New evidence that an extraterrestrial collision 12,800 years ago triggered an abrupt climate change for Earth

The muck that’s been accumulating at the bottom of this lake for 20,000 years is like a climate time capsule. Christopher R. Moore, CC BY-ND

Christopher R. Moore, University of South Carolina

What kicked off the Earth’s rapid cooling 12,800 years ago?

In the space of just a couple of years, average temperatures abruptly dropped, resulting in temperatures as much as 14 degrees Fahrenheit cooler in some regions of the Northern Hemisphere. If a drop like that happened today, it would mean the average temperature of Miami Beach would quickly change to that of current Montreal, Canada. Layers of ice in Greenland show that this cool period in the Northern Hemisphere lasted about 1,400 years.

This climate event, called the Younger Dryas by scientists, marked the beginning of a decline in ice-age megafauna, such as mammoth and mastodon, eventually leading to extinction of more than 35 genera of animals across North America. Although disputed, some research suggests that Younger Dryas environmental changes led to a population decline among the Native Americans known for their distinctive Clovis spear points.

Conventional geologic wisdom blames the Younger Dryas on the failure of glacial ice dams holding back huge lakes in central North America and the sudden, massive blast of freshwater they released into the north Atlantic. This freshwater influx shut down ocean circulation and ended up cooling the climate.

Some geologists, however, subscribe to what is called the impact hypothesis: the idea that a fragmented comet or asteroid collided with the Earth 12,800 years ago and caused this abrupt climate event. Along with disrupting the glacial ice-sheet and shutting down ocean currents, this hypothesis holds that the extraterrestrial impact also triggered an “impact winter” by setting off massive wildfires that blocked sunlight with their smoke.

The evidence is mounting that the cause of the Younger Dryas’ cooling climate came from outer space. My own recent fieldwork at a South Carolina lake that has been around for at least 20,000 years adds to the growing pile of evidence.

A collision from space would leave its mark on Earth. Vadim Sadovski/Shutterstock.com

What would an Earth impact leave behind?

Around the globe, scientists analyzing ocean, lake, terrestrial and ice core records have identified large peaks in particles associated with burning, such as charcoal and soot, right at the time the Younger Dryas kicked in. These would be natural results of the cataclysmic wildfires you would expect to see in the wake of Earth taking an extraterrestrial hit. As much as 10% of global forests and grasslands may have burned at this time.

Looking for more clues, researchers have pored through the widely distributed Younger Dryas Boundary stratigraphic layer. That’s a distinctive layer of sediments laid down over a given period of time by processes like large floods or movement of sediment by wind or water. If you imagine the surface of the Earth as like a cake, the Younger Dryas Boundary is the layer that was frosted onto its surface 12,800 years ago, subsequently covered by other layers over the millennia.

In the last few years, scientists have found a variety of exotic impact-related materials in the Younger Dryas Boundary layer all over the globe.

These include high-temperature iron and silica-rich tiny magnetic spheres, nanodiamonds, soot, high-temperature melt-glass, and elevated concentrations of nickel, osmium, iridium and platinum.

While many studies have provided evidence supporting the Younger Dryas impact, others have failed to replicate evidence. Some have suggested that materials such as microspherules and nanodiamonds can be formed by other processes and do not require the impact of a comet or asteroid.

White Pond has been part of this landscape for 20,000 years or more. Christopher R. Moore, CC BY-ND

A view of 12,800 years ago from White Pond

In the southeastern United States, there are no ice cores to turn to in the quest for ancient climate data. Instead, geologists and archaeologists like me can look to natural lakes. They accumulate sediments over time, preserving layer by layer a record of past climate and environmental conditions.

White Pond is one such natural lake, situated in southern Kershaw County, South Carolina. It covers nearly 26 hectares and is generally shallow, less than 2 meters even at its deepest portions. Within the lake itself, peat and organic-rich mud and silt deposits upwards of 6-meters thick have accumulated at least since the peak of the last ice age more than 20,000 years ago.

