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The
Younger Dryas stadial, named after the alpine / tundra wildflower
Dryas octopetala, and also referred to as the
Big Freeze,Berger, W.H.: "The Younger Dryas cold spell – a quest for causes.", page 219-237.
Palaeogeography, Palaeoclimatology, Palaeoecology (Global and Planetary Change Section) 89, 1990 was a brief (approximately 1300 ± 70 years ) cold climate period following the Bölling/
Allerød Oscillation interstadial at the end of the Pleistocene between approximately 12,700 to 11,500 years Before Present, How Rapidly did Climate Change in the Distant Past?, Climate Change 2001: Working Group I: The Scientific Basis, Intergovernmental Panel on Climate Change and preceding the
Boreal (period) of the early Holocene. In Ireland, the period has been known as the
Nahanagan Stadial, while in the UK it has been called the
Loch Lomond Stadial and most recently Greenland Stadial 1 (GS1). See INTIMATE Project (Integration of Ice, Marine and Terrestrial records), an INQUA Palaeoclimate subcommittee.
The Younger Dryas (GS1) is also a
Blytt-Sernander climate period detected from layers in north European bog peat. It is dated approximately 12,900-11,500 Before Present calibrated, or 11,000-10,000 BP uncalibrated. An
Older Dryas stadial had preceded the Allerød, approximately 1000 years before the Younger Dryas; it lasted 300 years.
Abrupt climate change
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)Alley, R.B.: "The Younger Dryas cold interval as viewed from central Greenland.", page 213-226.
Quaternary Science Reviews 19, 2000 in sharp contrast to the warming of the preceding interstadial glaciation. The transitions each occurred over a period of a decade or so Alley
et al.: "Abrupt accumulation increase at the Younger Dryas termination in the GISP2 ice core", page 527-529.
Nature 362, 1993.Thermally fractionated nitrogen and argon isotope data from
Greenland ice core GISP2 indicates that the summit of Greenland was ~15 °C colder during the Younger Dryas than today. In the UK, beetle (fossil beetle) evidence suggests mean annual temperature dropped to approximately 5 °C Severinghaus, J.P.: "Timing of abrupt climate change at the end of the Younger Dryas interval from thermally fractionated gases in polar ice.", page 141-146.
Nature 391, 1998, and periglacial conditions prevailed in lowland areas, while icefields and
glaciers formed in upland areas Atkinson, T.C.: "Seasonal temperatures in Britain during the past 22,000 years, reconstructed using beetle remains.", page 587-592.
Nature 325, 1987. Nothing of the size, extent, or rapidity of this period of
abrupt climate change has been experienced since .
Was the Younger Dryas global?
Answering this question is hampered by the lack of a precise definition of "Younger Dryas" in all the records. In western Europe and Greenland, the Younger Dryas is a well-defined synchronous cool period. But cooling in the tropical North Atlantic may have preceded this by a few hundred years; South America shows a less well defined initiation but a sharp termination. The Antarctic Cold Reversal appears to have started a thousand years before the Younger Dryas, and has no clearly defined
:Image:Epica-vostok-grip-40kyr-HCO.png; Huybers has argued that there is fair confidence in the absence of the Younger Dryas in Antarctica, New Zealand and parts of Oceania. Similarly the Southern Hemisphere cooling known as the Deglaciation Climate Reversal (DCR) began approximately 1kyr before the YD, between 14kya and 11.5 kya as noted in the Sajama ice core. The Andean climate returned to LGM conditions with colder temperatures coupled with higher precipitation (high lake stands in the
Altiplano). Thompson
et al., 2000.
In western North America it is likely that the effects of the Younger Dryas were less intense than in Europe however evidence of glacial re-advance Friele, P.A., Clague, J.J.: "Younger Dryas readvance in Squamish river valley, southern Coast mountains, British Columbia.", page 1925-1933.
Quaternary Science Reviews 21, 2002 indicates Younger Dryas cooling in the pacific Northwest.
Other features seen include:
- Replacement of forest in Scandinavia with glacial tundra (which is the habitat of the plant Dryas (plant)).
- Glaciation or increased snow in mountain ranges around the world.
