YDIH Bibliography: 15 Years of Skeptical Literature
The scientific community’s ongoing rejection of the Younger Dryas impact hypothesis (YDIH) is demonstrated by the large and growing volume of skeptical literature documented in this bibliography of eighty publications. Note: some of these sources have been incorrectly cited by some authors as support for the YDIH. Quotes are provided (in red) to show otherwise.
VOLUME 28 NUMBER 1 2023 SKEPTIC.COM
2007
Reimold, W.U. The Impact Crater Bandwagon:(Some problems with the terrestrial impact cratering record). Meteoritics & Planetary Science, 42(9) 1467-1472, (2023). “The popularity of impact cratering and the rapid invoking of this process without proper supporting evidence is further exemplified by … the report of a controversial hypothesis that impact of a large comet or asteroid could have been responsible for the demise of the Clovis culture in North America. ”
2008
Buchanan, B., Collard, M., & Edinborough, K. Paleoindian demography and the extraterrestrial impact hypothesis. Proc. Natl. Acad. Sci. U.S.A. 105, 11651–11654 (2008). “The results of the analyses were not consistent with the predictions of extraterrestrial impact hypothesis.”
Collard, M., Buchanan, B., & Edinborough, K. Reply to Anderson et al. , Jones, Kennett and West, Culleton, and Kennett et al. : Further evidence against the extraterrestrial impact hypothesis. Proc. Natl. Acad. Sci. U.S.A. 105, E112-E114 (2008). “…the 181 dates from the Southeast provide another reason to reject the ET impact hypothesis.”
Haynes, C.V. Younger Dryas “black mats” and the Rancholabrean termination in North America. Proc. Natl. Acad. Sci. U.S.A. 105, 6520–6525 (2008). “…I remain skeptical of the ET impact hypothesis as the cause of the YD onset and the megafaunal extinction.”
Pinter, N. & Ishman, S.E. Impacts, mega-tsunami, and other extraordinary claims. GSA Today 18, 37 (2008). “Carl Sagan once said that ‘extraordinary claims require extraordinary evidence’; we argue that these impacts do not meet that standard.”
van der Hammen, T. & van Geel, B. Charcoal in soils of the Allerød-Younger Dryas transition were the result of natural fires and not necessarily the effect of an extra-terrestrial impact. Netherlands Journal of Geosciences 87, 359–361 (2008). “We argue that there is no need to invoke an extraterrestrial cause to explain the charcoal in the fossilized soils.”
2009
Boslough, M.B. Problems with the Younger Dryas Boundary (YDB) Impact Hypothesis (abstract). American Geophysical Union Fall Meeting, December 14-18 (2009). “We argue that the physics of fragmentation, dispersion, and airburst is not consistent with the hypothesis; that observations are no more compatible with impact than with other causes; and that the probability of the scenario is effectively nil.”
Fiedel, S.J. What Caused the Megafaunal Extinctions? The Case Against Bolide Impact. Journal of Cosmology 2, 286-288 (2009). “The impact hypothesis, and the data marshaled in support, do not offer a complete or compelling explanation of the century-long Younger Dryas onset...”
Gill, J.L., Williams, J.W., Jackson, S.T., Lininger, K.B. & Robinson, G.S. Pleistocene Megafaunal Collapse, Novel Plant Communities, and Enhanced Fire Regimes in North America. Science 326, 1100–1103 (2009). “Human impacts remain plausible, but the decline predates Younger Dryas cooling and the extraterrestrial impact event proposed to have occurred 12,900 years ago.”
Gillespie, R. Desperately seeking a cosmic catastrophe 12,900 B.P. Journal of Cosmology 2, 295-299 (2009). “A catastrophic bolide impact at 12.9 ka has been proposed by Firestone and colleagues to explain Younger Dryas cooling and megafauna extinction in North America. Radiocarbon dating of carbon spherules supposedly formed during this ET event do not support the hypothesis.”
Hamilton, M.J. & Buchanan, B. Archaeological and Paleobiological Problems with the Case for the Extraterrestrial Younger Dryas Impact Event, Journal of Cosmology 2, 289-292 (2009). “…to date there does not seem to be any convincing empirical evidence from either the archaeological or paleobiological records to support some of the basic predictions of the hypothesis.”
Kaiser, K., Hilgers, A., Schlaak, N., Jankowski, M., Kühn, P., Bussemer, S., & Przegiętka, K.. Palaeopedological marker horizons in northern central Europe: characteristics of Lateglacial Usselo and Finow soils. Boreas 38, 591–609 (2009). “Recent claims that the Usselo soil represents an event layer from rapid aeolian sedimentation caused by an extraterrestrial impact is rejected.”
Kerr, R.A. Did the mammoth slayer leave a diamond calling card? Science 323, 26 (2009). “So once again the advocates of a Younger Dryas impact are hearing that they have yet to make their case. ‘They're a long way from being able to use [the nanodiamonds] to justify an impact,’ says impact mineralogist Bevan French of the Smithsonian National Museum of Natural History in Washington, D.C. ‘I don't think you've got a unique impact marker’ in nanodiamonds.”