Collecting sediment cores from White Pond in 2016. Christopher R. Moore, CC BY-ND

So in 2016, my colleagues and I extracted sediment from the bottom of White Pond. Using 4-meter-long tubes, we were able to preserve the order and integrity of the many sediment layers that have accumulated over the eons.

The long sediment cores are cut in half in order to extract samples for analysis. Christopher R. Moore, CC BY-ND

Based on preserved seeds and wood charcoal that we radiocarbon dated, my team determined there was about a 10-centimeter thick layer that dated to the Younger Dryas Boundary, from between 12,835 and 12,735 years ago. That is where we concentrated our hunt for evidence of an extraterrestrial impact.

We were particularly looking for platinum. This dense metal is present in the Earth’s crust only at very low concentrations but is common in comets and asteroids. Previous research had identified a large “platinum anomaly” – widespread elevated levels of platinum, consistent with a global extraterrestrial impact source in Younger Dryas layers from Greenland ice cores as well as across North and South America.

Most recently, the Younger Dryas platinum anomaly has been found in South Africa. This discovery significantly extends the geographic range of the anomaly and adds support to the idea that the Younger Dryas impact was indeed a global event.

Volcanic eruptions are another possible source of platinum, but Younger Dryas Boundary sites with elevated platinum do not have other markers of large-scale volcanism.

More evidence of an extraterrestrial impact

In the White Pond samples, we did indeed find high levels of platinum. The sediments also had an unusual ratio of platinum to palladium.

Both of these rare earth elements occur naturally in very small quantities. The fact that there was so much more platinum than palladium suggests that the extra platinum came from an outside source, such as atmospheric fallout in the aftermath of an extraterrestrial impact.

My team also found a large increase in soot, indicative of large-scale regional wildfires. Additionally, the amount of fungal spores that are usually associated with the dung of large herbivores decreased in this layer compared to previous time periods, suggesting a sudden decline in ice-age megafauna in the region at this time.

Photomicrograph of Sporormiella – fungal spores associated with the dung of megaherbivores – from White Pond. Angelina G. Perrotti, CC BY-ND

While my colleagues and I can show that the platinum and soot anomalies and fungal spore decline all happened at the same time, we cannot prove a cause.

The data from White Pond are, however, consistent with the growing body of evidence that a comet or asteroid collision caused continent-scale environmental calamity 12,800 years ago, via vast burning and a brief impact winter. The climate change associated with the Younger Dryas, megafaunal extinctions and temporary declines or shifts in early Clovis hunter-gatherer populations in North America at this time may have their origins in space.

A White Pond sediment core is like a timeline of the stratigraphic layers. What researchers found in each layer provides hints of climate and environment at that time. Shutterstock.com/Allen West/NASA/Sedwick C (2008) PLoS Biol 6(4): e99/Martin Pate/Southeast Archaeological Center, CC BY-ND

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Christopher R. Moore, Archaeologist and Special Projects Director at the Savannah River Archaeological Research Program and South Carolina Institute of Archaeology and Anthropology, University of South Carolina

This article is republished from The Conversation under a Creative Commons license. Read the original article.

HT/Jerry HH

233 thoughts on “New evidence that an extraterrestrial collision 12,800 years ago triggered an abrupt climate change for Earth

  1. This is how actual science is done.
    Painstaking.
    Slow.
    Laborious.
    Thorough.
    Not flashy.
    Most importantly field collected Data (in this case with refined C14 dating methods and microscopic examinations).

    Not circular logic computer simulations, where the desired conclusion forms the model coded assumptions and their output is called a “line of evidence.”
    Not tree rings that a pre-selected for hockey sticks.

    • Yes, it is refreshing to have a study which is not driven by the need to include CO2 or other human factors in the death of mega-fauna or climate variations.

