evidence: The earth's temperature, then, is primarily determined by the planetary radiation balance, through which the absorbed portion of the incoming solar radiation is nearly exactly balanced over a year's time by the outgoing terrestrial infrared radiation emitted by the climatic system to earth. As both of these quantities are determined by the properties of the atmosphere and the earth's surface, major climate theories that address changes in those properties have been constructed. Many of these remain plausible hypotheses of climatic change. Certainly the natural greenhouse effect is established beyond a reasonable scientific doubt, accounting for natural warming that has allowed the coevolution of climate and life to proceed to this point ( e.g., see Schneider and Londer, 1984). The extent to which human augmentation of the natural greenhouse effect (i.e., global warming) [...] Mass, C. and S. H. Schneider, 1977. ``Influence of sunspots and volcanic dust on long-term temperature records inferred by statistical investigations''. J. Atmos. Sci. 34 (12): 1995-2004. [...] Human beings increase the concentrations of greenhouse gases in the atmosphere primarily by the burning of fossil fuels--coal, oil and natural gas--and through a number of other industrial processes.