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Modified 3 years, 1 month ago. The thinking is that as the ice age ended and the enormous Laurentide ice sheet atop . addEvent(form_to_submit, 'submit', form_submit); This process is well documented in Iceland, when volcanic activity under glaciers causes rapid melting of ice, causing ice dam bursts. I'd love for someone to weigh in and point out anything I have missed. The late Pleistocene cold glacial climate that built immense . Post-16 Save my name, email, and website in this browser for the next time I comment. Conference var remove_tooltips = function() { var addEvent = function(element, event, func) { ice stream The change to glacial conditions at the onset of the Younger Dryas in the higher latitudes of the Northern Hemisphere, between 12,900 and 11,500calibrated yearsBP, has been argued to have been quite abrupt. Proxy data recorded in the stalagmite indicate that more than 550calibrated years were needed for Younger Dryas drought conditions to reach their full extent in the region and about 450calibrated years to return to pre-Younger Dryas levels after it ended.[41]. Zoom in to an area with detailed moraine ridges, like the terminal moraines in the Lake District. } else { [101] Finally, research by Lohe and others in western Norway has reported a sea-level low-stand at 13,640calibrated years ago and a subsequent Younger Dryas transgression starting at 13,080calibrated years ago. })(); All Rights Reserved The Human Origin Project. A cluster of comet fragments believed to have hit Earth nearly 13,000 years ago may have shaped the origins of human civilization, a controversial theory suggests. dating [45] In western North America, its effects were less intense than in Europe or northeast North America;[46] however, evidence of a glacial re-advance[47] indicates that Younger Dryas cooling occurred in the Pacific Northwest. [114] The Laacher See volcanic eruption hypothesis has likewise been ruled out because precise dating demonstrates that it erupted more than 200 years before the Younger Dryas onset. BP) in the Luka profile; this may have been related to the . - warm water becomes cooler and increases its salinity by exchanging heat with the cooler air. It doesnt explain how the much, much larger Laurentide Ice sheet vanished in a geological blink of an eye. Environmental Science, Geography. Noah and the Younger Dryas Did an asteroid cause the flood mentioned in the OT. } else if (input.type == 'radio' || input.type == 'checkbox') { tooltip.className = '_error'; Such an event would fit with a single flood due to a large amount of energy dispersed. (2018a) reconstructed the ice limits and the extent of ice-dammed lakes. The Younger Dryas impact hypothesis posits that fragments of a large (more than 4 KM in diameter), disintegrating asteroid, or comet, struck North America, South . resize_tooltip(tooltip) : false; selected = false; The temperatures dropped massively entering into a near-glacial period where it was cold and windy and . "); } var oldFunc = element['on' + event]; elems[i].className = elems[i].className + ' _has_error'; . }; Ask the students to think about the different kinds of glacial landysystems they can find in the Younger Dryas of Britain. div.innerHTML = html; ", "Why won't this debate about an ancient cold snap die? var tooltip = null, value = elem.value, no_error = true; These were carved out by Missoula Flood waters. Drift limits can be used alongside moraines to demarcate the maximum extent of the ice limits. The Antarctic Cold Reversal appears to have started a thousand years before the Younger Dryas and has no clearly defined start or end; Peter Huybers has argued that there is a fair confidence in the absence of the Younger Dryas in Antarctica, New Zealand and parts of Oceania. for (var i = 0; i < elems.length; i++) { if (validate_form()) { Sea levels were 400ft lower that exposed millions of miles of land today covered in sea. for (var i = 0; i < elem.options.length; i++) { Despite this, Bretz continued to build evidence for the single flood he proposed. During the 20th century, Bretz painstakingly built evidence on the ground with little access to helicopter or satellite technology. Believers set the date of the destruction of Atlantis at 11,550 BP (9,600 BC). window._show_error = function(id, message, html) { This vegetation map showing the eastern USA during the period 28,000-25,000 14C y.a. [98][101], Possible evidence of short-term sea level changes has been reported for the beginning of the Younger Dryas. I wrote and developed the AntarcticGlaciers.org website as part of an ongoing commitment to outreach, education and research impact. "); Because significant warming preceded this dramatic event palaeoclimatologists

