For most of its history until fairly recent times the general pattern for Earth was to be hot with no permanent ice anywhere. The current ice age-ice epoch really-started about forty million years ago, and has ranged from murderously bad to not bad at all.
Throughout much of Earth's history, the planet was predominantly warm, lacking permanent ice formations. Only in the last forty million years has an ice age evolved, introducing significant climatic variations that have led to periods of severe cold and warmer intervals.
Bill Bryson's "A Short History of Nearly Everything" highlights this transition, emphasizing how the current ice epoch has fluctuated significantly in severity. This prompts reflection on how climate has dramatically shifted over geological time scales, impacting the natural world and life on Earth.
