Radiative forcings and global warming potentials of 39 greenhouse gases

Abstract

Abstract. The radiative forcings and global warming potentials for 39 greenhouse gases are evaluated using narrowband and broadband radiative transfer models. Unlike many previous studies, latitudinal and seasonal variations are considered explicitly, using distributions of major greenhouse gases from a combination of chemical-transport model results and Upper Atmosphere Research Satellite (UARS) measurements and cloud statistics from the International Satellite Cloud Climatology Project. The gases examined include CO2, CH4, N20, plus a number of chlorofiuorocarbons, hydrochlorofiuorocarbons, hydrofiuorocarbons, hydrochlorocarbons, bromocarbons, iodocarbons, and perfiuorocarbons (PFCs). The model calculations are performed on a 5 ø latitude grid from 82.5øS to 82.5øN. The radiative forcings determined by the model are then used to derive global warming potential for each of the compounds, which are compared with prior analyses. In addition, the latitudinal and seasonal dependence of radiative forcing since preindustrial time is calculated. The vertical profiles of the gases are found to be important in determining the radiative forcings; the use of height-independent vertical distributions of greenhouse gases, as used in many previous studies, produce errors of several percent in estimated radiative forcings for gases studied here; the errors for the short-lived compounds are relatively higher. Errors in evaluated radiative forcings caused by neglecting both the seasonal and the latitudinal distributions of greenhouse gases and atmospheres are generally smaller than those due to height-independent vertical distributions. Our total radiative forcing due to increase in major greenhouse gas concentrations for the period 1765-1992 is 2.32 Wm -2, only 2% higher than other recent estimates; however, the differences for individual gases are as large as 23%.

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

“…Anthropogenic emissions of GHGs, such as CO 2 , CH 4 and N 2 O, continue to increase these tropospheric gas burdens. For example, the 5 Gt of methane in the atmosphere today raises the global temperature by approximately 1.3 K (Donner & Ramanathan 1980), and the change in forcing by methane since 1750 has been 0.55 W m K2 (Minschwaner et al 1998;Jain et al 2000). Our knowledge that these changes are occurring are founded on meticulous time-series trace gas measurements, such as the NOAA CMDL CCGG cooperative air sampling network (e.g.…”

Cavity Ring-Down and Cavity-Enhanced Detection Techniques for the Measurement of Aerosol Extinction

“…The atmospheric extinction of electromagnetic waves in the visible and near-visible spectral regions influences the earth's climate by changing short-wave radiative forcing (Jain et al 2000;Reddy and Venkataraman 2000) and influences optical remote sensing by ground-based, airborne, and satellite systems (Schott 1997), including visual perception by humans (Chow et al 2002;Watson 2002). Optical extinction in the atmosphere is due to scattering and absorption by both particle-free air and aerosols.…”

Coordination studies with PNNL's global change assessment model: integrated science modeling and applications to the human dimensions. Final technical report for period October 1996 - March 2000

“…In order to examine the sensitivity of the radiative forcing to the vertical, and regional and seasonal greenhouse gas distribution, we estimated regional and seasonal changes in the vertical distribution of greenhouse gas concentrations using our two dimensional chemical transport model (CTM) (Jain et al, 2000). Figures 2,3 and 4 show the comparison of CTM estimated regional changes in vertical distributions of C b , N20, and CFC-12 for the September-October current atmosphere.…”

“…Even the international assessments (such as IPCC and WMO) used these diverse results for their assessment of greenhouse warming impact. The unique aspect of our study is its attempt to resolve inconsistencies in previous evaluations of radiative forcings by adopting a uniform approach and investigate the role of spatial and temporal resolution in estimating radiative forcing due to thirty-nine important greenhouse gases using distributions of major greenhouse gases based on chemical transport model results and measurements, in combination with a more accurate modeling approach -a narrow-band radiative transfer model of the global atmosphere (Jain et al, 2000). Figure 5 shows the estimated monthly mean radiative forcing changes as a function of latitude for the period 1765-1992 for major greenhouse gases.…”

“…We evaluated, in a consistent manner, the radiative forcing due to changes in the concentrations of various important greenhouse gases , Jain et al, 2000Li et al, 2000). In general, IAM use a simple relationship to calculate the radiative forcing of greenhouse gases.…”