"the climate of this planet oscillates between periods of approximately  30 years of warming followed by approximately 30 years of cooling.
"the climate of this planet oscillates between periods of approximately  30 years of warming followed by approximately 30 years of cooling.
ice age:0
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.