Younger Dryas - Video Learning - WizScience.com

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The "Younger Dryas" stadial, also referred to as the "Big Freeze", was a 1,300 year period of cold climatic conditions and drought which occurred between approximately 12,900 and 11,500 years BP in calendar years. The cause of the Younger Dryas stadial is an issue of ongoing debate. Possible scenarios include the collapse of the North American ice sheets, bringing a significant influx of freshwater to disrupt the thermohaline circulation. An alternative scenario is offered in Younger Dryas impact hypothesis, whereby a bolide collision could have caused widespread cooling through dust and aerosols entering the stratosphere. It followed the Bølling-Allerød interstadial at the end of the Pleistocene and preceded the preboreal of the early Holocene. It is named after an indicator genus, the alpine-tundra wildflower "Dryas octopetala". In Ireland, the period has been known as the "Nahanagan Stadial", while in the United Kingdom it has been called the "Loch Lomond Stadial" and most recently Greenland Stadial 1 . The Younger Dryas is also a Blytt-Sernander climate period detected from layers in north European bog peat. The Dryas stadials were cold periods which interrupted the warming trend since the Last Glacial Maximum 20,000 years ago. The Older Dryas occurred approximately 1,000 years before the Younger Dryas and lasted about 300 years. The Oldest Dryas is dated between approximately 18,000 and 15,000 BP . Based upon solid geological evidence, consisting largely of the analysis of numerous deep cores from coral reefs, variations in rates of sea level rise have been reconstucted for the early Holocene. During this period of deglacial sea level rise, three major periods of accelerated sea level rise, called "meltwater pulses", occurred. They are Meltwater pulse 1A between circa 14,600 and 14,300 calendar years ago; Meltwater pulse 1B between circa 11,400 and 11,100 calendar years ago; and Meltwater pulse 1C between 8,200 and 7,600 calendar years ago. The Younger Dryas occurred after Meltwater pulse 1A, which was a 13.5 m rise over about 290 years centered at about 14,200 calendar years ago and before Meltwater pulse 1B, which was a 7.5 m rise over about 160 years centered at about 11,000 calendar years ago. Between Meltwater pulse 1A and Meltwater pulse 1B, the Younger Dryas was a interval of a significantly reduced rate of sea level rise relative to the periods of time before and after it. For example, the analysis of cores from Tahiti coral reefs found that sea level rose at a rate of about 7.5 ± 1.1  mm/yr during the Younger Dryas. Just after the end of the Younger Dryas, the rate of sea level rise accelerated to 17.4 ± 0.4  mm/yr and just before its start, it was 12.1 ± 0.6  mm/yr. This reduction in the rate of sea level rise directly reflected a substantial reduction of the global inflow of meltwater into the world's oceans during the Younger Dryas. Wiz Science™ is "the" learning channel for children and all ages. SUBSCRIBE TODAY Disclaimer: This video is for your information only. The author or publisher does not guarantee the accuracy of the content presented in this video. USE AT YOUR OWN RISK. Background Music: "The Place Inside" by Silent Partner (royalty-free) from YouTube Audio Library. This video uses material/images from https://en.wikipedia.org/wiki/Younger+Dryas, which is released under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . To reuse/adapt the content in your own work, you must comply with the license terms.