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From: Free Thinking Doggie
Interesting section... 'Next glacial period Further information: Milankovitch cycles, Past sea level, Climate change, and Human impact on the environment The warming trend following the Last Glacial Maximum, since about 20,000 years ago, has resulted in a sea level rise by about 121 metres (397 ft). This warming trend subsided about 6,000 years ago, and sea level has been comparatively stable since the Neolithic. The present interglacial period (the Holocene climatic optimum) has been stable and warm compared to the preceding ones, which were interrupted by numerous cold spells lasting hundreds of years. This stability might have allowed the Neolithic Revolution and by extension human civilization.[48] Based on orbital models, the cooling trend initiated about 6,000 years ago will continue for another 23,000 years.[49] Slight changes in the Earth's orbital parameters may, however, indicate that, even without any human contribution, there will not be another glacial period for the next 50,000 years.[50] It is possible that the current cooling trend might be interrupted by an interstadial phase (a warmer period) in about 60,000 years, with the next glacial maximum reached only in about 100,000 years.[51] Based on past estimates for interglacial durations of about 10,000 years, in the 1970s there was some concern that the next glacial period would be imminent. However, slight changes in the eccentricity of Earth's orbit around the Sun suggest a lengthy interglacial period lasting about another 50,000 years.[52] Other models, based on periodic variations in solar output, give a different projection of the start of the next glacial period at around 10,000 years from now.[53] Additionally, human impact is now seen as possibly extending what would already be an unusually long warm period. Projection of the timeline for the next glacial maximum depend crucially on the amount of CO 2 in the atmosphere. Models assuming increased CO 2 levels at 750 parts per million (ppm current levels are at 417 ppm[54]) have estimated the persistence of the current interglacial period for another 50,000 years.[55] However, more recent studies concluded that the amount of heat trapping gases emitted into Earth's oceans and atmosphere will prevent the next glacial (ice age), which otherwise would begin in around 50,000 years, and likely more glacial cycles.[56][57]

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