An average square meter of the Earth receives on average
341 watts of solar power. Of this, about 161 watts is absorbed at the surface.
In comparison, the average geothermal heat flux is about
.09 watts per square meter, 4000 times smaller and basically negligible for the purposes of evaluating Earth's surface climate.
However, the incoming solar energy is returned to space as infrared energy emitted from the ground. The balance between these two shifts over the seasons, but over the whole year they cancel out almost exactly.
The net result is that the seasonal cycle cause the ground to heat and cool in the
upper few meters of the ground, but below that its impact is almost zero.
