As in previous IPCC assessments, AR5 uses the radiative forcing
(RF) concept, but it also introduces effective radiative forcing
(ERF). The RF concept has been used for many years and in previous
IPCC assessments for evaluating and comparing the strength of the
various mechanisms affecting the Earth’s radiation balance and thus
causing climate change. Whereas in the RF concept all surface and
tropospheric conditions are kept fixed, the ERF calculations presented
here allow all physical variables to respond to perturbations except
for those concerning the ocean and sea ice. The inclusion of these
adjustments makes ERF a better indicator of the eventual temperature
response. ERF and RF values are significantly different for anthropogenic
aerosols owing
to
their
influence
on clouds
and
on
snow cover.
These
changes to clouds are rapid adjustments and occur on a time
scale
much faster than responses of the ocean (even the upper layer) to
forcing.
RF and ERF are estimated over the Industrial Era from 1750 to
1
2