidence of significant change at this time. Sea level has obviously risen during this interglacial period and continues to do so. The best estimate of the current rate of rise is 2mm per year (less than one foot per century).
4. There is no ‘normal’ climate during an interglacial period. The earth’s normal climate is glacial, a prospect that makes any suggested level of global warming seem very desirable.
5. CO2 is a greenhouse gas, however its effect is logarithmic not linear. The best way to explain its impact that I have found is an analogy to a piece of plate glass being painted with successive thin costs of paint. The first coat cuts light transmission dramatically, the second less so, the third by a negligible amount, etc.
6. The United States is not the largest emitter of greenhouse gases and nothing we do will slow the increase in environmental CO2 levels. Coal is the most efficient fuel for the generation of electricity and world usage is expected to skyrocket.