On balance, CFCs and aerosols have probably moderated any recent warming. In fact nature, through such activities as the decomposition of organic matter on land and in the oceans, contributes 93 to 97 percent of the atmospheric CO 2 . Out of approximately 160 billion metric tons of CO 2 exchanged in the atmosphere every year, humans contribute only 5.6 to 8.6 metric tons. Scientific-Technical Analyses, p. 77. None of these analyses considers increased CO 2 beneficial.
Previous analysis suggests a flat marginal benefit curve.
55-77, explain that marginal benefit costs are essentially unaffected by the emissions levels in any given decade. This conclusion rests on the finding that temperature change depends on gas concentration, which is not greatly affected by emissions levels in any given decade. I follow this characterization by assuming horizontal benefit curves that depict a constant level of benefits for any level of CO 2 abatement. The author developed the analytical framework and simulation model with Hillard G. Huntington of Stanford University. The DOE projections represent one of many possible world energy outlooks for 2010.