This climate model uncertainty is distinct from the high social uncertainty is distinct from the high social uncertainty associated with future scenarios of greenhouse gas and airborne particle concentrations. I assume that detailed future greenhouse and airborne particle scenarios are part of the policy question and thus do not discuss them further. Some of my evaluations differ in detail from those of IPCC 1996, mostly because of the addition of new research insights and information since 1994. In effect, if we disagree scientifically with IPCC, we should explain why. Without such discipline, contrary arguments are not likely to be scientifically sound.
Greenhouse gases absorb and re-radiate infrared radiation efficiently.
This property acts directly to heat the planet. Altered amounts of greenhouse gases affect the climate for many centuries. The major greenhouse gases remain in the atmosphere for periods ranging from a decade to centuries. Also, the climate itself has considerable inertia, mainly because of the high heat capacity of the world ocean. Changes in other radioactively active substances offset somewhat the warming effect of increased greenhouse gases.