Global warming potential, global warming commitment and other indexes as characteristics of the effects of greenhouse gases on Earth's climate

Abstract

Radiative forcing (RF) is widely used for evaluation of separate radiative active substance effects on climate. For photochemically active greenhouse gases, this effect detachment for the definite radiative active substance content change poses the problem of filtering out of all other chemically connected greenhouse gas effects. Two schemes of RF calculation for such greenhouse gas are proposed and analyzed: the cumulative and the individual ones as the direct generalization of the standard RF definition and the filtering out procedure, respectively. The global warming commitment (GWC) of gas X relative to a standard gas A for time period T is proposed and determined by the same formula, as the well-known global warming potential (GWP) of gas X , but for different integrated radiative forcing (RF). RF X ( t )=Δ F X ( t ) is the net total radiation flux change at the tropopause level caused only by a gas X content variation during the period of integration. In the GWP of a gas X , Δ F X ( t ) and Δ F A ( t ) appear due to instantaneous releases into the atmosphere of the same definite mass (1 kg) of gas X and of a standard gas A . In the GWC, the actually measured or modeled gas content evaluations are used for the estimation of gas X relative input into the current and future greenhouse warming. The GWC of the principal greenhouse gases (GG) are calculated and analyzed for the period before 1995, calculations and analysis being based on the observed GG content evolution. For this period and for the period from now until 2050, the global GG content evolution reconstruction and prediction by means of radiative photochemical atmospheric model are based on two of the well-known IPCC scenarios of GG anthropogenic emissions. The GWCs of CH 4 , N 2 O and chlorofluorocarbons (CFCs) against CO 2 as a standard GG are different from their relative RF and much more accurately reflect the real events in the above mentioned periods than the widely used RF of GG relative to RF of CO 2 , when the character of the GG content evolution during the time period considered is not accounted for. The filtering efficiency of cumulative and individual schemes is estimated.