The simplest model discussion so far occupies a few posts:
- The Simplest Meaningful Climate Model
- Building the Simplest Meaningful Climate Model
- Analyzing the Simplest Meaningful Climate Model
- (From Atmoz blog) The Simplest Climate Model: Oblate Spheroid Edition
Atmoz found about a 0.07 degree C difference for the earth's temperature for oblate (and at equinox) vs. perfect sphere. Probably something about that size too for the solstices too, though we need the computation to be sure.
Here I've used an albedo of 0.30 and solar constant of 1367 W/m^2. Atmoz preferred 0.29 and 1366, respectively. Thanks to our looking into the sensitivity of the model in the analysis note, we know that this amounts to only about a 1 K difference in computing the earth's temperature. That suggests a few things. One is, the surface temperature averaging 288 K is unlikely to be explainable by modest changes from the values we used. Another is that it'd be a good idea to chase down some good sources on what values should be used, exactly. Or that at least we'll want to find out what the levels of uncertainty are about these observable quantities.