Unlike the rest of the world I believe that global warming is caused by heat and not greenhouse gases. If you do a heat balance on the biosphere, the incoming and outgoing heat rates must be close to equal for an equilibrium condition to exist, for global warming the incoming rate must be greater than the outgoing rate. Heat disapation is through radiation, conduction, convection, etc. The primary source of incoming heat energy is the sun with significant contributions from terrestial sources. Since nuclear energy releases stored potential energy from the earth, is contributes a little bit to global warming. As more energy is released by burning trees on a global scale this is the primary cause of global warming. This has the compounding effect of destroying a heat sink for incoming solar radiation. Trees convert solar energy into their life mass. About 0.2% of the world is being deforested each year and this is the major cause of global warming. As it turns out, the burning of wood creates greenhouse gases corresponding to the heat that is producted, therefore, it is only incidental that the concentration of greenhouse gases is proportional to global warming.