Earth's magnetic field is maintained by the dynamo effect, and I have no doubt that this effect could sustain Earth's magnetic field for a very long ("infinite") time.
It's my understanding that the energy flow is as follows. Thermal gradients in the liquid metal and differential rotating inner iron core and inner mantle yield kinetic liquid metal energy, which results in viscous dissipation losses, and magnetic energy, which results in joule heating.
The differential rotating inner iron core and inner mantle is fueled by the conserved angular momentum of the rotating earth. The same side of our moon always faces us due to (I think) tidal locking (water tides on the moon slowly stripped its angular momentum).
Here's my question:
Can we lose the energy source from differential rotating inner iron core and inner mantle over time by losing the differential rotation?
If the answer to 1. is "yes", then will the other input energies be enough to maintain Earth's dynamo?
If the answer to 2. is "no" or "maybe", then can we compute a time estimate of how long that will take? How long will it take?
Any help is greatly appreciated!