You might wanna do some research into why ice ages and interglacial periods happened.

Spoiler alert: it's the composition of the air.

https://www.carbonbrief.org/explainer-how-the-rise-and-fall-of-co2-levels-influenced-the-ice-ages/#:~:text=These%20ice%20ages%20are%20triggered,age%20than%20it%20is%20today.