Marlon, J.R., Bartlein, P.J., Walsh, M.K., Harrison, S.P., Brown, K.J., Edwards, M.E., Higuera, P.E., Power, M.J., Anderson, R.S., Briles, C., Brunelle, A., Carcaillet, C., Daniels, M., Hu, F.S., Lavoie, M., Long, C., Minckley, T., Richard, P.J.H., Scott, A.C., Shafer, D.S., Tinner, W., Umbanhowar, C.E., & Whitlock, C. Wildfire responses to abrupt climate change in North America. Proc. Natl. Acad. Sci. U.S.A. 106, 2519–2524 (2009). “We also test the hypothesis that a comet impact initiated continental-scale wildfires at 12.9 ka; the data do not support this idea, nor are continent-wide fires indicated at any time during deglaciation.”
Paquay, F.S., Goderis, S., Ravizza, G., Vanhaeck, F., Boyd, M., Surovell, T.A., Holliday, V.T., Haynes, C.V., & Claeys, P. Absence of geochemical evidence for an impact event at the Bølling–Allerød/Younger Dryas transition. Proc. Natl. Acad. Sci. U.S.A. 106, 21505–21510 (2009). “Our data show no evidence of an extraterrestrial (ET)-PGE enrichment anomaly in any of the investigated depositional settings investigated across North America and in one section in Belgium. The lack of a clear ET-PGE signature in this sample suite is inconsistent with the impact of a large chondritic projectile at the Bølling–Allerød/Younger Dryas transition.”
Surovell, T., Holliday, V.T., Gingerich, J.A.M., Ketron, C., Haynes Jr., C.V., Hilman, I., Wagner, D.P., Johnson, E., & Claeys, P. An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis. Proc. Natl. Acad. Sci. U. S. A. 106, 18155-18158 (2009). “We were unable to reproduce any results of the Firestone et al. study and find no support for Younger Dryas extraterrestrial impact.”
2010
Boslough, M.B. Problems with the Younger Dryas Boundary (YDB) Impact Hypothesis (abstract). American Quaternary Association (AMQUA) Biennial Meeting, Laramie, Wyoming, Aug. 13-15 (2010). “The YDB impact explanation is extremely improbable, in addition to being physically impossible.”
Broecker, W.S., Denton, G.H., Edwards, R.L., Cheng, H., Alley, R.B. and Putnam, A.E. Putting the Younger Dryas cold event into context. Quaternary Science Reviews, 29(9-10), 1078-1081 (2010). “One might argue that a one-time event such as a catastrophic flood or even the impact of an extra-terrestrial object (Firestone et al., 2007) served to pre-trigger a YD cold episode that was destined to happen on its own. Of course, this is a possibility, but when viewed in the context of the last four terminations, cold reversals equivalent to the YD seem to be integral parts of global switches from glacial to interglacial climate. No one-time catastrophe is required.”
Carlson, A. E. What Caused the Younger Dryas Cold Event? Geology 38, 383–384 (2010). “…evidence for Younger Dryas-like events during earlier deglaciations precludes a unique comet forcing.”
Daulton, T.L., Pinter, N., & Scott, A.C. No evidence of nanodiamonds in Younger-Drays sediments to support an impact event. Proc. Natl. Acad. Sci. U. S. A. 37, 16043-16047 (2010). “Our results cast doubt upon one of the last widely discussed pieces of evidence supporting the YD impact hypothesis.”
French, B.M. & Koeberl, C. The convincing identification of terrestrial meteorite impact structures: What works, what doesn't, and why. Earth-Science Reviews 98, 123-170 (2010). “…the case for [Younger Dryas] meteorite impact cannot be accepted on the basis of the results so far presented. The alleged impact criteria are neither reliable nor diagnostic, and there are many unresolved geological problems associated with the proposed ‘airburst’ impact mechanism”
Haynes, C.V., Lauretta, D.S., & Ballenger, J.A.M. No confirmation of impact at the lower Younger Dryas boundary at Murray Springs, AZ. Proc. Natl. Acad. Sci. U. S. A. 107, E106 (2010). “…we find no compelling evidence for an extraterrestrial impact or cosmic catastrophe at the Murray Springs Clovis site…”
Haynes, C.V., Boerner, J., Domanik, K., Lauretta, D., Ballenger, J., & Goreva, J. Reply to Firestone et al.: The Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact. Proc. Natl. Acad. Sci. U.S.A. 107, 4010–4015, (2010). “From the data presented here we find no compelling evidence for a cosmic catastrophe at the Murray Springs Clovis site.”
Holliday, V.T. & Meltzer, D.J. The 12.9ka impact hypothesis and North American Paleoindians. Curr. Anthropol., 575-585 (2020). “…an extraterrestrial impact is an unnecessary solution for an archaeological problem that does not exist.”
