To make a ‘Snowball Earth,’ sci-fi moves fast. Geology is far slower

Earth experienced at least five ice ages, including severe "Snowball Earth" events 720-635 million years ago when glaciers covered the planet pole-to-pole due to slow geological processes like tectonic shifts and reduced atmospheric carbon dioxide. Science fiction stories accelerate these natural freezing mechanisms for dramatic effect, compressing timescales from geological eras to mere weeks or years.