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Topic: Younger Dryas

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	Younger Dryas - Wikipedia, the free encyclopedia
		The Younger Dryas saw a rapid return to glacial conditions in the higher latitudes of the Northern Hemisphere between 12,900 – 11,500 years before present (BP)[2] in sharp contrast to the warming of the preceding interstadial deglaciation.
		In western Europe and Greenland, the Younger Dryas is a well-defined synchronous cool period [4].
		The prevailing theory holds that the Younger Dryas was caused by a significant reduction or shutdown of the North Atlantic thermohaline circulation in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America.
	en.wikipedia.org /wiki/Younger_Dryas (1121 words)

	PROXY DATA AND CLIMATE MODELING (Site not responding. Last check: 2007-10-22)
		To simulate a Younger Dryas climate, the boundary conditions (that drive the model) were changed according to the Younger Dryas situation.
		Mean annual temperatures were between -1 and -8°C. Younger Dryas winter temperatures were ~20°C lower than today, the temperatures ranging from -15 to -23°C. During the first and coldest part of the Younger Dryas a temperature gradient of ~5°C existed between 50 and 55°N, i.e., northern France/central Germany and southern Sweden.
		Younger Dryas annual temperature ranges, indicating the difference between mean winter and mean summer temperature, were near 30°C throughout the study area.
	www.geo.vu.nl /users/renh/ngsreneabs.html (629 words)

	Abrupt Climate Change Paleo Perspective Data- Abrupt Climate Change During Glacial Times
		The Younger Dryas was an over 1,000 year long cold period between the last ice age and modern conditions.
		It was not until the 1989-1994 U.S. and European projects GISP2 and GRIP drilled their long ice cores in Greenland that scientists could understand the rapidity with which climate changed during the Younger Dryas (Alley 2000, Cuffey and Clow 1997).
		Records of the Younger Dryas are prominent across most of the northern hemisphere, and some manifestations of the event may spread worldwide.
	www.ncdc.noaa.gov /paleo/abrupt/data_glacial.html (510 words)

	Abrupt Climate Change - the Younger Dryas
		Dryas octopetala is a flower in the Rosaceae family, typical of cold, open, Arctic environments.
		The shift was termed the Younger Dryas, as it was the youngest shift to cold conditions, and the most pronounced all over Europe.
		This is the earliest human occupation of North America and during the Younger Dryas, the Mesa site was abandoned as cold, drier conditions ensued.
	www.ldeo.columbia.edu /res/pi/arch/peteet.shtml (196 words)

	BBC - h2g2 - Younger Dryas - the Ice Age's Last Big Blast - A760240
		The climatic conditions of mid-latitude regions during the Younger Dryas were probably similar to those of Siberia and northern Canada today.
		The worst effects of the Younger Dryas period lasted around 1300 years, but it was over by 11,000 BP (Before Present)5 and the unprecedented warm stage of the current times began.
		It is believed that the Younger Dryas may have happened due to the melting of ice caps in the post-Ice Age warming period.
	www.bbc.co.uk /dna/h2g2/plain/A760240 (1021 words)

	Climate variation in the tropical Pacific: coral provides proof
		The Younger Dryas period, about 12 000 years ago, was marked by a sharp cooling event in the Northern Hemisphere.
		The temperature curves drawn from fossil Diploastrea data show that during the Younger Dryas period the STT around Vanuatu was on average 4.5°C lower than at present (2).
		This situation is similar to that observed in Vanuatu during the Younger Dryas period, but quite different to the present prevailing situation.
	www.eurekalert.org /pub_releases/2004-05/idrp-cvi_1050604.php (955 words)

	IS THE YOUNGER DRYAS GLOBAL IN EXTENT? (Site not responding. Last check: 2007-10-22)
		Evidence for the Younger Dryas cooling event (~10,500 - 13,000 calendar years ago) is found in a variety of climatic proxies, such as variations in pollen records, composition of ice cores, grain size in loess deposits, chemistry of ocean sediments, and the presence of glacial moraines.
		The Younger Dryas is well established in the North Atlantic region becoming more problematic in both evidence and chronological control in other areas of the world.
		Nevertheless, the Younger Dryas appears to be global in scale, albeit the signals vary in strength.
	gsa.confex.com /gsa/2003AM/finalprogram/abstract_63494.htm (359 words)

