You aroused my curiosity enough to do some Googling. Three search observations I recorded:
So the question is: how much does the Earth's internal (core) heat contribute to the warmth on the surface of the Earth?
And a corollary question: if our inner core's heat should suddenly die, could humans survive using only the Sun's heat?
At such time that the Earth’s core goes cold, the magnetic field that protects us from solar radiation also goes away, so it may not matter if the sun is enough, as it may be too much.
“The temperature of the molten inner core of Earth is 10,800 degrees F. “ Pffffttttt. Algore said it was millions of degrees. Case closed!
“So the question is: how much does the Earth’s internal (core) heat contribute to the warmth on the surface of the Earth?”
It’s a smaller factor than the sun’s heat by far, but it does make some not insignificant contribution.
“if our inner core’s heat should suddenly die, could humans survive using only the Sun’s heat?”
We probably could, but any interruption in the balance and feedback cycles could be far ranging, because each element has effects on the other elements in the system, and we definitely do not understand all of the interdependencies of the system in great detail.
The real problem if the core “went out” is that we would probably no longer have a global magnetic field protecting the earth, since that seems to be generated only by an active molten core. No magnetic field would mean very little protection from the solar wind, so more of our upper atmosphere would be stripped off, and more UV radiation would be bombarding the surface. That’s a pretty deadly combination that would probably lead, in time, to the Earth looking a lot more like Mars.
Well, if you dig down a short depth, like 20 feet, it's a constant 55 degrees.
Depending on where you are, the "frost line" varies from 3-10 feet.
What, is the molten core starting to freeze up?