- Formation of solifluction layers and loess deposits in Northern Europe.
- More dust in the Earth's atmosphere, originating from deserts in Asia.
- Drought in the Levant, perhaps motivating the Natufian culture to invent agriculture.
- The Huelmo/Mascardi Cold Reversal in the Southern Hemisphere began slightly before the Younger Dryas and ended at the same time.
Causes of the Younger Dryas
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. The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the north Atlantic Ocean. This theory does not explain why
South America cooled first.
Previous glacial terminations probably did not have Younger Dryas-like events, suggesting that whatever the mechanism is, it has a random component.
However there is evidence that termination II had a post glacial cooling period similar to the younger Dryas but lasting longer and being more severe.
There is evidence that the so-called
Younger Dryas impact event, 12,900 years ago in North America could have initiated the Younger Dryas cooling.
The end of the Younger Dryas
Measurements of oxygen isotopes from the GISP2 ice core suggest the ending of the Younger Dryas took place over just 40 - 50 years in three discrete steps, each lasting five years. Other proxy data, such as dust concentration, and snow accumulation, suggest an even more rapid transition, requiring a ~7 °C warming in just a few years. Sissons, J.B.: "The Loch Lomond stadial in the British Isles.", page 199-203.
Nature 280, 1979 Alley, R.B.,
et al.: "Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event.", page 527-529.
Nature 362, 1993 Dansgaard, W.,
et al.: "The abrupt termination of the Younger Dryas climate event.", page 532-534.
Nature 339, 1989
The end of the Younger Dryas has been dated to around 9600 BC (11550 calendar years BP, occurring at 10000
radiocarbon years BP, a "radiocarbon plateau") by a variety of methods, with mostly consistent results:
11530±50 BP -- GRIP ice core, Greenland Taylor, K.C.,
et al.: "The Holocene-Younger Dryas transition recorded at Summit, Greenland.", page 825-827.
Science 278, 1997
11530+40-60 BP --
Kråkenes Lake, western
Norway. Spurk, M.,
et al.: "Revisions and extension of the Hohenheim oak and pine chronologies: New evidence about the timing of the Younger Dryas/Preboreal transition", page 1107-1116.
Radiocarbon 40, 1998
11570 BP --
Cariaco Basin core, Venezuela Gulliksen, S.,
et al.: "A calendar age estimate of the Younger Dryas-Holocene boundary at Krakenes, western Norway", page 3, 249-259.
Holocene 8, 1998
11570 BP -- German
oak/pine dendrochronology "Hugheus radiocarbon and climate shifts during the last deglaciation", page 5498, 1951-1954.
Science 290
11640±280 BP -- GISP2 ice core, Greenland
The Younger Dryas and the beginning of agriculture
The Younger Dryas is often linked to the adoption of agriculture in the
Levant.Bar-Yosef, O. and A. Belfer-Cohen: "Facing environmental crisis. Societal and cultural changes at the transition from the Younger Dryas to the Holocene in the Levant." In:
The Dawn of Farming in the Near East. Edited by R.T.J. Cappers and S. Bottema, pp. 55-66. Studies in Early Near Eastern Production, Subsistence and Environment 6. Berlin: Ex oriente. It is argued that the cold and dry Younger Dryas lowered the carrying capacity of the area and forced the sedentary Early
Natufian population into a more mobile subsistence pattern. Further climatic deterioration is thought to have brought about cereal cultivation. While there exists relative consensus regarding the role of the Younger Dryas in the changing subsistence patterns during the Natufian, its connection to the beginning of agriculture at the end of the period is still being debated.Munro, N. D.: "Small game, the younger dryas, and the transition to agriculture in the southern levant", page 47–64.
Mitteilungen der Gesellschaft für Urgeschichte 12, 2003 See the Neolithic Revolution, when hunter gatherers turned to farming.