Kerr, D. 'Mammoth-Killer' Nothing More Than Fungus and Bug Poop. Science, 17 June (2010). “Proponents of the idea that an exploding comet wiped out mammoths, giant sloths, and other megafauna 12,900 years ago have pointed to unusual organic debris in the soil from this period—debris, they say, that could have formed only in extreme wildfires raging across North America. But in a new study, a team argues that this debris is just fungal remains and bug poop.”
Meltzer, D.J. & Holliday, V.T. Would North American Paleoindians have noticed Younger Dryas age climate changes? Journal of World Prehistory 23, 1-41 (2010). “…conditions during the Younger Dryas interval may not have measurably added to the challenge routinely faced by Paleoindian groups...”
Morrison, D. Did a Cosmic Impact Kill the Mammoths? Skeptical Inquirer 34, May/June (2010). “… there are two clues that something is amiss with the YD impact hypothesis. First is the 2006 book The Cycle of Cosmic Catastrophes, which formulates the YD hypothesis within the context of catastrophist pseudoscience… Second is the absence of confirming or supporting papers by scientists who were not members of the original team.”
Paquay, F. S., Goderis, S., Ravizza, G. & Claeys, P. Reply to Bunch et al.: Younger Dryas impact proponents challenge new platinum group elements and osmium data unsupportive of their hypothesis. Proc. Natl. Acad. Sci. U.S.A. 107 (2010). “…the Younger Dryas (YD) sections do not remotely resemble analyses of sediments from known impact horizons.”
Scott,A.C., Pinter, N., Collinson, M.E., Hardiman, M., Anderson, R.S., Brain, A.P.R., Smith, S.Y., Marone, F., Stampanoni, & M. Fungus, not comet or catastrophe, accounts for carbonaceous spherules in the Younger Dryas “impact layer”. Geophys. Res. Lett. 37, L14302 (2010). “The results here echo those of other studies that either (1) have been unable to duplicate the evidence presented in support of a YD impact… or (2) have found that the impact proponents asserted catastrophic and extraterrestrial sources for material of terrestrial and/or everyday origins.”
2011
Dalton, R. Comet Theory Comes Crashing to Earth. Pacific Standard, 14 May (2011). “Kennett seems fixated on the Younger Dryas, Broecker added, ‘He won’t listen to anyone. It’s almost like a religion to him.’”
Pinter, N., Scott, A.C., Daulton, T.L., Podoll, A., Koeberl, C., Anderson, R.S., & Ishman, S.E. The Younger Dryas impact hypothesis: A requiem. Earth-Science Reviews 106, 247-264 (2011). “Throughout the arc of this hypothesis, recognized and expected impact markers were not found, leading to proposed YD impactors and impact processes that were novel, self-contradictory, rapidly changing, and sometimes defying the laws of physics.”
Tian, H., Schryvers, D., & Claeys, P. Nanodiamonds do not provide unique evidence for a Younger Dryas impact. Proc. Natl. Acad. Sci. U. S. A. 108, 40–44 (2011). “…the present variety of crystalline structures observed in the black Younger Dryas boundary in Lommel does not provide sufficient evidence to conclude an exogenic impact as the origin of these structures.”
2012
Blaauw, M., Holliday, V.T., Gill, J.L., & Nicoll, K. Age models and the Younger Dryas Impact Hypothesis. Proc. Natl. Acad. Sci. U.S.A. 109 (2012). “…the layer investigated by Israde-Alcántara et al. is not demonstrably or securely dated to the start of the YD, and indeed according to the evidence presented is most likely several millennia older.”
Boslough, M., Nicoll, K., Holliday, V., Daulton, T.L., Meltzer, D., Pinter, N., Scott, A.C., Surovell, T., Claeys, Ph., Gill, J., Paquay, F., Marlon, J., Bartlein, P., Whitlock, C., Grayson, D., & Jull, T. Arguments and Evidence against a Younger Dryas Impact Event. pp. 13-26. In: Giosan, L.; D.Q. Fuller; K. Nicoll; R. Flad and P.D. Clift. (editors) Climates, Landscapes and Civilizations. Geophysical Monographs Series, 198, American Geophysical Union, Washington, D. C. (2012). “Even in the absence of counterevidence, we consider the Firestone et al. (2007) impact hypothesis to be fatally flawed because it violates physical conservation laws and is inconsistent with conventional understanding of impact physics.”
Boslough, M. Inconsistent impact hypotheses for the Younger Dryas. Proc. Natl. Acad. Sci. U.S.A., 109 (2012). “…the impact proposed by Israde-Alcántara et al. cannot have caused the widespread environmental, paleontological, and archeological effects that Firestone et al. were attempting to explain and is not consistent with the original YD impact hypothesis.”