      The only thing which struck me was the pocket knife. Are they really using such a crude implement to cut the core sample ? That must lead to some blurring and cross contamination of adjacent layers, probably in a rather irregular way.

      I would have thought that something like a wire cheese cutter method would be better, using a continuous piece of wire, drawn through in a uniform and consistent manner, would be better.

        • They carefully shave the cores when they arrive for sampling after they were shipped frozen to ensure they don’t blurr the lines.

      • Greg, there are two knives visible in the second photo. The one in the distance is a pocket knife, but it is not clear that it has a cutting blade extended as opposed to a pick or a file or screwdriver. The knife nearest the camera in this photo is one having either a fixed or folding blade, but would not normally qualify as a “pocket knife” and it does not appear to be soiled.

        One cannot rule out the possibility that either or both of those knives were used for a purpose OTHER THAN cutting core samples . . . for example cutting plastic or foil to cover samples. Take notice of (a) the plastic bag and its contents on the table, and (b) the two rectangular cardboard containers of some (assumed) rolled, but otherwise-undefined, material in the white bucket resting on the floor to the left of the table in the shot.

        Finally, I serious doubt that the scientists need to cut out individual slices of the cores once the metal coring tubes have been band-sawed or wire-sawed in half longitudinally, as has obviously been done in the photo. They very likely need only several tenth’s of a gram of material, each sample extracted from less than 5 mm of axial core length, to do the chemical and microscopic analysis and to date that sample to high precision.

        Notice, in particular, in the third-from-the-left tube cross-section, near its mid-length, the 20 or so regularly-spaced “notches” along the right edge of that tube. I suspect those are locations where the tip of the blade of the knife nearest of camera was used to carefully extract the small amounts of material. Knowing their stuff, I have no doubt that the blade tip was carefully cleaned by the scientists between sample extractions (and this likely explains the roll of paper towels visible on the table).

        And, yes, I do have too much free time on my hands.

      • Palladium in soil is soluble and removed while platinum is not. As such the Pt:Pd ratio is not diagnostic.

        • Palladium is scientifically classified as a nobel metal, meaning that is has high resistant to corrosion and oxidation in moist air. Palladium is only very slightly soluble in liquid water if it contains chloride ions (stated as “trace” solubility), forming palladium chloride.

          Palladium is usually found associated with platinum: “There are six Platinum Group Metals that, although rare, are often found together in a mineral deposit. They include platinum, palladium, rhodium, iridium, ruthenium and osmium . . . Approximately 50% of global palladium production comes from platinum mines.”—source: https://resourceworld.com/platinum-palladium-review/

          The scientists looking at the mud cores from White Pond (aka “lake”) stated that the level of platinum was elevated with respect to the level of palladium, and NOT that the palladium levels around the time of Younger Dryas were depressed relative to normal. Therefore, those scientists are effectively using palladium as a control to show that the elevated platinum levels are NOT reflecting platinum concentration from a natural (terrestrial) source, whereby the Pt:Pd ratio should remain approximately constant no matter what process is postulated explain a natural mechanism for concentration of the platinum at the time of Younger Dryas.

          The Pt:Pd ratio is indeed diagnostic, but does not—as the above article clearly states—prove a cause.

          Simple, if you understand the article’s statements.

    • This is how actual science is done.

      I disagree. This is hypothesis-driven science. The kind of science that got us in the anthropogenic global warming disaster. They pick a hypothesis and then they set out to prove it, selecting the evidence that supports it, ignoring the evidence against it, and disregarding alternative explanations, all while ignoring the null hypothesis.

      Skepticism is our only weapon to defend against getting stuck in a wrong paradigm for decades. The Younger Dryas Impact (YDI) hypothesis is highly controversial because:
      1. There is no clear indisputable evidence of an important impact at the time.
      2. Even if there was an important impact there is no clear evidence that it caused the cooling.

