Effect of carbon dioxide on past ice ages

Question

If anthropogenically produced carbon dioxide has prevented the earth from entering a new ice age, why were past ice ages not prevented from occuring since carbon dioxide levels were much higher in the past than they are now?

Is global warming preventing the next ice age?

Human emissions will delay next ice age by 50,000 years, study says

Human-Made Climate Change Has Suppressed The Next Ice Age, Researchers Say

Answer 1

Carbon dioxide levels were much higher in the very distant past, but more recently they've been lower. It's been below current levels since about 3 million years ago, which coincides with the present ice age. When CO$_2$ levels were much higher tens of millions of years ago, global temperatures were also much higher (same source).