Now let's do a more realistic case, where we include the downward IR associated with the greenhouse effect by using the observed current climate value of 324 Wm-2 from the figure. For consistency, we'll also use the observe d value of solar radiation absorbed at the surface, 168 Wm-2. The surface energy balance is thus
sT4 = (solar radiation absorbed in the Earth system + downward IR) = (168 + 324 Wm-2)
Compute the temperature and convert to Celsius.