  The clear sky instantaneous radiative forcings of the 14 halogenated gases
previously shown to have the largest contribution to global warming, were
found. The calculation used the absorption cross sections for the halogenated
gases which are assumed to be independent of temperature as well as over 1/3
million line strengths for the 5 naturally occurring greenhouse gases: H$_2$O,
CO$_2$, O$_3$, CH$_4$ and N$_2$O, from the Hitran database. The total radiative
forcing of the halogenated gases at their 2020 concentrations is 0.52 (0.67)
W/m$^2$ at the tropopause (mesopause). Over half of this forcing is due to
CFC11 and CFC12 whose concentrations are declining as a result of the Montreal
Protocol. The rate of total forcing change for all 14 halogenated gases is 1.5
(2.2) mW/m$^2$/year at the tropopause (mesopause). The calculations assumed a
constant altitude concentration for all halogenated gases except CFC11, CFC12
and SF$_6$. Using the observed altitude dependence for those 3 molecules
reduced their radiative forcings by about 10%. The global warming potential
values were comparable to those given by the Intergovernmental Panel on Climate
Change. The contribution of a gas to global warming was estimated using the
forcing power per molecule defined as the derivative of its radiative forcing
with respect to its column density. For the present atmosphere, the
per-molecule forcing powers of halogenated gases are orders of magnitude larger
than those for the 5 naturally occuring greenhouse gases because the latter
have much higher concentrations and are strongly saturated. But, the rates of
concentration increase of the 5 main greenhouse gases are orders of magnitude
greater than that of any halogenated gas. Assuming the temperature increase
caused by each gas is proportional to its radiative forcing increase, the 14
halogenated gases are responsible for only 2% of the total global warming.
