ice age

Definition

A period of long-term reduction in the temperature of Earth's surface and atmosphere, resulting in the presence of major polar ice sheets that reach the ocean and calve icebergs.

Etymology

Perhaps a calque of German Eiszeit.

Example Sentences

• "The earth is currently in the Late Cenozoic Ice Age, an ice age that began 33.9 million years ago with the Antarctic Ice Cap."
• "The cause of ice ages, Köppen decided, is to be found in cool summers, not brutal winters."