	Géographie physique et quaternaire : LAKE-LEVEL FLUCTUATIONS AT LE LOCLE, SWISS JURA, FROM THE YOUNGER DRYAS TO ... (Site not responding. Last check: 2007-10-22)
		Tentative reconstruction of the lake-level fluctuations at Le Locle from the late Younger Dryas to the mid-Holocene.
		Outlines of the climate during the Egesen advance (Younger Dryas, 11 000-10 000 BP) in the central Alps of the western Tyrol, Austria.
		Younger Dryas and early Holocene lake-level fluctuations in the Jura mountains, France.
	www.erudit.org /revue/gpq/1999/v53/n2/005693ar.html (9260 words)

	Geokolloquium WS 2004/2005
		Although the climatic impact of the Younger Dryas was largest in the North-Atlantic realm, it affected climate at a global scale.
		Recently, it has been proposed that the Younger Dryas was a unique event and should be regarded as an "accident" during the last deglaciation.
		Here, the Younger Dryas is considered in the framework of climate change at millennial timescales during the late Pleistocene (i.e., Dansgaard-Oeschger events).
	www.uni-heidelberg.de /institute/fak12/geol/Promotion/Geokoll_abstracts/schulz.html (280 words)

	Global Climate Change Student Guide
		This event is known as the Younger Dryas Cooling.
		The Younger Dryas cooling event may have been caused by meltwater-induced changes in the atmosphere-ocean circulation.
		Unfortunately, evidence of CO reduction during the Younger Dryas (Stauffer et al., 1985) remains inconclusive.
	www.ace.mmu.ac.uk /Resources/gcc/5-3-2-1.html (304 words)

	Younger Dryas Paleoclimate Data; GISS, NY
		In the northeastern U.S., the Younger Dryas event is regionally apparent from pollen records that indicate a change from a mixed hardwood deciduous forest (oak, ash, spruce, fir) to a boreal assemblage (spruce, fir, larch, birch, alder) as seen in pollen zones A-3 and A-4 in the first figure.
		The close of the Younger Dryas cooling, typified by a vegetation change from boreal trees to a warmer white pine and oak forest, took place over an interval of between 50 and 150 years.
		However, we are continuing to assess reports of the Younger Dryas in locations further afield, specifically with a research program of glacial geology and palynology at high latitudes, including Kodiak Island, Alaska.
	gcmd.gsfc.nasa.gov /records/GCMD_EARTH_LAND_GISS_Paleocl_Dryas1.html (1197 words)

	the Slovenian (Site not responding. Last check: 2007-10-22)
		The Younger Dryas cold period was first noticed in the pollen records of NW Europe, but it has since been found to have been a major climate event across Europe, Eurasia, eastern North America, and possibly many other areas around the world (Starkel 1991, Jalut 1992, Velichko 1993).
		The 1,300-year Younger Dryas interval seems to be marked by a hiatus in human occupation of northern Europe, and its ending closely corresponds to the beginning of the Mesolithic in Europe (ref.s).
		A priori, the rapid onset of severe aridity and lower temperatures of the Younger Dryas event would be expected to result in a major reduction in population densities across most of Europe and the near east.
	home.cogeco.ca /~slovenianamerica/articles/adams1.htm (1994 words)

	Nat' Academies Press, Abrupt Climate Change: Inevitable Surprises (2002)
		In the Santa Barbara Basin (Kennett and Ingram, 1995) and the Gulf of California (Keigwin and Jones, 1990), sediments that are normally anoxic became oxic during the Younger Dryas.
		Between 20°N and 20°S, Younger Dryas cooling is observed on the basis of alkenone paleothermometry (Bard et al., 1997).
		Broadly, however, the Younger Dryas was a cold, dry, and windy time in much of the world although with locally wetter regions probably linked to storm-track shifts.
	www.nap.edu /books/0309074347/html/35.html (676 words)

	Sailer, Kerschner and Heller
		Three-dimensional reconstruction of Younger Dryas glaciers with a raster-based GIS
		In the case of the Younger Dryas climatic fluctuation, this has been done recently by Renssen (1997).
		The ELA depression for the Kartell stadial in the upper part of Ochsental is -90 m, which is the same as at the type locality (Fraedrich 1979).
	ggg.qub.ac.uk /papers/full/1999/rp011999/rp01.html (4278 words)

