Younger Dryas - likely the result of meteor impact

  1. jim mcnamara

    jim mcnamara 1,565
    Science Advisor
    Gold Member

    Origin and provenance of spherules and magnetic grains at the Younger Dryas boundary
    Yingzhe Wu, Mukul Sharma, Malcolm A. LeCompte, Mark N. Demitroff, and Joshua D. Landis
    PNAS 2013 ; published ahead of print September 5, 2013, doi:10.1073/pnas.1304059110
    From the overview:
    The takeaway is that a large meteor impact in Quebec showered a very large area in Northeastern North America with hot debris. The debris is at the exact boundary of the onset of the Younger Dryas. If this impact did not entirely cause the Younger Dryas cooling, it certainly is the most likely major player in the event. (My interpretation).

    Mukul Sharma, one of the researchers, said as much in an article earlier:
  2. jcsd
  3. Greg Bernhardt

    Staff: Admin

    Interesting, thanks for sharing Jim!
  4. It is astonishing how long it takes to solve holistic scientific problems. The analysis goes off into left field or runs in circles.

    There is no formal summary of all of the data and the competing theories related to the problem. Anomalies and paradoxes are ignored (There must be a physical explanation for everything that has happened and will happen.) Theories are not compared to each other. The people writing and reviewing the papers show obvious bias. The system rewards unending paper writing rather than problem solving.

    1) Impact as the cause of the burn marks is Extraordinarily Unlike as it Requires Multiple Separate Impacts

    An astrophysicist researcher commented on a PBS program that discussed the Younger Dryas comet/meteoroid theory that it is impossible for a single comet or a single meteoroid impact to cause the observed burn marks on two different continents at multi latitudes (nine locations). The observed pattern of nine locations with burn marks on two different continents at multiple latitudes would require multiple impacts from separate comets and/or meteoroids (eight or nine, almost no probability of one object causing multiple burn marks).

    (Think of the necessary orbital trajectory of the objects and try to image what trajectory would be required to create the observed pattern of nine locations where there were burn marks.)

    The astrophysicist then noted based on the probability of a single impact it is virtually impossible for there to be multiple impacts (eight or nine) in such a short time period.

    He also noted that the probability is further reduced as the requirement is for the burn marks with no impact crater which requires special conditions.

    2) The Younger Dryas Abrupt Cooling Period Lasted for 1200 years

    An impact to the earth will cool the earth for a few years, similar to what is observed again and again for a single major eruption. The planet resists forcing changes rather than amplifies forcing changes by an increase or decrease in clouds in the tropics. The cooling due to a major impact will last less than a decade.

    3) There are cycles of abrupt climate in the paleo record which have a periodicity of 1470 years which are called Dansgaard-Oeschger cycles and Heinrich cycles. The Heinrich cycles require a very, very strong forcing function, as they are capable of terminating an interglacial period. The Younger Dryas abrupt cooling event is a Heinrich event. What causes the Heinrich events (cycles) and the Dansgaard-Oeschger cycles that happens again and again and again. It is not impacts.

    4) There is the largest change in C14 in the Holocene at the Younger Dryas. A massive change in C14 requires either a massive change to the geomagnetic field or a very, very long abrupt change to the sun.

    The 8200-year Climate Event

  5. Evo

    Staff: Mentor

    IIRC, the younger dryas /meteor event was disproved, we had threads about it.
  6. Hello,
    The problem of what causes cyclic abrupt climate change and the glacial/interglacial cycle has not been solved. There is the unsolved scientific problem and there is a problem/issue that unsolved scientific problems are not solved.

    The analysis and solution of what caused the Younger Dryas is directly connected to the analysis of what causes the glacial/interglacial cycle. Both analyses are going in circles. The 2013 published, Impact Paper is an example to support the assertion the analysis does not converge on solving the scientific problem. There are basic fundamental problem solving techniques that are used in private industry to solve complex holistic problems that are not used in pure science.

    The analysis is not converging on finding the physical cause of abrupt cyclic climate change. The issue is not a lack of data. There are piles and piles of observations to solve the problem of what cause cyclic abrupt climate change and what causes the glacial/interglacial cycle. The physical solution to the problem is not included with the list of hypotheses/theories that is being evaluated.

    There are three urban legend forcing functions:

    1) The assertion that changes in summer insolation at 65N being the cause of the glacial/interglacial cycle is an urban legend. The Younger Dryas abrupt climate change is an example of cyclic abrupt climate change. It occurred during a period when summer insolation at 65N was at maximum. There are other examples in the paleo record of exactly the same phenomenon as the Younger Dryas. There are seven fundamental problems with the orbital changes in solar insolation at 65N which support the assertion that it is an urban legend. This disproved theory is included in every paleo climate text book.

    2) The assertion that an interruption to the North Atlantic drift current as being a possible cause for cyclic abrupt climate change is an urban legend. This disproved theory is included in every paleo climate text book and every paper that discusses the Younger Dryas event.,y.0,no.,content.true,page.1,css.print/issue.aspx
    3) Comet/asteroid impact.

    It is a fact that abrupt climate change is cyclic. The Heinrich events and the lesser Dansgaard-Oeschger cyclic warming and cooling occur along the same 1470 year series which supports the assertion that they both have the same cause. Impacts are not cyclical. Regardless an impact will cause the planet to cool for less than a decade, not 1200 years.

    The burn marks are a clue to what causes abrupt geomagnetic excursions. What caused the high temperature burn marks? It is not an impact. There needs to be a physical explanation for the burn marks.

