As ozark1 says, it is much less significant. I guess the question is how much?

Do they have a reference?

PS: I just googled "kate bradshaw"+"discovering science" and nothing came up. Is there another title I should use?

PSS: Here's another reference that appears to say something similar, but has only the abstract.

PSSS: Ah, that references Kelvin's assistant Perry. Here's another column that says essentially what you're saying, that it is convection that is the issue. However, it points out that Perry's model has an interior core that goes to within 30 miles of the interior, and it is well-stirred. That quite a bit away from the current understanding too. The column he is correcting.

PSSSS: Don Anderson article on the Energetics of the Earth. Weirdly, he seems to be saying that convection doesn't pipe a lot of the heat to the surface, from the core.

Anyway, good question Eroica. I assume ozark1 is next?