Which begs the question--where did the ENERGY come from?? There are only two sources of energy available---radioactive decay from isotopes (which, since they are a constantly decreasing fraction of the earth's mass, cannot contribute), and the sun. We already have evidence to account for changes in the photonic contribution of solar output to the prehistoric geological record (various isotopes from the solar wind)--so exactly how is this extra energy "coupled" into the earth from the sun???
My own thought is that there is an electromagnetic effect related the the sun's magnetic field. In current time, we have measurements showing that the sun's magnetic field has DOUBLED in historic time. How does that doubling effect the earth?? We KNOW from the laws of physics that ANY conductor moving in a magnetic field generates an electric current flow. The earth has LOTS of conductive systems (magma, the oceans--to pick what are probably the two largest), so there MUST be increased ohmic heating happening. How big is it?? Could THAT be the "missing link" in understanding what drives ice ages??
Lots of questions, but, thus far, I've been able to find ZERO answers. As far as I've been able to find out, this question has never been raised in the context of "global warming" so-called "science".
More directly, I go with undersea volcanism. They still really don’t know the seafloor, not much data on energy leaking out of the mantle.
Flip that: The earth’s magnetic poles - possibly/probably beginning a switch of north pole - south pole directions - is rapidly decreasing since the early 1800’s, and is rapidly moving across the Ar tic towards Siberia by several hundreds of miles. Well away from its historic position in south Hudson Bay. Previous movements in recorded decades have only been slow circles across a few dozen miles.
Change magnetic field intensity and you see a tremendous increase in cosmic ray reception (regardless of cosmic ray source intensity.) Also, you see the result - as you pointed out - in increased solar reception. Lower mag fields = less shielding = more solar reception.
Regardless of sunspot activity - which is also increasing!