See also
- 1500-year climate cycle
- Timeline of glaciation
- Timeline of environmental events
- Older Dryas
- Little Ice Age
- Medieval Warm Period
Notes
External links
- Study Confirms Mechanism for Current Shutdowns, European Cooling, Oregon State University press release (10 April 2007)
- Younger Dryas Caused by ET Impact
- W. S. Broecker, "What If the Conveyor Were to Shut Down? Reflections on a Possible Outcome of the Great Global Experiment"
- Paul A. Mayewski and Michael Bender, "The GISP2 ice core record: The Younger Dryas"
- ARIC Global Climate Change Student Guide 5.3.2.1. The Younger Dryas Event
- William C. Calvin, "The great climate flip-flop" adapted from Atlantic Monthly, 281(1):47-64 (January 1998).
- Lamont-Doherty Earth Observatory, "Two examples of abrupt climate change: 1. The Younger Dryas"
- Lev Tarasov and W.R. Peltier, "Arctic freshwater forcing of the Younger Dryas cold reversal" letter, in Nature 435, 662-665 (2 June 2005)
- "Hugheus radiocarbon and climate shifts during the last deglaciation"
- Friedrich, M., et al. (1999), Paleo-environment and radiocarbon calibration as derived from Lateglacial/Early Holocene tree-ring chronologies
- Munro, N. D. "Small game, the younger dryas, and the transition to agriculture in the southern levant"
- Younger Dryas (YD) Impact AGU Press Conference - YouTube Playlist
The
Younger Dryas stadial, named after the alpine / tundra wildflower
Dryas octopetala, and also referred to as the
Big Freeze,Berger, W.H.: "The Younger Dryas cold spell – a quest for causes.", page 219-237.
Palaeogeography, Palaeoclimatology, Palaeoecology (Global and Planetary Change Section) 89, 1990 was a brief (approximately 1300 ± 70 years ) cold
climate period following the Bölling/Allerød Oscillation interstadial at the end of the Pleistocene between approximately 12,700 to 11,500 years Before Present, How Rapidly did Climate Change in the Distant Past?, Climate Change 2001: Working Group I: The Scientific Basis, Intergovernmental Panel on Climate Change and preceding the Boreal (period) of the early Holocene. In Ireland, the period has been known as the
Nahanagan Stadial, while in the UK it has been called the
Loch Lomond Stadial and most recently Greenland Stadial 1 (GS1). See INTIMATE Project (Integration of Ice, Marine and Terrestrial records), an INQUA Palaeoclimate subcommittee.
The Younger Dryas (GS1) is also a
Blytt-Sernander climate period detected from layers in north European bog peat. It is dated approximately 12,900-11,500 Before Present calibrated, or 11,000-10,000 BP uncalibrated. An
Older Dryas stadial had preceded the Allerød, approximately 1000 years before the Younger Dryas; it lasted 300 years.
Abrupt climate change
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)Alley, R.B.: "The Younger Dryas cold interval as viewed from central Greenland.", page 213-226.
Quaternary Science Reviews 19, 2000 in sharp contrast to the warming of the preceding interstadial glaciation. The transitions each occurred over a period of a decade or so Alley
et al.: "Abrupt accumulation increase at the Younger Dryas termination in the GISP2 ice core", page 527-529.
Nature 362, 1993.Thermally fractionated nitrogen and argon isotope data from
Greenland ice core GISP2 indicates that the summit of Greenland was ~15 °C colder during the Younger Dryas than today. In the UK, beetle (fossil beetle) evidence suggests mean annual temperature dropped to approximately 5 °C Severinghaus, J.P.: "Timing of abrupt climate change at the end of the Younger Dryas interval from thermally fractionated gases in polar ice.", page 141-146.
Nature 391, 1998, and periglacial conditions prevailed in lowland areas, while icefields and
glaciers formed in upland areas Atkinson, T.C.: "Seasonal temperatures in Britain during the past 22,000 years, reconstructed using beetle remains.", page 587-592.
Nature 325, 1987. Nothing of the size, extent, or rapidity of this period of abrupt climate change has been experienced since .
Was the Younger Dryas global?
