> If we observe a cycle happening dozens of times, but assert that THIS TIME it's somehow being driven a different mechanism, certainly the onus is on us to explain conclusively how & why the previous mechanism stopped and a new mechanism took over.
Sure, that is very true.
And the answer is the following:
The evidence is geological, that when humans mined coal, there were no coal shafts and evidence of previous mining and combustion from 120,000 years ago. Instead, the isotopic and geological analysis shows that the carbon which is being emitted now is from human activities which didn't exist 120,000 years ago.
Something new is definitely happening: human mining & combustion.