    There is an abrupt change to the geomagnetic field (which causes the largest increase in C14 in Holocene record) that correlates with the Younger Dryas abrupt cooling event.

    The paleo record shows the geomagnetic field tilt is cyclically abruptly changing by 10 to 15 degrees. The north pole drift velocity increased, in the mid 1990s from the 15 km/yr to 55 km/yr. The geomagnetic field intensity drop also in the mid 1990's has increased from the 5%/century to 5%/decade.

    There is a current paradox that requires a physical cause. The geomagnetic field is currently dropping ten times faster than possible for a change in the liquid core. A magnetic excursion will cause the planet to cool for 1200 years. An impact will cause the planet to cool for less than decade, not 1200 years.

    This is a link to the 2013 paper.

  7. betzalel, What burn marks are you talking about?
  8. Evo

    Staff: Mentor

    Here are the opposing hypotheses.

    Read more at:

  9. Evo, there are many more papers in favor of the Firestone et al. 2007 impact hypothesis.

    Regarding citation #2, read Lecompte et al 2012 for why at least one other researcher (Todd Surovell) could not find the evidence: improper methodology.

    LeCompte, M. A., Goodyear, A. C., Demitroff, M. N., Batchelor, D., Vogel, E. K., Mooney, C., ... & Seidel, A. W. (2012). Independent evaluation of conflicting microspherule results from different investigations of the Younger Dryas impact hypothesis. Proceedings of the National Academy of Sciences, 109(44), E2960-E2969.

    Betzalel, these are not "burn marks". They are referred to by Haynes 2008 as "black mats" although some sites are not black.

    The Gothenburg Magnetic excursion (Nils Axel Morner) has been debated, as apparently it could not be reproduced. It may be valid, but I am not sure
    the excursion and fire are linked. How do you explain the Pt spike in the ice cores (Petaev et al 2013) with your hypothesis of an electrical/geomagnetic phenomenon at YDB?
  10. Evo

    Staff: Mentor

    Yes, but there are many others that show evidence to the contrary. I admit I do not know who/what to believe. I do trust your judgement on these issues, so if you are convinced of the Firestone impact hypothesis, I will re-read the other studies with more scrutiny.

  11. So....Evo, nitrate can be a combustion marker in ice cores, but it can also be from nitric acid rain following an extraterrestrial event (nitrates form
    from the dissociation of N2 in the atmosphere and O3 in the stratosphere; these nitrates rain out as nitric acid rain (Prinn and Fegley 1987)).
    Turns out that we could determine whether the nitrates were from biomass burning or shockwave nitrates by analyzing the Oxygen isotopes
    in the NO3 (nitrate). The ozone layer is enriched in 17O, and nitrates formed from that source would also be enriched in 17O (Hastings et al. 2013).
    There are other markers that can be used for biomass burning. These include acetate, formate, ammonium, oxalate and levoglucosan.
    Evo likes this.
  12. In reply to:
    The melt pulse occurred a 1000 years before the Younger Dryas event. Regardless, complete stoppage of the North Atlantic drift current will only result in winter cooling of Europe of a few degrees.

    Secondly there is no thermal haline conveyor. Wally Broeker suggested there was a thermal haline conveyor based on his assumption not based on observations and that urban legend took off and is repeated everywhere.

  13. Re: "Ten locations" that got very hot, see Haynes 2008 for a report on so called black mats in the U.S.

    There are also black mats in Venezuela, in The Netherlands, Belgium and Germany. They may be elsewhere as well.
  14. Betzalel, the hypothesized impactor could have broken into many pieces. Also the shockwave generates heat.
    The geomagnetic research is very important though.
  15. Chronos

    Chronos 10,349
    Science Advisor
    Gold Member

    Is it not feasible the younger dryas was triggered by a comet that fragemented in the atmosphere? Apologies, I just noticed NileQueen is suggesting the same possibility.

  16. There are ten burn mark sites (nine in the North America and one in Europe).

    It is not possible for a single object to 'break up' to cause the burn marks. Look at the locations where the burn marks were found.

    As noted an impact will cool the earth for less than a decade, the same as a major eruption.

    The Younger Dryas abrupt cooling event was for 1200 years. An impact cannot cause the burn marks and an impact cannot cause cooling for 1200 years.

    Lastly the cooling events are cyclic not a one of event.

    Last edited: Aug 30, 2015
  17. Betzalel, there are not "ten burn sites". There are AT LEAST 97.

    There can be a fireball from the shockwave heating of the atmosphere; look at literature on the K/T (now K/Pg) impact.
    ..."Once Chicxulub was identified, it became possible to calculate that shocked quartz had been launched into a high-angle spray from the impact. This first hot fireball blew vaporized and molten debris (including glass spherules and iridium) high above the atmosphere to be deposited last and globally as it slowly drifted downward. The larger fragments, solid and molten, were blasted outward at lower angles, but not very far, and were deposited first and locally (about 15 minutes travel time to Colorado!). At the same time, smaller fragments, including shocked quartz, were blown upward between the hot fireball and the larger fragments, and were deposited second and regionally (about 30 minutes to reach Colorado). The impact energy, for comparison with hydrogen bomb blasts, was around 100 million megatons."

    The YD was likely very wet at the beginning from ponding of water (lack of evapotranspiration), and then very dry due to increased wind.
    There was more sea ice in the North Atlantic (see for instance, Brauer et al. 2008, Increased windiness...) less or almost no evaporation from the North Atlantic, and less deposition of snow
    on the Greenland ice sheet.
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