Modeling An Ice Age
I just finished (auditing) edX and MIT's excellent course Global Warming Science and finished with some doubts about climate models. In particular, I wondered about the challenge of modeling an ice age. It looks like there has been very little progress in this area, and that in fact we know not much at all about how an ice age starts or ends. So far as I can tell, we don't really know why the rather weak changes in insolation trigger the ice age or why they end. This Scientific American note links to a study that posits one ending scenario, but that scenario still has a lot of unknown unknowns in it.
Does anyone have anything more substantial?