Daulton, T.L. Suspect cubic diamond “impact” proxy and a suspect lonsdaleite identification. Proc. Natl. Acad. Sci. U.S.A. 109 (2012). “Israde-Alcántara et al., sharing many of the coauthors of Kennett et al. and Kurvatov et al., also reported lonsdaleite in purported YD-aged lake sediments in Mexico. This identification is problematic...”
Gill, J.L., Blois, J.L., Goring, S., Marlon, J.R., Bartlein, P.J., Nicoll, K., Scott, A.C., & Whitlock, C. Paleoecological changes at Lake Cuitzeo were not consistent with an extraterrestrial impact. Proc. Natl. Acad. Sci. U.S.A. 109 (2012). “We believe there are flaws in both the interpretation of the paleoecological evidence reviewed by Israde-Alcántara et al. and in its application in testing the YDIH.”
Hardiman, M., Scott, A.C., Collinson, M.E., & Anderson, R.S. Inconsistent redefining of the carbon spherule “impact” proxy. Proc. Natl. Acad. Sci. U. S. A. 109 (2012). “…we note that a nontrivial number of the purported impact proxies and/or their allied interpretations originally presented in support of a YD extraterrestrial event have either disappeared from the YDIH discourse or, like CSp, changed significantly from the original descriptions of the same evidence. We note with interest, for example, that two other forms of carbon evidence (which also purportedly contained impact-related nanodiamonds) put forward by proponents of the YDIH—glassy carbon and carbon “elongates”—now seem to have joined the former.”
Pigati, J.S., Latorre, C., Rech, J.A., Betancourt, J.L., Martínez, K.E., & Budahn, J.R. Accumulation of impact markers in desert wetlands and implications for the Younger Dryas impact hypothesis. Proc. Natl. Acad. Sci. U.S.A. 109, 7208–7212, (2012). “Our data clearly show that elevated concentrations of some of the markers put forth by Firestone et al. as evidence of an ET impact event, specifically iridium in bulk and magnetic sediments, magnetic spherules, and titanomagnetite grains, are common within or at the base of black mats, regardless of age or location. These results suggest that the markers are likely concentrated by processes inherent to wetland systems and are not the result of a catastrophic impact event.”
Rick, T. C., Wah, J. S. & Erlandson, J. M. Re-evaluating the origins of late Pleistocene fire areas on Santa Rosa Island, California, USA. Quat. res. 78, 353–362 (2012). “Our results show that fire was a component of late Pleistocene Channel Island ecology prior to and after human colonization of the islands, with no clear evidence for increased fire frequency coincident with Paleoindian settlement, extinction of pygmy mammoths, or a proposed Younger Dryas impact event.”
van Hoesel, A., Hoek, W.Z., Braadbaart, F., van der Plicht, J., Pennock, G.M., & Drury, M.R. Nanodiamonds and wildfire evidence in the Usselo horizon postdate the Allerød–Younger Dryas boundary. Proc. Natl. Acad. Sci. U. S. A. 109, 7648–7653 (2012). “Our analysis thus provides no support for the Younger Dryas impact hypothesis.”
2013
Boslough, M., Harris, A.W., Chapman, C. & Morrison, D. Younger Dryas impact model confuses comet facts, defies airburst physics. Proc. Natl. Acad. Sci. U. S. A., 110 (2013). “One of the major criticisms of the hypothesis has been the lack of any physics-based model for the hypothesized event. Wittke et al. attempt to remedy this flaw by including a section entitled “Preliminary Impact Model.” Their model diverges significantly from the original but still provides no physics-based argument and demonstrates a misunderstanding of comets, as well as the physics of airbursts.”
Boslough, M. Faulty protocols yield contaminated samples, unconfirmed results. Proc. Natl. Acad. Sci. U. S. A., 110 (2013). “One microspherule was dated and yielded a radiocarbon age of 207 ± 87 y BP. This result suggests that A. West’s protocols and sample preparation methods do not eliminate contaminants that are unrelated to the YDB or to an impact. Unfortunately, no samples from the LeCompte et al. study are available for distribution to test for this possibility.”
Boslough, M. Greenland Pt anomaly may point to noncataclysmic Cape York meteorite entry. Proc. Natl. Acad. Sci. U. S. A., 110 (2013). “There is no reason to favor the Pt event as the trigger of the YDB climate change or its putative consequences. The simplest explanation is to associate the anomaly with a local noncataclysmic event that is independently known to have taken place, and that would have produced Pt-rich fallout: the Cape York meteorite fall.”
Boslough, M. Impact conclusions are a restatement of assumptions with literature misinterpretations. Sandia National Laboratories, SAND 2013-10324J (2013). “M. LeCompte--who is also coauthor of Wu et al.--has refused to make his samples available to independent researchers, withheld the details of his experimental protocol, and failed to reveal the identity of all the contributors associated with the cited study.”