      The author of the article acts more like a used-car salesman than a scientist properly trained in the scientific method. The YDI hypothesis has been oversold since the beginning, the same as the CO2 hypothesis of global warming. Big claims based on little evidence.

      Let’s see. What we have is very good evidence of an abrupt (not sudden) cooling over a few decades, and the severe cooling already provides an explanation for many of the phenomena attributed to the impact.
      – Land becomes less productive causing a decrease in the supportable biomass of fauna. Add an efficient hunter and you’ve got megafaunal extinctions.
      – The cooling leads to a drying through decreased precipitation which is the cause of the fires. Every rapid cooling of the Holocene is reflected in charcoal records. See Florescu et al., 2019 “Holocene rapid climate changes and ice-rafting debris events reflected in high-resolution European charcoal records.”
      – The decrease in pollen and the change in pollen species is also one of the consequences of the cooling.

      Then we have a lack of substantive evidence for the impact. The platinum increase is not a meteorite signature unlike the iridium. Abrupt cooling results in an abrupt increase in the ice load over certain parts of the crust, leading to an increase in volcanic activity as it happened during the LIA.

      The null hypothesis, that the Younger Dryas was not caused by an impact, is intact. Alternative explanations are possible and there are no shortage of them. There are proponents of reduced solar activity, proponents of severe reduction in the Atlantic Meridional Overturning Circulation due to a sudden influx of fresh meltwater, proponents of severe volcanic activity, and proponents of the Younger Dryas being the last of the Heinrich events that are spaced around 5-6 thousand years:
      https://i.imgur.com/oumF89c.png

      In evidence-driven science you don’t discard an explanation until the evidence tells you to do so. But explanations without strong supporting evidence, like the YDI, should be disfavored. Getting a lake sediment core and selling that it supports the YDI when in reality it doesn’t add anything new is not how science should be done. It is a symptom of the science malady that has gotten us into the mess we are. It is overselling. It is supporting an attractive hypothesis without clear evidence and going to the media to get the attention and funding they wouldn’t get otherwise.

      • It starts with painstakingly collected data. Analyzed. The really hard work. Endless days of long hours in the lab doing the same analysis, a repetition that is mind numbing.
        Where you are wrong Javier is you’ve been jaded by so many bad clisci ignoring uncertainty you now think anyone with a favored hypothesis means they are ignoring alternative explanations.

        • anyone with a favored hypothesis means they are ignoring alternative explanations.

          But they are ignoring alternative explanations. The title of the article is WRONG. “New evidence that an extraterrestrial collision 12,800 years ago triggered an abrupt climate change for Earth.” There is absolutely nothing that was not known already in that study. Regardless of the amount of work it is just a “Me too in my spot” article being severely oversold in a non-scientific venue. Nothing in the article supports the YDI hypothesis. Everything can be explained by processes that do not require an impact.

          Big claims, little evidence is the hallmark of bad science.

          • “.” There is absolutely nothing that was not known already in that study.”

            wrong.

            evidence found at a new site is evidence that the cause was probably not local.

            as for the null hypothesis.. there is none. This is abduction

          • wrong.

            Ahh Mosher, taking the opposite point of view to yours is my main reassurance of being right.

            The platinum spike at multiple locations had already been reported by Moore himself:
            Moore et al., 2017. “Widespread platinum anomaly documented at theYounger Dryas onset in North American sedimentary sequences”
            In Chile
            Pino et al., 2019 “sedimentary record from patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8 ka”
            In South Africa
            Thackeray et al., 2019. “The Younger Dryas interval at Wonderkrater (South Africa) in the context of a platinum anomaly”
            And in a variety of European locations.

            All the other coeval changes, charcoal, vegetation, spores, nodules and so on, have been found at multiple locations.

            The only thing that it is new is that it is at White pond, South Carolina. So we already knew that the presented evidence is not local. Your level of knowledge of the matter under discussion is inadequate as usual.

            As for:

            as for the null hypothesis.. there is none.

