Earth’s Core Has Stopped and May Be Reversing Direction, Study Says

This is so extraordinary as to be totally unbelievable.

If the inner core is not presently rotating, surely we'd see massive disturbances in the geomagnetic field?

The inner core is also enormous. The amount of energy required to change its direction would be incredible, especially on the scale of decades. It'd be like reversing the rotation of the moon in under a century. Absolutely ludicrous amounts of energy.

I'm not a geophysicist, so I'm totally making things up, but surely applying that much energy to move the inner core would result in a massive decrease in overall magnetic field strength? And how can the inner core rotate counter to the rest of the planet? The energy lost to turbulence at the inner/outer core boundary would be immense!

An inner core spinning opposite to the outer core would create two inverse magnetic fields, strongly weakening the overall field produced by the outer core. The opposite rotating magnetic fields would also burn a ton of energy fighting each other, sending eddy currents through any metallic minerals inside the field.

Again, I'm not a physicist, but none of this makes any sense. The energies are just too huge for this to happen without massive visible effects.

I'd need to see a lot more numbers before I'll give this any credibility.

Since the linked paper refers to "differential rotation" when it says that the core has "stopped" they actually mean it has synched up with the mantle (in the heliocentric frame, I guess), is that correct?

That darned movie again!