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Younger Dryas and the Gulf Stream Urban Myth

  1. Aug 30, 2015 #1
    Every paleo climatology book that discusses the Younger Dryas abrupt cooling event - the Younger Dryas is the name for a period 11,900 years ago when the planet when from interglacial warm to glacial cold with 70% of the cooling occurring in less than a decade and the cold period (during the Younger Dryas 1200 year cold period, the North Atlantic ocean froze each winter to a latitude of Northern Spain and the ice sheets returned to North America, UK, and Northern Europe) lasting for 1200 years, asserts the cause of that abrupt cooling event is somehow related to a melt pulse which interrupts the 'thermalhaline' conveyor and stops the 'Gulf Stream'. How many times have you heard that statement?

    There are three urban legends connected with the Younger Dryas, the Gulf Stream, and cyclic abrupt climate change.

    1) The majority of heat transfer, the reason why Europe in the winter at latitudes above 60N is warmer than the east coast of the US is due to atmospheric transfer of heat, not due to ocean current transfer of heat. A complete stoppage of the North Atlantic drift current (aka the 'Gulf Stream' which is also an urban legend) would only result in cooling of a few degrees in winter in Europe. Stoppage of the Gulf Stream/North Atlantic Drift current could not and did not cause the Younger Dryas abrupt cooling event. Stoppage of the Gulf stream could not and did not cause the 8200 years before present abrupt cooling event.

    http://www.atmos.washington.edu/~david/Gulf.pdf

    This is a 2006 summary of the above paper results which was prepared for a general scientific audience and was published in American Scientist. Highly recommended reading.

    http://www.americanscientist.org/issues/id.999,y.0,no.,content.true,page.1,css.print/issue.aspx

    http://all-geo.org/highlyallochthon...even-scientists-are-afflicted-by-urban-myths/

    Stoppage of the North Atlantic drift current is not 'part of the solution' of cyclic abrupt climate change. The abrupt cooling events in the paleo record are cyclic and have no explanation. The cyclic abrupt cooling events require a massive forcing function to cause the cyclic abrupt cooling.

    2) There is no 'thermalhaline conveyor' in the Atlantic to interrupt. Wally Broeker hypothesized the existence of a discrete thermalhaline conveyor with no proof (Wally's paper includes a picture of the hypothesized discrete conveyor which is repeated ad infinitum.) A melt pulse will not stop the North Atlantic drift current as there is no discrete 'thermalhaline current' to interrupt. Data to support this comment will be included in the next comment.

    3) Tipping points. It is a fact that there is cyclic abrupt climate change in the paleo record. The Younger Dryas is an example of cyclic abrupt climate change. As the massive forcing mechanism that causes cyclic abrupt climate change is not known Wally Broeker also started the urban legend of 'tipping points'.

    The magical tipping point mechanism can only when required amplify a tiny forcing change to cause abrupt change to the earth's climate. If there was massive positive amplification of forcing changes the planet could return to the glacial phase each time there has a major volcanic eruption. If there was positive feedback the planet's temperature would wildly oscillate when there has a major eruption. That is not observed. (More peer reviewed papers and analysis to support the assertion that there is no magical tipping point amplification in later comments.)

    Note this is a 2002 published paper. Thirteen years later the Gulf Stream myth continues.

    As noted in the 2002 paper, the results of the 2002 paper are not surprising (the results are support by an observed temperature difference of the US west coast winter to US east coast in winter which is due to atmospheric transfer of heat from the ocean rather than ocean currents). The 2002 publish paper notes the results are also supported by results in papers published 40 and 50 years previously.

    http://www.atmos.washington.edu/~david/Gulf.pdf

     
    Last edited: Aug 30, 2015
  2. jcsd
  3. Aug 30, 2015 #2
    This is the second part of the urban legend. Wally Broeker drew a picture of a thermalhaline conveyor and included it in a paper. That started the urban legend that there is a discrete thermalhaline conveyor that could be interrupted. Wally later noted his picture was to illustrate a possible hypothesis and said there was no proof that hypothesis was correct. There was no data supplied in Wally's paper to support the assertion of a discrete thermalhaline conveyor.


    Ocean probe data indicates there is no discrete thermalhaline conveyor in the Atlantic ocean. The North Atlantic cold dense high latitude water falls and is then distributed locally in the deep ocean. Only 8% follows the path of the hypothesized conveyor route. There is no discrete thermalhaline conveyor in the North Atlantic to be interrupted.


    http://www.sciencedaily.com/releases/2009/05/090513130942.htm

     
    Last edited: Aug 30, 2015
  4. Aug 31, 2015 #3

    ohwilleke

    User Avatar
    Gold Member

    An abrupt climate change pretty much necessarily implies some sort of tipping point phenomena, even if the exact mechanism isn't known.

