A Simple, Physics-Based Calculation of the Global Warming Climate Sensitivity

Major results in physics can often be understood on the basis of simple physical arguments. An important scientific issue of societal import is global warming due to increased carbon dioxide content in the atmosphere. In this paper, I describe an attempt to calculate the Climate Sensitivity, defined as the global mean temperature increase due to carbon dioxide doubling, from simple analytic arguments. The discussion relies on the astrophysical concept of the equivalent width as a measure of the strength of a stellar absorption line. An equation is derived which yields a value of about 2.0K for carbon dioxide doubling, a value in reasonable agreement with a value of 1.0 - 1.5K from climate models. However, the derivation also reveals limitations of this simplified approach.