	Abrupt Climate Change Paleo Perspective Story- Mechanisms- Thermohaline & Vegetation
		Scientists have found evidence in paleoclimate records that the Younger Dryas was caused by a change in the ocean thermohaline circulation.
		The Younger Dryas occurred during the transition from the last glacial period into the present interglacial (the Holocene).
		The Younger Dryas in the GISP2 ice core (Cuffey and Clow (1997) and Alley (2000)) and reconstructed freshwater flux into the North Atlantic (Clark et al., 2001).
	www.ncdc.noaa.gov /paleo/abrupt/story3.html (619 words)

	Did Indo-European Languages spread before farming? (Site not responding. Last check: 2007-10-22)
		In Europe and most of the Near East the record of human occupation during the Younger Dryas is ambiguous, with the 'age plateau' in radiocarbon ages adding to the confusion (10,000 years ago in radiocarbon terms can mean anything between 11,200 to 12,200 'real' years ago).
		The post-Younger Dryas colonization hypothesis is only one of a range of potential scenarios, suggested by the paleoenvironmental and archaeological record, leading to the spread of Indo-European languages, or higher-order language groups such as the paired Indo-European/Uralic familes, or the still broader and more heterogenous Nostratic superfamily.
		A major refuge of population in the Europe-west Asian region during the Younger Dryas seems to have been the general area around the Jordan Valley, where populations clustered in moist sites where wild nuts and grains could be gathered.
	hindunet.org /saraswati/aryan/Indo2.html (3739 words)

	Andrew Marc Solod Festival of Science 2001 Poster Presentation
		Recognition of the Younger Dryas Cold Episode at Glovers Pond Northwestern N.J. The last de-glaciation period between 20,000-8,000 B.P. was punctuated by rapid global and regional climate fluctuations.
		Erickson and Carpenter, (1998) have demonstrated the presence of the Younger Dryas at Glovers Pond through isotope analysis.
		The Preboreal, Younger Dryas, and Older Dryas?, are defined by higher population count, increased genera diversity, and increased taphonomic preservation, compared against the Allerod episode.
	it.stlawu.edu /~math/activities/FOS/FOS2001/FOS2001PosterPres/FOS2001ASolod.htm (404 words)

	W. S. Broecker, "What If the Conveyor Were to Shut Down?" GSA Today 9(1):1-7 (January 1999)
		Nevertheless, it is worthwhile to compare the climate of the late Allerød with that of the Younger Dryas.
		The trigger for the precipitous Younger Dryas cooling as first proposed by Rooth (1982) was likely the large pulse of fresh water released into the northern Atlantic as a result of the sudden switch in the outlet of proglacial Lake Agassiz from the Mississippi to the St. Lawrence drainage.
		During the course of the 50 000-yr-duration glacial period, 20 climate shifts similar to that marking the beginning of the Younger Dryas occurred.
	faculty.washington.edu /wcalvin/teaching/Broecker99.html (4292 words)

	Huelmo/Mascardi Cold Reversal - Wikipedia, the free encyclopedia
		This cooling began about 550 years before the Younger Dryas cooling in the Northern Hemisphere, and both periods ended at about the same time.
		C yr BP ((13,400 calendar years BP) event onset took place 400-700 years before the onset of the Younger Dryas event.
		C yr BP (circa 11,500 cal yr BP) end date is difficult to calibrate to a calendar year because it took place during a radiocarbon age plateau.
	en.wikipedia.org /wiki/Huelmo/Mascardi_Cold_Reversal (210 words)

	Articles - Younger Dryas (Site not responding. Last check: 2007-10-22)
		The Younger Dryas stadial, named after the alpine / tundra wildflower ´´Dryas octopetala´´, and also referred to as the ´´Big Freeze´´ [1], was a brief (approximately 1300 Â± 70 years.
		An ´´Older Dryas´´ stadial had preceded the AllerÃ¸d, approximately 1000 years before the Younger Dryas; it lasted 300 years.
		In western Europe and Greenland, the Younger Dryas is a well-defined synchronous cool period.
	www.sewing-center.com /articles/Younger_Dryas (1016 words)