Holliday, V.T. & Miller, D.S. The Clovis landscape, Paleoamerican Odyssey, 221-245 (2013). “…environmental data presented in this paper for ~13.0k further shows that there is no paleoenvironmental evidence for any sort of “cosmic catastrophe”at that time. An extraterrestrial impact producing the sort of continental-scale destruction of the natural and human environment that has been proposed should show up as a distinct marker in geomorphic, biological, and archaeological records at and just after ~12.9k cal yr BP, but it clearly does not.”
Lajeunesse, P. St‐Onge, G., Locat, J., Duchesne, M.J., Higgins, M.D., Sanfaçon, R., & Ortiz, J., . The Corossol structure: A possible impact crater on the seafloor of the northwestern Gulf of St. Lawrence, Eastern Canada. Meteorit Planet Sci 48, 2542–2558 (2013). “This structure has therefore never been “provisionally dated to 12.9 cal. ka BP” as stated in Wu et al. The results presented here now clearly provide evidence that the crater was formed prior to Quaternary glaciations.”
Ives, J.W., & Froese, D. The Chobot site (Alberta, Canada) cannot provide evidence of a cosmic impact 12,800 y ago. Proc. Natl. Acad. Sci. U.S.A. 110 (2013) “We see no support for the assertion of an age ‘of no less than 12.8 ka’ based on ‘archaeological stratigraphy’ and find compelling evidence to the contrary. The Chobot site cannot be compared with the well-documented geoarchaeological findings at locations such as Murray Springs, nor can it provide the clear evidence required to support the impact hypothesis.”
Petaev, M.I., Huang, S., Jacobsen, S.B., Zindler, A., 2013. Large Pt anomaly in the Greenland ice core points to a cataclysm at the onset of Younger Dryas. Proc. Natl. Acad. Sci. U.S.A. 110, 12917–12920 (2013).“Such a source could have been a highly differentiated object like an Ir-poor iron meteorite that is unlikely to result in an airburst or trigger wide wildfires proposed by the YDB impact hypothesis.”
Petaev, M.I., Huang, S., Jacobsen, S.B., & Zindler, A. Reply to Boslough: Is Greenland Pt anomaly global or local? Proc. Natl. Acad. Sci. U.S.A. 110 (2013). “Besides providing additional arguments against the Pt depositing event as a cause of the Younger Dryas cooling, Boslough’s letter raises an important question about the scale of this event.”
van Hoesel, A., Hoek, W.Z., van der Plicht, J., Pennock, G.M., & Drury, M.R. Cosmic impact or natural fires at the Allerød–Younger Dryas boundary: a matter of dating and calibration. Proc. Natl. Acad. Sci. U. S. A. 110 (2013). “Wittke et al. present evidence of a major cosmic impact at the onset of the Younger Dryas (YD) episode, including some markers found in the top of the well-known Usselo marker horizon (UH). This finding is contrary to our extensive radiocarbon dating effort from this horizon…”
2014
Bement, L.C., Madden, A.S., Carter, B.J., Simms, A.R., Swindle, A.L., Alexander, H.M., Fine, S. and Benamara, M., 2014. Quantifying the distribution of nanodiamonds in pre-Younger Dryas to recent age deposits along Bull Creek, Oklahoma Panhandle, Proc. Natl. Acad. Sci. U. S. A. 111(5), 1726-1731 (2014). “Although the high concentration of nds at the YDB along BC may support the ET hypothesis, the high concentration of nds identified in late Holocene deposits indicates such levels are not unique to the YDB.”
Holliday, V.T., Surovell, T., Meltzer, D.J., Grayson, D.K., & Boslough, M. The Younger Dryas impact hypothesis: A cosmic catastrophe. J. Quat. Sci. 29, 515-530 (2014). “The basic physics in the YDIH is not in accord with the physics of impacts nor the basic laws of physics. No YD boundary (YDB) crater, craters or other direct indicators of an impact are known. Age control is weak to non-existent at 26 of the 29 localities claimed to have evidence for the YDIH. Attempts to reproduce the results of physical and geochemical analyses used to support the YDIH have failed or show that many indicators are not unique to an impact nor to ∼12.9k cal a BP. The depositional environments of purported indicators at most sites tend to concentrate particulate matter and probably created many 'YDB zones'. Geomorphic, stratigraphic and fire records show no evidence of any sort of catastrophic changes in the environment at or immediately following the YDB. Late Pleistocene extinctions varied in time and across space. Archeological data provide no indication of population decline, demographic collapse or major adaptive shifts at or just after ∼12.9 ka. The data and the hypotheses generated by YDIH proponents are contradictory, inconsistent and incoherent.”