var getUrlParam = function(name) { The presence of a distinct cold period at the end of the LGM interval has been known for a long time. Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean. One of the biggest mysteries is what caused the prehistoric North American ice sheet to disappear. elem.className = elem.className + ' _has_error'; The first stage which occurred at the onset of the Younger Dryas around 12,800 years ago marked the start of a humungous flood followed by extreme global cooling. Many are still observable today. [19] Thermally fractionated nitrogen and argon isotope data from Greenland ice core GISP2 indicate that its summit was around 15C (27F) colder during the Younger Dryas[17][20] than today. The Younger Dryas return to a cold, glacial climate was first considered to be a regional event restricted to Europe, but later studies have shown that it was a world-wide event. The lack of geological evidence for such an event,[103] stimulated further exploration that has now identified a pathway along the Mackenzie River that would have spilled fresh water into the Arctic and thence into the Atlantic. The Younger Dryas Impact dates to the beginning of the Younger Dryas, ~12,800 years ago. WAIS First, the plotting of data by Bard and others suggests a small drop, less than 6m, in sea level near the onset of the Younger Dryas. Some scientists believe this was caused when the North American ice sheet receded past the St Laurence river causing all of the fresh water melt from the glaciers to flow up the St Laurence into the North . allInputs[i].dataset.name = allInputs[i].name; [87] An increase of pine pollen indicates cooler winters within the central Cascades. var create_tooltip = function(elem, text) { ", "Prolonged heavy snowfall during the Younger Dryas", "An ice-climate oscillatory framework for Dansgaard-Oeschger cycles", "The anatomy of past abrupt warmings recorded in Greenland ice", "Rain driven by receding ice sheets as a cause of past climate change", "Evidence for a Solar flare cause of the Pleistocene mass extinction", "Did a massive Solar proton event fry the Earth? var allInputs = form_to_submit.querySelectorAll('input, select, textarea'), tooltips = [], submitted = false;

It is thought that the comet strike known as the Younger Dryas impact also wiped out many large animal species and ushered in a mini ice age that lasted more than 1,000 years. } antarctica The geomorphological evidence has been organised into a series of shapefiles, each containing a different landform type. An example of this is the Sajama ice core (Bolivia), for which the timing of the DCR has been pinned to that of the GISP2 ice core record (central Greenland). window._show_thank_you = function(id, message, trackcmp_url) { selected = true; if (!no_error) { Studies now reveal that Western Canada was ice-free some 14 000 years ago. The glacial geomorphology of the Loch Lomond (Younger Dryas) Stadial in Britain: a review, Glacial landsystems, retreat dynamics and controls on Loch Lomond Stadial (Younger Dryas) glaciation in Britain. tooltip = create_tooltip(elem, "Enter a valid date. } The change was relatively sudden, taking place in decades, and it resulted in a decline of temperatures in Greenland by 4~10C (7.2~18F),[4] and advances of glaciers and drier conditions over much of the temperate Northern Hemisphere. Trimlines form at the ice surface in valleys; the area below the trimline was covered in glacier ice and wasa subjected to glacial erosion. One geologist named J Harlen Bretz proposed a catastrophic single flood that wiped the majority of glacial ice. if (elem.type != 'checkbox') elem.className = elem.className.replace(/ ?_has_error ?/g, ''); The Younger Dryas The Younger Dryas is one of the most well-known examples of abrupt change. };

sea ice ", "Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation", "Study confirms mechanism for current shutdowns, European cooling", "What If the Conveyor Were to Shut Down? For example, paleoenvironmental analysis of sediment cores from Lake Suigetsu in Japan found the Younger Dryas temperature decline of 24C between 12,300 and 11,250varve (calibrated) yearsBP, instead of about 12,900calibrated yearsBP in the North Atlantic region. if (element.addEventListener) { }; } A great blanket of ice called the Cordilleran Ice Sheet covered most of Canadian North America, dipping down into parts of the U.S. As the ice melted, it formed lakes like Lake Missoula where the water was held in by a 2,000-foot wall of ice. } [60] During the Younger Dryas, the Southeastern United States was warmer and wetter than the region had been during the Pleistocene[61][53][62] because