Planck Feedback. The most fundamental feedback effect is simply that when the Earth's
surface gets warmer, it loses heat faster, thereby reducing the increase in temperature.
“It is like pumping air into a tyre with a puncture: the harder you pump the faster the air
escapes.” –Clive Best
The simplest and easiest to quantify component of that effect is the radiative component,
called “Planck feedback.” Radiative emissions from a warm body are
proportional to
the 4th power of the body's absolute temperature (temperature in Kelvin), according to the Stefan-Boltzmann law:
E = ε σ T4
where:
epsilon ε is emissivity, [0..1] (function of frequency, unless perfect grey-body)
sigma σ is the Stefan-Boltzmann constant, 5.670374419E-8 W/m2K4
temperature T is in Kelvin
E = radiative emission in W/m2
It is calculated that a uniform global temperature increase of
1°C would increase radiant heat loss from the surface of the Earth by about 1.4% (variously estimated to be
3.1 to 3.7 W/m², or 3.1 to 3.3 W/m² in the CMIP5 models,
or 3.0 to 3.4 W/m² in AR6 §7.4.2.1
— it's complicated).
warmer surface → more rapid radiative heat loss → cooler surface
However, Koll & Cronin (2018) report that...