    Also, the planet's temperature did wildly oscillate for pretty much the entire time period from the spat of exceptionally frequent and powerful volcano eruptions in Europe near the start of the Upper Paleolithic era that are associated with the decline in Neanderthals and the arrival of modern humans in Europe, to the start of the Holocene, ca. 10kya as show by chart below from a PNAS paper (the dark bars at the bottom right are generated by a primitive farming model and are not historical data). The Neolithic revolution was made possible at that point in large part because the climate finally stopped its wild oscillations.

    F2_medium.gif

    From http://www.pnas.org/content/110/22/8830.full

    While points 1 and 2 may very well be true, the case on point 3 is much weaker.
     
  5. Aug 31, 2015 #4
    Hello,
    What do you think 'jump' or 'tip' means physically in respect to the planet's climate?

    The climate does not 'tip' or 'jump' from one 'state' to another without a physical cause, a physical reason for the observed change. Euphemisms and analogues are used when there is no scientific basis for a claim. There is no magical, 'smart' amplification mechanism that can when required amplify tiny forcing changes to create what is observed. There are no peer reviewed papers that support the assertion of a massive 'smart' amplification mechanism. The 'tip' or 'jump' zombie theory stops people from looking for the physical reason for what is observed. Makes it impossible to solve the problem.

    It is a fact that the paleo data shows evidence of cyclic rapid immense climate changes (as the observed changes are cyclic, periodic, a cyclic forcing function is required to explain periodic, cyclic changes to the planet's climate, as opposed to the alternative which is the massive positive feedback hypothesis (which is inferred by the tipping point or jumping state hypothesis) to amplify tiny changes which would create a random oscillating pattern). The last major climate event of this type is called the 8200 year before present event which is a 2C cooling event that lasted for 400 years.

    This is the Greenland Ice sheet temperature data for the last 100,000 years. Can you see the cyclic abrupt changes?

    http://oceanservice.noaa.gov/education/pd/tidescurrents/media/effect_influences_3.gif


    You would not accept the assertion that now and then rocks jump up hill. There is no analytical data to support the assertion that planetary climate can or does have massive cyclic changes without a massive forcing function (a massive forcing function that is in proportion to what is observed), a physical reason for what is observed. There is no evidence for a 'smart' amplification mechanism that appears when required to create for example the Younger Dryas abrupt climate change event. The Younger Dryas is an immense climate change (the planet went from interglacial warm to glacial cold during the Younger Dryas with 70% of the cooling occurring in less than a decade. The Younger Dryas lasted for 1200 years. Why so long? Why did the 8200 year before present abrupt cooling event last 400 years?) which is an example of cyclic, abrupt, immense climate change. The Younger Dryas is a type of cyclic abrupt forcing function that is capable of and that does terminate interglacial periods.

    The paleo data supports the assertion that there is an unknown cyclic forcing function (the forcing mechanism changes as there are small, medium, and super large changes in the paleo record which all have a periodicity of 1470 years) that causes, is the physical reason, for what is observed. Part of the reason as to why the massive forcing function has not been found, is that multiple zombie theories have filled the void.

    The Younger Dryas abrupt climate change event occurred when solar summer insolation at 65N was maximum. That fact and more than a dozen other observations/anomalies/paradoxes indicates that the 'hypothesis' that summer solar insolation at 65N is somehow responsible for, 'part of the solution' for what causes the glacial/interglacial cycle is also a zombie theory.

    Solar summer insulation at 65N is currently the same as it was 20,000 years ago during the coldest period of the last 100,000 year glacial period.

    This is the Antarctic sheet temperature data for the last 420,000 years. Interglacial periods end abruptly not gradually. A fourth zombie 'theory' which has no connection with the paleo data is that interglacial periods end gradually rather than rapidly. As the graph indicates and multiple peer reviewed papers state based on analysis of data, interglacial periods end abruptly.

    http://www.climate4you.com/images/VostokTemp0-420000 BP.gif

    http://www.pik-potsdam.de/~stefan/Publications/Journals/rahmstorf_grl_2003.pdf


    http://www.geo.arizona.edu/palynology/geos462/8200yrevent.html


    http://www.esd.ornl.gov/projects/qen/transit.html [Broken]

    Sudden climate transitions during the Quaternary

     
    Last edited by a moderator: May 7, 2017
  6. Aug 31, 2015 #5

    Dale

    Staff: Mentor

    Thread closed pending moderation.

    EDIT: the OP was banned for infractions incurred elsewhere on the forum, so this thread will remain closed
     
    Last edited: Sep 9, 2015
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