The Ice Age By: Sue Peterson What is an ice age?

An ice age is a time period when the temperature of the Earth’s surface and atmosphere is greatly reduced so that there is a presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers in the southern and northern hemispheres. Within this time period, individual pulses of cold climate are considered “glacial periods” and warm intermittent periods are called “interglacial periods”. Using the definition of glacial and interglacial periods, geologists classify the present condition of the world as an ice age that began 2.6 million years ago because the Greenland and Antarctic ice sheets still exist.