A
glacial period (alternatively
glacial or
glaciation) is an interval of time (thousands of years) within an
ice age that is marked by colder temperatures and
glacier advances.
Interglacials, on the other hand, are periods of warmer climate between glacial periods. The
last glacial period ended about 15,000 years ago.<ref name="Severinghaus1999"> The
Holocene epoch is the current interglacial. A time when there are no glaciers on Earth is considered a
greenhouse climate state.