	Climate Change 2001: The Scientific Basis
		The deglaciation was accomplished in two main stages, with a return to colder conditions (Younger Dryas/Antarctic Cold Reversal) or, at the least, a pause in the deglaciation.
		The return to the cold conditions of the Younger Dryas from the incipient inter-glacial warming 13,000 years ago took place within a few decades or less (Alley et al., 1993).
		The warming phase, that took place about 11,500 years ago, at the end of the Younger Dryas was also very abrupt and central Greenland temperatures increased by 7°C or more in a few decades (Johnsen et al., 1992; Grootes et al., 1993; Severinghaus et al., 1998).
	www.grida.no /climate/ipcc_tar/wg1/074.htm (1549 words)

	Atlas: Younger Dryas Equilibrium Line Altitudes and Rockglaciers in the Ferwall-Group (Western Tyrol, Austria) by ...
		The reconstruction of the ELA (equilibrium line altitude) is based on numerous well documented end- and lateral moraines of the Younger Dryas "Egesen Stadial", which was distinctly three-phased.
		In some cirques, areas which were glacierized during the Egesen maximum (early Younger Dryas) have been covered subsequently by large rockglaciers down to 1900 m after deglaciation.
		Preliminary results show that precipitation during the maximum Egesen advance (early Younger Dryas) was about 80 -100 % of modern precipitation rates in the Ferwall Group, which is typical for areas closer to the western fringe of the Austrian Alps (Kerschner et al.
	atlas-conferences.com /c/a/h/i/92.htm (579 words)

	Reconstructing the phytoplankton community of the Cariaco Basin during the Younger Dryas cold event using chlorin ...
		A record of the downcore distribution of chlorin steryl esters (CSEs) through the Younger Dryas was produced from Cariaco Basin sediments in order to assess the potential use of CSEs as recorders of the structure of phytoplankton communities through time.
		During the Younger Dryas, enhanced upwelling in the Cariaco Basin caused an increase in the diatom population and therefore an increase in the relative abundance of CSEs derived from diatoms.
		In contrast, the dinoflagellate population, and therefore CSEs derived from dinoflagellates, decreased in response to the climate change during the Younger Dryas.
	www.agu.org /pubs/crossref/2004/2003PA000907.shtml (335 words)

	Science Bulletins \| Earth \| Feature \| Melting Glaciers: Clues to Climate Change \| The Climate Jump Heard 'Round The ...
		They’ve discovered over the last 15 years that the Younger Dryas was felt not just in the North Atlantic, but over half the globe.
		The abrupt climate changes of the Younger Dryas likely stimulated dust storms similar to this April 2005 storm in western China's Taklimakan Desert, as viewed by satellite.
		The positions of the moraines, which depend on the positions of the glaciers from which they were deposited, indicated to the group that Greenland temperatures during the Younger Dryas were only 4 to 6 degrees C colder than they are now.
	sciencebulletins.amnh.org /earth/f/glaciers.20050331/essays/59_1.php (892 words)

	News: "The Day After Tomorrow"- could the Younger Dryas happen again?
		However, while this scenario is unlikely, scientists continue to make observations that are relevant to this question and refine the models that are used for climate change scenarios.
		NSIDC: Past events, like the Younger Dryas, show that climate can respond in rapid and hard-to-predict ways to slow persistent forcings (a push on the climate system, such as excess heat in the atmosphere or ocean, wind shifts, or density changes in ocean water).
		One of the major differences between the present-day situation and the past is that the current forcing, greenhouse gases in the atmosphere, is unlike forcings that led to past climate changes (such as changes in Earth’s orbit, or solar influences).
	nsidc.org /news/press/day_after/q8.html (229 words)

	Research Opportunity 12
		The Younger Dryas (YD) is the prototypical abrupt climate event - atmospheric temperatures in the North Atlantic region dropped by as much as 10°C in as little as a few decades ~ 12.8 ky BP– during the rapid warming following the last glacial maximum ~ 24 ky BP.
		The most widely accepted hypothesis to explain the Younger Dryas cooling event is massive freshwater discharge of glacial-lake and ice-sheet melt water from North America out the St. Lawrence River Estuary, which may have diluted North Atlantic surface water salinity and slowed down the global ocean thermohaline circulation.
		This is because the region’s stratigraphic record of paleo-lake sedimentation prior to and at the onset of the Younger Dryas provides an opportunity to reconstruct at a high temporal resolution the sequence of events during the northward retreat of the Laurentide Ice Sheet margin in this critical area.
	geology.usgs.gov /postdoc/2006/opps/opp12.html (851 words)

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