            That’s your opinion. The null hypothesis is that the cause is a different one to the one you are proposing. Science works on the falsifiability principle. No amount of evidence can demonstrate that the YD was caused by an impact. One just has to demonstrate that the competing hypotheses lack the capability to explain the YD. Either that or find evidence that disproves that the impact took place. But in this case it is unnecessary so far, as there is no evidence that the impact took place. A metallic meteorite is required to explain the Pt spike, yet a metallic meteorite leaves a crater. Unless it hits water or ice, but then it does not produce a Pt spike. So we need a ghost meteorite capable of producing a Pt spike and have an explosive burst in the atmosphere at multiple locations to produce global fires, global extinctions and global cooling. Aliens appear to be required.

            Occam is rolling over the floor. My skeptic-sense is tingling.

          • The null hypothesis is that the cause of the YD was the same as for the Older Dryas and Middle Dryas cold snaps during the last glacial termination, and for similar intervals in previous terminations. And as for the numerous Heinrich events during glaciations.

            That is, cold fresh meltwater pulses or iceberg armadas which melt at sea, with the same climatic effect. The evidence for this is overwhelming abundant. Hence the null hypothesis not only can’t be rejected, but is as certain to be the case is possible in geology and paleoclimatology.

          • There is absolutely nothing that was not known already in that study.

            Huh? So you’re saying that particular S Carolina lake already had sediment cores taken, analyzed and results reported before this study? This study just repeated it?

          • No. What I am saying is that they repeated what others have done at different places in a new place and found exactly the same the others found.

            Repeating the same experiment and getting the same result can hardly be considered new evidence. But some people are very good at overselling their re-confirmation. Then people that know little about the issue believe something important was discovered.

          • Javier, on July 28 at 3:31 am, posted “Nothing in the article supports the YDI hypothesis. Everything can be explained by processes that do not require an impact.”

            Then please explain, outside of an extraterrestrial object impacting Earth, both the anomalous enrichment of platinum and the anomalous increase in the Pt/Pd ratio in the core layer samples reliably dated to be around the time of the Younger Dryas?

            Going further, do you assert that the Alvarez-team finding of Ir enrichment at the K-T boundary— associated with geological evidence of an asteroid impact (the Chicxulub crater remnants)—does not, after all, “require an impact”?

            FWIW, I do take issue with this statement in the above article’s third-from-last paragraph, referring to platinum and palladium: “Both of these rare earth elements occur naturally in very small quantities.” While Pt and Pd are indeed relatively rare on Earth’s surface (as elemental concentration), they are not scientifically classified as “rare earth” elements.

          • Gordon,

            Iridium isn’t platinum. While flood basalt Kilauea does, few volcanoes release much iridium, which is very rare on Earth. Ir is a much better space origin marker than Pt.

          • Then please explain, outside of an extraterrestrial object impacting Earth, both the anomalous enrichment of platinum and the anomalous increase in the Pt/Pd ratio in the core layer samples reliably dated to be around the time of the Younger Dryas?

            Tankersley et al., 2018. Positive Platinum anomalies at three late Holocene high magnitude volcanic events in Western Hemisphere sediments

            do you assert that the Alvarez-team finding of Ir enrichment at the K-T boundary— associated with geological evidence of an asteroid impact (the Chicxulub crater remnants)—does not, after all, “require an impact”?

            No I don’t. They’ve got iridium, and they’ve got the crater. The K/T impact says nothing about the YDIH.

          • The odds against an impact large enough to cause mass extinction in the past 15,000 years are enormous.

            The end Cretaceous impact was by a body estimated at 11-81 km in diameter. Lacking a crater or any other useful information, the alleged size of the supposed YD impactor is simply a WAG. But let’s imagine greater than 5000 m. How often does an asteroid or comet of this size hit Earth?

            Amelin, Gusiakov and Lyapidevskaya (2013) estimate around 20 million years, on average.