of trapped heat from the Caribbean within the North Atlantic Gyre caused by a weakened Atlantic meridional overturning circulation (AMOC). In fitting the sea level curve, the shallowest A. palmata were assumed to be living closer to the sea surface than those plotting deeper and are used as guide points to generate a "best fit" curve. Partin, J.W., T.M. You can view the entire geomorphological database in this PDF map (Bickerdike et al., 2016). r = true; However, other scientific arguments support the idea of a single flood. The Younger Dryas Impact Hypothesis is highly controversial. var serialized = _form_serialize(document.getElementById('_form_1_')); Meltwater channels can therefore help to determine the location of the ice margin, and also determine the nature and style of glaciation. Pine-Island tooltips[i].tip.parentNode.removeChild(tooltips[i].tip); remove_tooltip(elem) : false; Meltwater channels were formed by the passage of water and can form under the glacier (subglacial), in front of the glacier (proglacial) or on the valley side, between the glacier and any valley sides (ice-marginal). } decodeURIComponent(results[1]) : false; The Younger Dryas period has been documented as one of the most turbulent stages in prehistory. [Measurements] firmly date the [Laacher See eruption] to 13,006 9calibrated years before present (BP; taken as AD1950), which is more than a century earlier than previously accepted. [98][99][100] Finally, not only did the Younger Dryas postdate both all of meltwater pulse1A and predate all of meltwater pulse1B, it was a period of significantly-reduced rate of sea level rise relative to the periods of time immediately before and after it. Photo: Tom Foster. A. Carlson. tooltips = []; } else { Climatic forcing moved cold air into the northern portion of the American interior, much as it did the Northeast. The drastic change in vegetation is typically interpreted to be an effect of a sudden decrease in (annual) temperature, unfavorable for the forest vegetation that had been spreading northward rapidly. }); ice flow Glaciers also grew in Snowdonia, the Brecon Beacons, the Lake District, and on the Hebridean Islands. window._load_script = function(url, callback) { if (old_error) old_error.parentNode.removeChild(old_error); The huge problem facing scientists is to explain where all that mid planet ice went. } else if (elem.type =='checkbox') { Contemporaneous changes of climate and environment in more southerly regions were variably expressed. err.push("Checking %s is required".replace("%s", elems[i].value)); }; document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. tooltip.appendChild(inner); 3) would open a corridor from Lake Agassiz to the Arctic Ocean during the . [12] The Older Dryas, in turn, was preceded by another warmer stage, the Blling oscillation, that separated it from a third and even older stadial, often known as the Oldest Dryas. What would the proposed advanced civilization be like in the Young Dryas? You can view the Metadata by clicking on the three little dots to the right of each layer in the Layer List. }; Location map showing 53 YD boundary sites. Across this huge "fingerprint" spanning North America, Central America, parts of South America, most of Europe and parts of the Middle East as well, the tell-tale traces of multiple . This will bring up the Attribute Table for all the layers. You can turn layers on and off using Layer List, and fiddle with their transparency and other settings. match[2] : null; Africa (map in preparation). However, this same shift in the radiocarbon signal antedates the start of Younger Dryas at Lake Suigetsu by a few hundred years. Dryas octopetala. extinction episode wiping the Woolly mammoths, http://science.sciencemag.org/content/358/6364/781, http://sp.lyellcollection.org/content/143/1/171, https://pubs.er.usgs.gov/publication/70041337, How Earth Periods and Ice Ages Guide Climate Change, The Evidence for the Younger Dryas Impact Hypothesis, The Younger Dryas Event and the Prehistoric Period Extinction, How to Practice Taoism with a 5-Step Color Meditation, 20 Ways to Heal Pineal Gland Calcification & Open the Third Eye, HOP Podcast #23: Walter Cruttended on Precession,Binary Star and Yuga Cycles, Ancient wisdom merged with modern science. The most accepted theory of how the North American glaciers melted is the ice-dam burst theory. Teller J.T., Yang Z., 2010. var needs_validate = function(el) { Share this post. ], where present represents 1950 C.E.) The Younger Dryas, which occurred circa 12,900 to 11,700 years BP, was a return to glacial conditions which temporarily reversed the gradual climatic warming after the Last Glacial Maximum (LGM), which