[lazide]

The outer core is 2,890 KM (~ 1800 miles) below the earths crust, and has the mantle in the way. The crust itself is only 30KM thick. [https://phys.org/news/2017-02-journey-center-earth.html] The crust is basically a thin layer of slag on top of a giant ball of molten everything.

Even at million+ year timescales, I can’t see any way the temperature of the upper crust could matter to the core at all - even if the crust was at absolute zero.

Dirt insulates relatively well, and the amount of thermal mass present is mindboggling.

[thehappypm]

if you lived in the Earth’s core (~6000k) the surface (~300k) would be a rounding error above absolute zero anyway

[conditionnumber]

> would be a rounding error above absolute zero anyway

Kind of joking: unless there are nonlinear effects near 300K? Fig 4 [1] seems to suggest that the thermal diffusivity of the mantle grows very fast as temperature declines past 300K... but the data stop at 200K.

Reason for initial comment: we could probably set up a spherical heat equation to guess how crust cooling would change heat conduction at the outer core. But I have absolutely no idea how to reason about changes in heat conduction affecting the convection dynamics that generate the field. I was silently hoping for one of the domain experts lurking this forum to see it and share wisdom. (But overall it was a silly question, I know).

[1] https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200...