(UTC)

 Solar intensity due to proximity  
Ratio between Aphelion and Perihelion: Axial tilt comparison still needed

Request confirmation of math

There is some effect of the distance between the sun and the earth on the radiant energy reaching the earth. There is some measure of heating northern latitudes up in their winter, up to a maximum at Jan 3, and heating southern latitudes up in their summer. Thus, the winters in northern latitudes (all other variables such as warming by ocean currents, etc, removed from consideration), are relatively more mild, and the summers in southern latitudes (variables removed), relatively more extreme. However, the ratio of the aphelion (furthest distance) to the perihelion (nearest) is only 1.033988391 . So, a difference of 3.4%.

Then to calculate what that does to the total radiant energy: Inverse-square law says, "the radiation passing through any unit area is inversely proportional to the square of the distance from the point source" Received light quadruples as the distance halves.

So 

E sun energy stays the same so is 1, solving for intensity I, d is distance, using perihelion distance as 1, d (aphelion) = 1.033988391 and d2 = 1.069131994.

Multiply both sides of the equation by 1.069131994, so that I is both multiplied and divided by the same number; this cancels out, and E is now 1.069131994. E is now equal to I, as I is no longer divided by anything. I =  1.069131994.

1.069 times (aphelion intensity) = perihelion intensity. 

1 / 1.069131994 = 0.935338204, 

.935 times (perihelion intensity) = aphelion intensity.

Axial tilt total radiant energy and/or comparison with the above remains to be found
  03:50, 16 January 2011