Meltzer, D.J., Holliday, V.T., Cannon, M.D., & Miller, D.S.. Chronological evidence fails to support claims for an isochronous widespread layer of cosmic impact indicators dated to 12,800 years ago. Proc. Natl. Acad. Sci. U. S. A. 111, E2162-E2171 (2014). “The YDIH fails the critical chronological test of an isochronous event at the YD onset, which, coupled with the many published concerns about the extraterrestrial origin of the purported impact markers, renders the YDIH unsupported. There is no reason or compelling evidence to accept the claim that a cosmic impact occurred ∼12,800 y ago and caused the Younger Dryas.”
Reimold, W.U., Ferrière, L., Deutsch, A., & Koeberl, C. Impact controversies: Impact recognition criteria and related issues. Meteoritics & Planetary Science 49, 723-731 (2014). “The hype about a Younger Dryas impact catastrophe continues to split the scientific community, despite absence of any proper evidence supporting an impact hypothesis. New questionable reports of geological structures alleged to be of impact origin have been published—mainly in online journals that do not appear to follow specialist peer review and adherence to best editorial practice, but unfortunately also in some reputable journals. ”
Surovell, T. Supplementary Information: A Response to LeCompte et al. (2012), in Holliday, V.T., Surovell, T., Meltzer, D.J., Grayson, D.K., and Boslough, M. The Younger Dryas impact hypothesis: A cosmic catastrophe. J. Quat. Sci. 29, 525-530 (2014). “Surovell et al. (2009) found that microspherules were regularly found in non-YDB samples and occasionally in YDB samples as well, but in zero of seven sites was a strong peak in spherules uniquely associated with the YDB. In other words, the presence, absence, and relative abundance of magnetic microspherules appears to have little to do with extraterrestrial impact.”
van Hoesel, A. The Younger Dryas climate change: was it caused by an extraterrestrial impact? Utrecht University Repository (2014). “In order to prove that a single impact event (multiple airbursts or just one impactor) caused the Younger Dryas, all markers found must be deposited synchronous and date to the onset of the Younger Dryas. This synchronous-site requirement presents several challenges to the Younger Dryas impact hypothesis. Most critically, there is an age discrepancy of up to two centuries between sites where Younger Dryas impact markers have been found. If the markers are not of the same age, they cannot be related to the same event. In conclusion, there is no convincing evidence for the occurrence of one or more climate changing extraterrestrial impacts or airbursts at the onset of the Younger Dryas…”
van Hoesel, A., Hoek, W.Z., Pennock, G.M., & Drury, M.R. The Younger Dryas impact hypothesis: a critical review. Quat. Sci. Rev. 83, 95-114 (2014). “…the evidence used by for example Firestone et al. to support the YD impact hypothesis these criteria are not met.”
2015
Boslough, M., Nicoll, K., Daulton, T.L., Scott, A.C., Claeys, P., Gill, J.L., Marlon, J.R., & Bartlein, P.J. Incomplete Bayesian model rejects contradictory radiocarbon data for being contradictory. Proc. Natl. Acad. Sci. U. S. A. 112, (2015). “More data on other presumed markers would indeed be useful, and we hope that sample splits will be made available to us for independent radiocarbon dating. Nevertheless, Kennett et al. have no logical bases to exclude our data from their Bayesian model or dismiss our conclusions that their previous age models were inaccurate. It is because they reject dates that contradict their model that Kennett et al. arrive at a conclusion that contradicts ours.”
Holliday, V.T. Problematic dating of claimed Younger Dryas boundary impact proxies. Proc. Natl. Acad. Sci. U. S. A. 112, (2015). “The data presented above and elsewhere provide evidence for multiple horizons with “impact proxies” at times other than the YDB, and raise doubts about the utility of the statistical manipulations to address the dating of the YDB, which can be no better than the data on which they are based.”
Thy, P., Willcox, G., Barfod, G.H., & Fuller, D.Q. Anthropogenic origin of siliceous scoria droplets from Pleistocene and Holocene archaeological sites in northern Syria. J. Archaeol. Sci. 54, 193–209 (2015). “We therefore conclude that melting of building earth in ancient settlements can occur during fires reaching modest temperatures. There is no evidence to suggest that siliceous scoria droplets result from very high temperature melting of soil and are the result of a cosmic event.”
van Hoesel, A., Hoek, W.Z., Pennock, G.M., Kaiser, K., Plümper, O., Jankowski, M., Hamers, M.F., Schlaak, N., Küster, M., Andronikov, A.V., & Drury, M.R. A search for shocked quartz grains in the Allerød-Younger Dryas boundary layer. Meteoritics & Planetary Science 50, 483-498 (2015). “Although the PDFs in the grain should have been formed during an extraterrestrial impact, if it occurred, a single shocked quartz grain cannot be unequivocally used to support the Younger Dryas impact hypothesis.”
2016
Holliday, V.T., Surovell, T., & Johnson, E. A blind test of the Younger Dryas impact hypothesis. PLoS ONE 11, e0155470 (2016). “The results of analyses of blind samples collected at the Lubbock Lake site to test the YD impact hypothesis produced no evidence of an extraterrestrial impact at the YDB.”