Answering this question is hampered by the lack of a precise definition of "Younger Dryas" in all the records. In western Europe and Greenland, the Younger Dryas is a well-defined synchronous cool period. But cooling in the tropical North Atlantic may have preceded this by a few hundred years; South America shows a less well defined initiation but a sharp termination. The Antarctic Cold Reversal appears to have started a thousand years before the Younger Dryas, and has no clearly defined :Image:Epica-vostok-grip-40kyr-HCO.png; Huybers has argued that there is fair confidence in the absence of the Younger Dryas in Antarctica, New Zealand and parts of Oceania. Similarly the Southern Hemisphere cooling known as the Deglaciation Climate Reversal (DCR) began approximately 1kyr before the YD, between 14kya and 11.5 kya as noted in the Sajama ice core. The Andean climate returned to LGM conditions with colder temperatures coupled with higher precipitation (high lake stands in the Altiplano). Thompson
et al., 2000.
In western North America it is likely that the effects of the Younger Dryas were less intense than in Europe however evidence of glacial re-advance Friele, P.A., Clague, J.J.: "Younger Dryas readvance in Squamish river valley, southern Coast mountains, British Columbia.", page 1925-1933.
Quaternary Science Reviews 21, 2002 indicates Younger Dryas cooling in the pacific Northwest.
Other features seen include:
- Replacement of forest in Scandinavia with glacial tundra (which is the habitat of the plant Dryas (plant)).
- Glaciation or increased snow in mountain ranges around the world.
- Formation of solifluction layers and loess deposits in Northern Europe.
- More dust in the Earth's atmosphere, originating from deserts in Asia.
- Drought in the Levant, perhaps motivating the Natufian culture to invent agriculture.
- The Huelmo/Mascardi Cold Reversal in the Southern Hemisphere began slightly before the Younger Dryas and ended at the same time.
Causes of the Younger Dryas
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. The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the north Atlantic Ocean. This theory does not explain why South America cooled first.
Previous glacial terminations probably did not have Younger Dryas-like events, suggesting that whatever the mechanism is, it has a random component.
However there is evidence that termination II had a post glacial cooling period similar to the younger Dryas but lasting longer and being more severe.
There is evidence that the so-called Younger Dryas impact event, 12,900 years ago in North America could have initiated the Younger Dryas cooling.
The end of the Younger Dryas
Measurements of oxygen isotopes from the GISP2
ice core suggest the ending of the Younger Dryas took place over just 40 - 50 years in three discrete steps, each lasting five years. Other proxy data, such as dust concentration, and snow accumulation, suggest an even more rapid transition, requiring a ~7 °C warming in just a few years. Sissons, J.B.: "The Loch Lomond stadial in the British Isles.", page 199-203.
Nature 280, 1979 Alley, R.B.,
et al.: "Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event.", page 527-529.
Nature 362, 1993 Dansgaard, W.,
et al.: "The abrupt termination of the Younger Dryas climate event.", page 532-534.
Nature 339, 1989
The end of the Younger Dryas has been dated to around 9600 BC (11550 calendar years BP, occurring at 10000 radiocarbon years BP, a "radiocarbon plateau") by a variety of methods, with mostly consistent results:
11530±50 BP -- GRIP
ice core, Greenland Taylor, K.C.,
et al.: "The Holocene-Younger Dryas transition recorded at Summit, Greenland.", page 825-827.
Science 278, 1997
11530+40-60 BP --
Kråkenes Lake, western Norway. Spurk, M.,
et al.: "Revisions and extension of the Hohenheim oak and pine chronologies: New evidence about the timing of the Younger Dryas/Preboreal transition", page 1107-1116.
Radiocarbon 40, 1998
11570 BP -- Cariaco Basin core,
Venezuela Gulliksen, S.,
et al.: "A calendar age estimate of the Younger Dryas-Holocene boundary at Krakenes, western Norway", page 3, 249-259.
Holocene 8, 1998
11570 BP -- German
oak/
pine dendrochronology "Hugheus radiocarbon and climate shifts during the last deglaciation", page 5498, 1951-1954.