lasted from circa 27,000 to 20,000 years BP. author } else { if (callback) { Zoom to a new area and once the map has loaded, click the little black tab at the base of the screen. View 2 excerpts, cites background. [53][66] In the north, the Laurentide Ice Sheet re-advanced during the Younger Dryas, depositing a moraine from west Lake Superior to southeast Quebec. Mar 1. window._old_serialize = null; return new_tooltip; [91] Pollen record from the Siskiyou Mountains suggests a lag in timing of the Younger Dryas, indicating a greater influence of warmer Pacific conditions on that range,[92] but the pollen record is less chronologically constrained than the aforementioned speleothem record. The data were compiled in a series of papers by Bickerdike et al. No, the dates are all wrong for that. if (window.location.search.search("excludeform") !== -1) return false; Do you think the Ice-Dam Burst theory explains the loss of the North American Ice Sheet? However, new evidence has revealed that the collapse of prehistoric glaciers occurred in as little as 4000 years. Thousands of square miles of vegetation were completely washed away as well as intense amounts of soil and sediment. More information: Large Pt anomaly in the Greenland ice core points to a cataclysm at the onset of Younger Dryas, PNAS, Published online before print July 22, 2013, DOI: 10.1073/pnas.1303924110 . }; Blue is cooling, red warming (Shakun and Carlson 2010). Further climatic deterioration is thought to have brought about cereal cultivation. no_error = false; Graham Hancock is an audacious autodidact who believes that long before ancient Mesopotamia, Babylonia and Egypt there existed an even more glorious civilization. The violent weather patterns of the Younger Dryas were discovered through the Greenland Ice Cores in the 1990s. SWW (function(el) { if (typeof(trackcmp_url) != 'undefined' && trackcmp_url) { [108][109], There are several hypotheses for the cause of the increased flux of meltwater that led to the Younger Dryas onset. true : no_error = false; The glacial geomorphology of the Loch Lomond Stadial in Britain: a map and geographic information system resource of published evidence. [52] The effects of sudden cooling in the North Atlantic had strong regional effects in North America, with some areas experiencing more abrupt changes than others. var radios = form_to_submit.elements[el.name]; This included the Columbia Basin, an area that featured largely in Bretzs proposal for catastrophic flooding. There are a number of icons in the left hand corner. [93], The Younger Dryas is often linked to the Neolithic Revolution, with the adoption of agriculture in the Levant. This event is believed to have caused widespread destruction and resulted in significant changes . Banner, K. Lin, H.-M. Hu, and F.W Taylor (2014), Atlantic meridional overturning circulation, Puerto Princesa Subterranean River National Park, Oregon Caves National Monument and Preserve, shutdown of the North Atlantic "Conveyor", Atlantic Meridional Overturning Circulation, "Mapping Post-Glacial expansions: The Peopling of Southwest Asia", "A new Greenland ice core chronology for the last glacial termination", "Mechanisms of abrupt climate change of the last glacial period", "Greenland temperature response to climate forcing during the last deglaciation", "Younger Dryas: A data to model comparison to constrain the strength of the overturning circulation", "Synchronized terrestrial-atmospheric deglacial records around the North Atlantic", "Det senglacie ler i Allerd tegelvrksgrav", 10.1002/(SICI)1099-1417(199807/08)13:4<283::AID-JQS386>3.0.CO;2-A, "Big freeze: Earth could plunge into sudden ice age", "Three amphi-Atlantic century-scale cold events during the Blling-Allerd warm period", "A Pliocene-Pleistocene stack of 57 globally distributed benthic 18O records", "Pleistocene glacial terminations triggered by synchronous changes in Southern and Northern Hemisphere insolation: The insolation canon hypothesis", "The Holocene-Younger Dryas transition recorded at Summit, Greenland", "Revisions and extension of the Hohenheim oak and pine chronologies: New evidence about the timing of the Younger Dryas/Preboreal transition", "Formal definition and dating of the GSSP, etc", "Climate Change 2001: The Scientific Basis", 10.1002/1099-1417(200005)15:4<377::AID-JQS542>3.0.CO;2-L, Palaeogeography, Palaeoclimatology, Palaeoecology, "Pleistocene megafaunal collapse, novel plant communities, and enhanced fire regimes in North America", "Evidence for a late glacial advance near the beginning of the Younger Dryas in western New York State: An event postdating the record for local Laurentide ice sheet recession", 10.1130/0091-7613(2002)030<0971:rawvrt>2.0.co;2, "Abrupt