2017
Broecker, W.S., A Broecker Brief: An extraterrestrial impact at the onset of the Younger Dryas? (2017). “…I don’t for a minute believe that this impact did in the mammoths and the Clovis people… I realize that this subject is distasteful to many because of the early false claims.”
Daulton, T.L., Amari, S., Scott, A.C., Hardiman, M., Pinter, N., & Anderson, S. Comprehensive analysis of the nanaodiamond evidence relating to the Younger Dryas Impact Hypothesis. J. Quat. Sci. 32, 7-34 (2017). “We find no evidence for lonsdaleite in YDB sediments and find no evidence of a spike in nanodiamond concentration at the YDB layer to support the impact hypothesis.”
Daulton, T.L., Amari, S., Scott, A., Hardiman, M., Pinter, N., & Anderson, R.S. Did nanodiamonds rain from the sky as Woolly Mammoths fell in their tracks across North America 12,900 years ago? Microscopy & Microanalysis. 23, 2278–2279 (2017). “…we determined that measurements of a nanodiamond abundance spike at the YDB reported by, and other impact proponents that used similar techniques, are critically flawed and are not credible."
Scott, A.C., Hardiman, M., Pinter, N.P., Anderson, R.S., Daulton, T.L., Ejarque, A., Finch, P., & Carter-Champion, A. Interpreting palaeofire evidence from fluvial sediments; A case study from Santa Rosa Island, California with implications for the Younger Dryas Impact Hypothesis. J. Quat. Sci. 32, 35-47 (2017). “…we find no evidence in Arlington Canyon for an extra-terrestrial impact or catastrophic impact-induced fire.”
2018
Gramling, C. Why won’t this debate about an ancient cold snap die? Science News June 26, (2018). “Indeed, no craters have been found dating to the Younger Dryas, and the landscape of North America — the likely ground zero for such an impact, proponents say — has been pretty thoroughly checked out.”
2019
Boslough, M. Crater Discovery Story Flawed by Premature Link to Speculative Impact Hypothesis. Skeptical Inquirer, 43, March/April (2019). “This impact hypothesis contradicted mainstream science in virtually every field it touched, including astronomy, impact physics, archaeology, paleontology, geology, paleoecology, paleoclimatology, and even crystallography. ”
Green, C. E. Investigating the origin of a Greenland ice core geochemical anomaly near the Bølling-Allerød/Younger Dryas boundary. Masters Thesis (2019). “The event resulting in the Pt spike occurred ~60 years after GS-1 cooling, and was therefore not the primary trigger.”
Kaiser, K., Hilgers, A., Schlaak, N., Jankowski, M., Kühn, P., Bussemer, S., & Przegiętka, K. Palaeopedological marker horizons in northern central Europe: characteristics of Lateglacial Usselo and Finow soils. Boreas 38, 591–609 (2019). “Recent claims that the Usselo soil represents an event layer from rapid aeolian sedimentation caused by an extraterrestrial impact is rejected.”
Schaetzl, R. J., Sauck, W., Heinrich, P. V., Colgan, P. M. & Holliday, V. T. Commentary on Klokočník, J., Kostelecký, and Bezděk, A. 2019. The putative Saginaw impact structure, Michigan, Lake Huron, in the light of gravity aspects derived from recent EIGEN 6C4 gravity field model. Journal of Great Lakes Research 45, 1003–1006 (2019). “They used highly interpretive and questionable gravity-based arguments for an extraterrestrial impact in the Saginaw Bay region of Michigan at ≈12.9 ka. The authors explain the lack of evidence for an impact structure by suggesting that any such meteorite would have impacted an ice sheet that covered the region at that time. However, the Laurentide Ice had long-since retreated from the region, rendering this explanation moot.”
2020
Cheng, H., Zhang, H., Spötl, C., Baker, J., Sinha, A., Li, H., Bartolomé, M., Moreno, A., Kathayat, G., Zhao, J., Dong, X., Li, Y., Ning, Y., Jia, X., Zong, B., Ait Brahim, Y., Pérez-Mejías, C., Cai, Y., Novello, V.F., Cruz, F.W., Severinghaus, J.P., An, Z., & Edwards, R.L. Timing and structure of the Younger Dryas event and its underlying climate dynamics. Proc. Natl. Acad. Sci. U.S.A. 117, 23408–23417 (2020). “Based on this paleoanalog and the preponderance of geochronological data, we contend that the YD Impact Hypothesis remains untenable…”
Holliday, V.T., Bartlein, P.J., Scott, A.C., & Marlon, J.R. Extraordinary biomass-burning episode and impact winter triggered by the Younger Dryas cosmic impact similar to 12,800 Years Ago, Parts 1 and 2: A Discussion. J. Geol. 128, 69-94 (2020). “The authors assume that impacts triggered widespread fires, but the evidence for such a link between extraterrestrial impacts and wildfires is weak. ”
Jorgeson, I.A., Breslawski, R.P., & Fisher, A.E. Radiocarbon simulation fails to support the temporal synchroneity requirement of the Younger Dryas impact hypothesis. Quat. res. 96, 123–139 (2020). “These results suggest that a central requirement of the Younger Dryas Impact Hypothesis, synchronous global deposition of a YDB layer, is extremely unlikely, calling into question the Younger Dryas Impact Hypothesis more generally.”
