The above chart which shows that volcanic activity increases during cool periods in Earth’s climate was something I first saw around 2007. I got the graph from “Ice Age Now” where a commenter had this to say:
as a sound engineer, i notice the oscilations of these cycles, or waves….notice how they come closer togheter, as a tone pitched up…
The first thing to note is that climate is chaotic in the mathematical sense. In chaos theory the periods getting smaller is referred to as “period doubling”. It presages a move to a new strange attractor. It is possible that the new strange attractor is an end to the current interglacial. A new full blown ice age.