Science 290
11640±280 BP -- GISP2 ice core, Greenland
The Younger Dryas and the beginning of agriculture
The Younger Dryas is often linked to the adoption of agriculture in the Levant.Bar-Yosef, O. and A. Belfer-Cohen: "Facing environmental crisis. Societal and cultural changes at the transition from the Younger Dryas to the Holocene in the Levant." In:
The Dawn of Farming in the Near East. Edited by R.T.J. Cappers and S. Bottema, pp. 55-66. Studies in Early Near Eastern Production, Subsistence and Environment 6. Berlin: Ex oriente. It is argued that the cold and dry Younger Dryas lowered the carrying capacity of the area and forced the sedentary Early
Natufian population into a more mobile subsistence pattern. Further climatic deterioration is thought to have brought about
cereal cultivation. While there exists relative consensus regarding the role of the Younger Dryas in the changing subsistence patterns during the Natufian, its connection to the beginning of agriculture at the end of the period is still being debated.Munro, N. D.: "Small game, the younger dryas, and the transition to agriculture in the southern levant", page 47–64.
Mitteilungen der Gesellschaft für Urgeschichte 12, 2003 See the Neolithic Revolution, when hunter gatherers turned to farming.
See also
Notes
External links
- Study Confirms Mechanism for Current Shutdowns, European Cooling, Oregon State University press release (10 April 2007)
- Younger Dryas Caused by ET Impact
- W. S. Broecker, "What If the Conveyor Were to Shut Down? Reflections on a Possible Outcome of the Great Global Experiment"
- Paul A. Mayewski and Michael Bender, "The GISP2 ice core record: The Younger Dryas"
- ARIC Global Climate Change Student Guide 5.3.2.1. The Younger Dryas Event
- William C. Calvin, "The great climate flip-flop" adapted from Atlantic Monthly, 281(1):47-64 (January 1998).
- Lamont-Doherty Earth Observatory, "Two examples of abrupt climate change: 1. The Younger Dryas"
- Lev Tarasov and W.R. Peltier, "Arctic freshwater forcing of the Younger Dryas cold reversal" letter, in Nature 435, 662-665 (2 June 2005)
- "Hugheus radiocarbon and climate shifts during the last deglaciation"
- Friedrich, M., et al. (1999), Paleo-environment and radiocarbon calibration as derived from Lateglacial/Early Holocene tree-ring chronologies
- Munro, N. D. "Small game, the younger dryas, and the transition to agriculture in the southern levant"
- Younger Dryas (YD) Impact AGU Press Conference - YouTube Playlist
BBC - h2g2 - Younger Dryas - the Ice Age's Last Big Blast
h2g2 is the unconventional guide to life, the universe and everything, a guide that's written by visitors to the website, creating an organic and evolving encyclopedia of life
Younger Dryas - Wikipedia, the free encyclopedia
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 ± 70 years ...
Global Climate Change Student Guide
The Younger Dryas Event. Although deglaciation had been taking place for at least 4,000 years, a rapid deterioration (cooling) in climate occurred at about 10 to 11Ka, roughly ...
The Younger Dryas
The Younger Dryas. The Younger Dryas (YD) was the most significant rapid climate change event that occurred during the last deglaciation of the North Atlantic region.
The Younger Dryas
The Younger Dryas The Younger Dryas, is the name given to a cold interval at the end of the last ICE AGE, 11 to 10 thousand years ago. The location of the Younger Dryas, was in ...
The Younger Dryas
The Younger Dryas 24/11/00 Click here to start
UC's Lowell talks about latest in Younger Dryas work in Science ...
UC professor of geology Tom Lowell has authored an article in the July 18 edition of Science, discussing the latest research into determining the impact of the Younger Dryas event ...
Two examples of abrupt climate change
An event that occurred about 12,800 years before present (BP), termed the Younger Dryas (YD), is the canonical example of abrupt climate change.
Younger Dryas (prehistoric climate period) - What does YD stand for ...
Acronym Definition; YD: Yard: YD: Young Democrats: YD: Younger Dryas (prehistoric climate period) YD: Year-to-Date: YD: Year Date (date on a stamp; philately) YD: Yankee Division ...
BBC - h2g2 - Younger Dryas - the Ice Age's Last Big Blast - A760240
Nothing on Earth has quite the same effect on life and landscape as an Ice Age. It is as if millennia of growth and change are erased and wiped from the record of the Earth, never ...
