A World Without Air

Like Don Quixote suffering a coffee overdose, once again I mount my steed, take up my lance, and go tilting at windmills.

Here’s a thought experiment. Consider the Earth with no atmosphere and with the same surface albedo of 12.5% that it has now. How warm would it be?

In this condition, because there is no atmosphere, there are no heat losses from the surface by sensible or latent heat. For the same reason, there’s no reduction in incoming solar power as a result of reflection from clouds or solar radiation absorbed by the atmosphere. Solar radiation absorbed at the surface is radiated straight back to space. So we can calculate the temperature directly from the absorbed radiation using the Stefan-Boltzmann equation. This equation relates watts per square meter of surface radiation to the corresponding temperature of the radiating surface. I used the S/B equation with the average emissivity of the Earth, which is ~ 0.98, to calculate the surface temperature. All values are in watts per square meter (abbreviated variously as W/m2 or W/m²).

Minus two degrees C. What you might call totally chill. Just below freezing, in fact.

Now, over millions of years, let’s slowly add in an atmosphere and when it matches the modern atmosphere in all respects, let it percolate for another few million years.