climate oscillations during the last deglaciation in central North America", 10.1890/0012-9658(2001)082[3346:daolqv]2.0.co;2, "A record of post-glacial moraine deposition and tephra stratigraphy from Otokomi Lake, Rose Basin, Glacier National Park, Montana", 10.1130/0091-7613(1994)022<0439:AOTCAI>2.3.CO;2, 10.1130/0091-7613(2000)28<51:RROATV>2.0.CO;2, "High-resolution climatic evolution of coastal northern California during the past 16,000years", "Sea surface temperatures in the subarctic northeast Pacific reflect millennial-scale climate oscillations during the last 16kyrs", "Morphologic and stratigraphic evidence for Allerd and Younger Dryas age glacier fluctuations of the Cordilleran ice sheet, British Columbia, Canada, and northwest Washington, U.S.A", "Post-glacial climate and fire-mediated vegetation change on the western Olympic Peninsula, Washington, USA", "Evidence for millennial-scale climate change during Marine Isotope Stages2 and 3 at Little Lake, western Oregon, USA", "Carbon isotopes from fossil packrat pellets and elevational movements of Utah agave plants reveal the Younger Dryas cold period in Grand Canyon, Arizona", "Small game, the younger dryas, and the transition to agriculture in the southern levant", 10.1130/0091-7613(1995)023<0004:RDDTLD>2.3.CO;2, "Was the Younger Dryas triggered by a flood? tooltip.className = '_error-inner _no_arrow'; [38], Although the start of the Younger Dryas is regarded to be synchronous across the North Atlantic region, recent research concluded that the start of the Younger Dryas might be time-transgressive even within there. ( CC BY-SA 2.0 ) But if this is true, then the Carolina Bay impacts must be coincident with a mass extinction of fauna, especially in North America, and also coincident with a major change in the climate of the . script.src = url; [5], The Younger Dryas did not affect the climate worldwide. A team of researchers have uncovered evidence that a Mega-Flood, or series of megafloods, from beneath the Ice Age Laurentide Ice Sheet shaped the Bahama Islands. elem.parentNode.appendChild(tooltip); no_error = elem.checked; Effects of the Younger Dryas were of varying intensity throughout North America. Originally the ice-sheets were thought to have melted over tens of thousands of years in a very slow process. 12,000 years great flood in the bible (Gilgamesh and Hobabish betray a Babylonian provenance .

for (var i = 0; i < allInputs.length; i++) { And that means the findings may also represent the trigger for the Younger Dryas. var wrapper = document.createElement('div'); div.className = '_error-html'; World Map with Meteor Impact Craters . It's pretty much based on the information in @Pierre 's "Cometary Encounters" book. The YD is an invaluable case study: it . Giant boulder in Eastern Washington carried by ice during the Missoula Flood. The term 'IO' is my abbreviation for the 'Impacting Object' that . Today, we are blessed with technology that allows swift recording of geological land features. Journal of Quaternary Science, 33(1), 154. According to the changes, the Younger Dryas occurred as early as around 12,900~13,100calibrated years ago along latitude 5654N. The end of the Younger Dryas has been dated to around 11,550years ago, occurring at 10,000BP (uncalibrated radiocarbon year), a "radiocarbon plateau" by a variety of methods, mostly with consistent results: The International Commission on Stratigraphy put the start of the Greenlandian stage, and implicitly the end of the Younger Dryas, at 11,700years before 2000. [17], In addition to the Younger, Older, and Oldest Dryases, a century-long period of colder climate, similar to the Younger Dryas in abruptness, has occurred within both the Blling oscillation and the Allerd oscillation interstadials. During the Younger Dryas period there was an unexplained extinction of 75% of the North American megafauna. addEvent(input, 'change', function() { Glacial landsystems, retreat dynamics and controls on Loch Lomond Stadial (Younger Dryas) glaciation in Britain. and tamarack (Larix laricina) boreal forests that later changed rapidly to temperate, more broad-leaf tree forest conditions at the end of the Younger Dryas period. (2016, 2018a, 2018b). var err = form_to_submit.querySelector('._form_error'), no_error = true; return match ? The advance is similar in age to the Two Creeks forest bed in Wisconsin. Required fields are marked *. The analysis of Greenland Summit ice cores, as part of the Greenland Ice Sheet Project2 and Greenland Icecore Project, estimated that the Younger Dryas started about 12,800ice (calibrated) yearsBP. The glacial geomorphology of the Loch Lomond Stadial in Britain: a map and geographic information system resource of published evidence. These Mega-Floods traveled down the Mississippi River Valley and into the gulf of Mexico. resource if (!value.match(/^\d\d\d\d-\d\d-\d\d$/)) { The preceding Allerd warm period (interstadial) is subdivided into three events: Greenland Interstadial-1c to 1a (GI-1c to GI-1a). One so . TY - JOUR. }; Across North America lie Bretzs noted scars of a huge body of water that flooded prehistoric earth. }); } else if (elem.tagName == 'SELECT') { The cooling not only favored the expansion of cold-tolerant, light-demanding plants and associated steppe fauna, but also led to regional glacial advances in Scandinavia and a lowering of the regional snow line.