# ***GLOSSARIES***
**Forcing:** Human or naturally induced changes to the radiative balance at the top of the atmosphere [$W/m^2$]

**Feedback:** Is initiated by the temperature change in and of itself [$W/m^2/K$]

**Radiative forcing:** the change in net downward radiative flux at the tropopause after allowing for stratospheric temperatures to readjust to radiative equilibrium

**Effective radiative forcing:** The change in net TOA downward radiative flux after allowing atmospheric temperatures, water vapour and clouds to adjust, but with surface temperature or a portion of surface conditions unchanged

**Instantaneous radiative forcing:** Instantaneous change in net radiative flux due to an imposed change. Usually defined in terms of flux changes at TOA or climatological tropopause.

**Equilibrium climate sensitivity:** steady state change in the annual mean global surface temperature folloqing a doubling of atmospheric $CO_2$ concentration

**Transient climate response:** is the change in the global mean surface temperature, averaged over a 20-year period, centred at the time of atmospheric carbon dioxidedoubling, in a climate model simulation in which $CO_2$ increases at 1% $yr^{–1}$