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.[1] The Holocene is the current interglacial. A time with no glaciers on Earth is considered a greenhouse climate state.[2][3][4]
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^Christopher M. Fedo; Grant M. Young; H. Wayne Nesbitt (1997). "Paleoclimatic control on the composition of the Paleoproterozoic Serpent Formation, Huronian Supergroup, Canada: a greenhouse to icehouse transition". Precambrian Research. 86 (3–4). Elsevier: 201. Bibcode:1997PreR...86..201F. doi:10.1016/S0301-9268(97)00049-1.
^Miriam E. Katz; Kenneth G. Miller; James D. Wright; Bridget S. Wade; James V. Browning; Benjamin S. Cramer; Yair Rosenthal (2008). "Stepwise transition from the Eocene greenhouse to the Oligocene icehouse". Nature Geoscience. 1 (5). Nature: 329. Bibcode:2008NatGe...1..329K. doi:10.1038/ngeo179.