If you want to get technical, we’re still in an ice age, one that has lasted millions of years—we’re just in an interglacial period at the moment. Anyway, at the time of the Quaternary extinction, the warming of the planet and retreating glaciers put many species at risk. Large animals that had evolved for cold weather died out, and those that survived fell prey to humans invading their environment. It’s hard to imagine the scale of this climate change. The ice sheets that covered much of Asia, Europe, and North America stopped advancing and started retreating.
