Aglacial period (alternativelyglacial orglaciation) is an interval of time (thousands of years) within anice age that is marked by colder temperatures andglacier advances.Interglacials, on the other hand, are periods of warmer climate between glacial periods. TheLast Glacial Period ended about 15,000 years ago.[1] TheHolocene is the current interglacial. A time with no glaciers on Earth is considered agreenhouse climate state.[2][3][4]
Glacial andinterglacial cycles as represented by atmosphericCO2, measured from ice core samples going back 800,000 years. The stage names are part of the North American and the European Alpine subdivisions. The correlation between both subdivisions is tentative.
Within theQuaternary, which started about 2.6 million yearsbefore present, there have been a number of glacials and interglacials.[5] At least eight glacial cycles have occurred in the last 740,000 years alone.[6]
The Penultimate Glacial Period (PGP) is the glacial period that occurred before theLast Glacial Period. It began about 194,000 years ago and ended 135,000 years ago, with the beginning of theEemian interglacial.[7]
The last glacial period was the most recent glacial period within theQuaternary glaciation at the end of thePleistocene, and began about 110,000 years ago and ended about 11,700 years ago.[1] The glaciations that occurred during the glacial period covered many areas of theNorthern Hemisphere and have different names, depending on their geographic distributions:Wisconsin (inNorth America),Devensian (inGreat Britain),Midlandian (inIreland),Würm (in theAlps),Weichsel (in northernCentral Europe),Dali (inEast China),Beiye (inNorth China),Taibai (inShaanxi)Luoji Shan (in southwestSichuan),Zagunao (in northwestSichuan),Tianchi (in theTian Shan)Jomolungma (in theHimalayas), andLlanquihue (inChile). The glacial advance reached theLast Glacial Maximum about 26,500BP. InEurope, the ice sheet reachedNorthern Germany. Over the last 650,000 years, there have been on average seven cycles of glacial advance and retreat.
Since orbital variations are predictable,[8] computer models that relate orbital variations to climate can predict future climate possibilities. Work byBerger and Loutre suggests that the current warm climate may last another 50,000 years.[9] The amount of heat trapping (greenhouse) gases being emitted into the Earth's oceans and its atmosphere may delay the next glacial period by an additional 50,000 years.[10][11]
^abJ. Severinghaus; E. Brook (1999). "Abrupt Climate Change at the End of the Last Glacial Period Inferred from Trapped Air in Polar Ice".Science.286 (5441):930–4.doi:10.1126/science.286.5441.930.PMID10542141.
^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.
