Anyone who has spent a winter in northern Maine can tell you the Earth is not pumping up great amounts of heat from the interior. Since the crust is thinnest under the ocean floor and much of the interior heat that does make it to the surface comes via magma released in deep ocean ridges and vents, I would think that it would be the oceans that would exhibit changes if the interior were cold. Probably ocean currents would change and surface weather patterns would change as a result. Maybe take the drastic weather changes caused by El Nino and multiply that by ten or so.
I wouldn’t think the interior being cold would be a greater factor than greenhouse gases on global temperature. Since some theories of ice ages involve ocean current changes rather than total heat balance it could be possible that the interior being cool could cause changes as drastic as an ice age.
I doubt that Lord Kelvin had the foggiest idea of the rate of transfer of heat from the interior into space. Modern science probably can’t calculate it within a factor of two. It might be possible that we could still have a molten core without accounting for radioactivity at all.
There would be no imediate impact on climate. The current surface temperature of the Earth is basically a product of incoming solar radiation and the heat-trapping effects of an atmosphere with a certain amount of greenhouse gases in it (primarily carbon dioxide).
Now, over very long time scales (tens of millions of years) the climate would almost certainly deteriorate. That’s because plate tectonics, which would no longer be operating, plays an important role in returning carbon dioxide to the atmosphere. Carbon buried in rocks and sediments would normally be recycled during subduction, and CO2 gas released during volcanic eruptions (this is part of the carbon cycle that controls climate on this world). No plate tectonics=no carbon recycling=no CO2 to help keep the atmospheric greenhouse effect intact. Of course, our descendants could try burning fossil fuels like mad, or deliberately release CFC’s and HCFC’s into the atmosphere, but those acts would cause other problems, and would probably only prolong the agony.
Back to the present. An immediate effect of the core being cold and solid tomorrow would be the collapse of the Earth’s magnetic field & the Van Allen belts. That means decreased shielding from cosmic rays & solar wind… you won’t instantly get cancer and die, but cancer rates would probably go up. Plus there’d be communications havoc with the amount of interference going through the roof - solar flares can cause significant problems now, just imagine what it would be like without the shielding effects of the magnetic field.
[note: the above descriptions are gross simplifications to avoid an overly lengthy post]
I think that David Innes is a solar physicist, and Abner Perry is an oceanographer… what in particular did they say? I’m not familiar with their writings.
I don’t know why it’s so hot… but I do know the Earth’s core is solid because of all the weight around it. And the magma comes from the mantle which is (I’m pretty sure) 30000 km deep. I doubt it will empty anytime soon.
