Ice Age

An ice age is a long period of reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Individual pulses of cold climate are termed "glacial periods" (or, alternatively, "glacials", "glaciations", "glacial stages", "stadials", "stades", or colloquially, "ice ages"), and intermittent warm periods are called "interglacials" or "interstadials".

In common usage, "Ice Age" most commonly refers to the Pleistocene Epoch, which lasted from about 2,588,000 to 11,700 years ago. It was the first such natural phenomenon since the evolution of humans.

Ice Age in "The Mrem Go West"
The end of the Ice Age caused a cultural upheaval for the world's two sentient species, as the mammalian Mrem were forced out of their polar homeland, to the warmer climate inhabited by the reptilian Liskash.