The Younger Dryas saw temps swing from glacial temps to interglacial temps back to glacial temps before going back up to present-day Holocene temps: https://en.

The Younger Dryas saw temps swing from glacial temps to interglacial temps back to glacial temps before going back up to present-day Holocene temps: https://en.wikipedia.org/wiki/Younger_Dryas https://en.wikipedia.org/wiki/Younger_Dryas Those kind of oscillations in climate had to be massively disruptive for all life on earth.