Sun, N., Brandon, A. D., Forman, S. L., Waters, M. R. & Befus, K. S. Volcanic origin for Younger Dryas geochemical anomalies ca. 12,900 cal B.P. Sci. Adv. 6 (2020). “Multiple occurrences above and below the anticipated YD basal boundary layer bring into question the single impact theory for the YD climate event.”
2021
Cheng, H. et al. Reply to Stuchlík et al.: The Younger Dryas onset at 12.87 ky B.P. is still justified if the Laacher See eruption is considered. Proc. Natl. Acad. Sci. U.S.A. 118 (2021). “We suggested that ‘a possible extraterrestrial impact event at ∼12,820 B.P. inferred by Pt-anomaly in the GISP2 ice core appears to lag the initial onset of the YD by ∼50 y without apparent disruption on the hydroclimate trend, suggesting that this event might not be the trigger for the YD onset’”
Sun, N., Brandon, A.D., Forman, S.L., & Waters, M.R. Geochemical evidence for volcanic signatures in sediments of the Younger Dryas event. Geochimica et Cosmochimica Acta 312, 57–74 (2021). “The results are inconsistent with the extraterrestrial hypothesis and support instead an episodic and volcanic origin for the observed geochemical anomalies at the Debra L. Friedkin and Hall’s Cave sites, Texas.”
2022
Boslough, M. Age of Greenland Crater Deals Blow to Younger Dryas Impact Hypothesis. Skeptical Inquirer, 46, July/August (2022). “YDB impact enthusiasts, who had argued that their hypothesis should be promoted to a ‘theory,’ were disappointed. Devotees had considered the Hiawatha Crater their smoking gun despite expert opinion. Their hopes now hinge primarily on their own definition of impact markers that contradicts longstanding mineralogic and geochemical criteria established by impact specialists.”
Fiedel, S.J. Initial human colonization of the Americas, redux. Radiocarbon, 64, 845-897 (2022). “The bolide and its effects have been characterized inconsistently from one paper to the next, which makes this hypothesis difficult to refute…”
Jorgeson, I.A., Breslawski, R.P., & Fisher, A.E. Comment on “The Younger Dryas impact hypothesis: A review of the evidence”, by Martin B. Sweatman (2021), Earth-Science Reviews 218, 103677. Earth-Science Reviews 225, 103892 (2022). “Sweatman's review of the Younger Dryas Impact Hypothesis (YDIH) makes three critiques of our research, two of which are based on misstatements about our methods, and the third of which is true but irrelevant. Correcting these misstatements demonstrates that the chronological record is inconsistent with the claim of synchroneity fundamental to the YDIH.”
2023
Boslough, M. Apocalypse! Skeptic 28, (2023). “Virtually all experts, working independently in the relevant fields, who have stated their opinions about the YDIH, have expressed skepticism. The negative scientific consensus that emerged very quickly after the first peer-reviewed publication introduced the YDIH 15 years ago has not changed.”
Holliday, V.T., Daulton, T.L., Bartlein, P.J., Boslough, M.B., Breslawski, R.P., Fisher, A.E., Jorgeson, I.A., Scott, A.C., Koeberl, C., Marlon, J. and Severinghaus, J. Comprehensive refutation of the Younger Dryas Impact Hypothesis (YDIH). Earth-Science Reviews, 104502, (2023). “Evidence and arguments purported to support the YDIH involve flawed methodologies, inappropriate assumptions, questionable conclusions, misstatements of fact, misleading information, unsupported claims, irreproducible observations, logical fallacies, and selected omission of contrary information.”
Related Blog Posts
It’s Time to Retract the Sodom Airburst Paper
Lost Diamonds and Disappearing Impact Evidence
Advocates of Younger Dryas Impact Hypothesis (YDIH) “Independently” Evaluated Their Own Results
The Fringe Roots of the Younger Dryas Impact Hypothesis: Part 1
Related Videos
National Geographic/BBC animation of contact airburst (2006)
Younger Dryas impact hypothesis, NOVA (2009)
Modeling a Comet Airburst, NOVA (2009)
PubPeer
Several peer-reviewed papers on the YDIH and related subjects have been called into question on PubPeer. These criticisms have led to corrections and published comments. Here is a partial list.
Original YDIH paper: Firestone et al., 2007
YDIH Nanodiamonds in Greenland: Kurbatov et al., 2010
YDIH “independent” evaluation: LeCompte et al., 2012
Sodom & Gomorrah airburst paper: Bunch et al., 2021