[7]. head.appendChild(script); What about a glaciated valley? button.parentNode.insertBefore(wrapper, button); 65,000 y.a., during part of an intense cold stage between 75,000 & 58,000 years ago (Oxygen Isotope Stage 4). [Google Scholar . With temperature changes of up to 15 degrees in as little as a few years, scientists began to see that our prehistory was more catastrophic than first thought. Interpretations of data from Chinese also confirm that the Younger Dryas East Asia lags the North Atlantic Younger Dryas cooling by at least 200~300years. [55][56][57][58] Proxy indicators show that summer temperature conditions in Maine decreased by up to 7.5C. But in this video, I want to go back to the beginning of the Younger Dryas, around 12.800 years ago when a cataclysm of some kind plunged the planet back into an ice age and led to a major megafaunal extinction. The size of the geological scar on the land was so large that the geologist community estimated it to burst as much as seven times. [72] Evidence also indicates an increase in precipitation in New Mexico because of the same Gulf conditions that were influencing Texas. var time = now.getTime(); var elems = form_to_submit.elements[elem.name]; Journal of Maps, 12(5), 11781186. You may wish to turn Basemap to Light Grey Canvas if drawing time is slow. Its date is not well defined, with estimates varying by 400 years, but its duration is agreed to have been around 200 years. Temperature-sensitive lipids, long chain alkenones, found in lake and marine sediments, are well-regarded as a powerful paleothermometer for the quantitative reconstruction of past continental climates. The Younger Dryas Glacial Map includes all the geomorphological information relating to the Younger Dryas glaciation of the UK. elem.className = elem.className + ' _has_error'; var fieldVal = getUrlParam(allInputs[i].dataset.name); Here, you can explore the glaciation of the UK during the Younger Dryas glaciation. This event triggered extensive biomass burning, brief impact winter, climate change, and contributed to extinctions of late . More information. Therefore, continuous freshwater input was necessary to maintain a weak AMOC for more than 1,000years. careers The 1300-year-long Younger Dryas cold reversal (12,900-11,600 cal BP) is seen most clearly in Greenland ice cores. e.preventDefault(); You can therefore view the attribute data held for each layer in the current map view. Flood maps show how likely it is for an area to flood. Using the instructions above, allow the students to explore, interact with, and get used to the map. A complementary drop in the 18 O in shells from the St. Lawrence Valley at the onset of the Younger Dryas would provide support for the Lake Agassiz flood scenario. [88] On the Olympic Peninsula, a mid-elevation site recorded a decrease in fire, though forest persisted and erosion increased during the Younger Dryas, suggesting cool and wet conditions. Launch the Younger Dryas Glacial Map by clicking here. The Younger Dryas impact hypothesis (YDIH) or Clovis comet hypothesis is a speculative attempt to explain the onset of the Younger Dryas (YD) as an alternative to the long-standing and widely accepted cause due to a significant reduction or shutdown of the North Atlantic "Conveyor" in response to a sudden influx of freshwater from Lake Agassiz and deglaciation in North America. In the late Younger Dryas, the flood activity increased, which resulted in covering the valley floor with a thick layer of sandy and silty sandy overbank alluvia. tidewater glacier But others have held out, suggesting that volcanic eruptions or, what seems to be the leading favorite, some sort of massive freshwater flood temporarily disrupted climate cycles based out of the North Atlantic. thank_you.style.display = 'block'; Note: Earth-Pages will be closing as of early July, but will continue in another form at Earth-logs A sudden collapse of global climate around 12.8 ka and equally brusque warming 11.5 ka ago is called the Younger Dryas.