Glaciers have existed on Earth for at least 60 million years, a period stretching back almost to the time of the dinosaurs. New research pushed the date when the planet was last glacier-free back to at least 26 million years.
It may not feel like it, but Earth is currently in an “icehouse phase”-relative to its long-term geological history. Conditions at present are cold enough to support permanent ice sheets at both poles and more than 200,000 glaciers at high and low elevations across the planet. This has not always been so.
In the geological past Earth was much warmer and glaciers were almost certainly absent from the very coldest and highest mountains. This is best demonstrated during the Late Cretaceous period (100 million to 66 million years ago) when dinosaurs existed and the climate was up to 20C warmer than today. Then, the “sub-tropical” forests present today in Mexico or India covered most of Antarctica.
https://phys.org/news/2022-12-glaciers-earth-million-yearsfar-longer.html