            Estimates of the impact frequency of cosmic bodies on the Earth

            https://bulletin.iis.nsk.su/files/article/amelin.pdf

            Mass extinction events (d > 5000 m, E > 107 Mt TNT). Interval > 20 Ma.

            Which just happens to hit the LIS during its melting process, so as not to leave a crater. Right.

          • Not a single giant asteroid, but the potential a swarm of dozens to hundreds of stony objects in the 100 to 500+ meter diameter range. Tunguska ++ range. Stony asteroids airburst, and impart all their energy into heat, light (flash), and shock wave. High airburst = No crater. Tunguska is believed to have come out of the Taurid stream. The witnesses said it came out from the sun, which matches the direction the Taurids come from in June. The Earth at 12.9KYA could have passed through the Taurid Resonant Swarm, and caught a concentration of objects recently separated from a much larger parent body. The original comet body entered the inner solar system about 20KYA and began disintegration… leaving Comet 2P/Encke, and hordes of smaller objects from gravel on up . There would have been lots more objects, and more larger objects 12.9 KYA than there would be now.

          • Javier,

            Thank you for the response, but it—together with the Tankersley et al. [2018] article that you linked—do nothing to address the key point that the elevated Pt:Pd ratio found in the White Pond mud samples dating to the approximate time of Younger Dryas is indicative of an extraterrestrial object impact.

            As to the absence of discovery of an impact crater (or its remnants) correlated to the estimated age of Younger Dryas, one straightforward explanation is that postulated asteroid fragmented during atmospheric entry, depositing its energy and platinum into the atmosphere, but not causing any significant crustal upset.

            I only used the KT-boundary/Ir concentration to show that geological layers displaying elemental enrichment have been useful in the past for indicating that extraterrestrial object “impacts” do indeed happen with worldwide consequences on climate.

          • Gordon,

            the elevated Pt:Pd ratio found in the White Pond mud samples dating to the approximate time of Younger Dryas is indicative of an extraterrestrial object impact.

            Indicative falls very very short from demonstrating. Science is not about finding explanations but about finding evidence. And extraordinary claims require extraordinary evidence.

            And even if it was demonstrated that there was an impactor we would still had the problem of demonstrating that it was responsible for the cooling. Correlation does not imply causation. Does this sound familiar to you? We use it all the time to say there is no evidence that CO2 is responsible for most of the warming.

          • John Tillman

            You claimed that Hawaiian basalts have elevated iridium. Can you provide me with a citation for that claim? What mineral(s) is the iridium associated with in the basalts?

            Typically, alluvial deposits of Platinum Group Minerals (PGM) derived from ultramafic sources, that are of mineable grade, have roughly equal concentrations of ferro-platinum and osmiridium (in addition to many other PGMs). That is due, in part, to osmiridium being harder and more resistant to chloride-complexing than ferro-platinum. Primary dunite deposits containing chromatites with 10 PPM PGMs would be considered ore grade. What kind of concentrations are in the basalts?

          • John,
            Thank you for the links. As your second link notes, “Since iridium enrichments have not previously been observed in volcanic emissions, …” I didn’t think that the reference could be found easily. Since you made the statement, I presumed you would be familiar with the source.

        • Javier : ” I disagree . This is hypothesis driven science ……drying through decreased precipitation …is the cause of the fires ….we have a lack of substantive evidence for the impact . The platinum increase is not a meteorite signature unlike the iridium .Abrupt cooling results in an abrupt increase in the ice load over certain parts of the crust leading to an increase in volcanic activity as it happened during the LIA ” .So Javier starts off disparaging hypothesis driven science only to fabricate an implausible hypothesis himself and conveying the impression he did not even read the article …The author emphasized the dissonant ratio of palladium to platinum at the YD boundary layer. The enriched platinum must have originated from space probably in the form of a comet debris bombardment event consisting of surface impacts and high altitude bolides ..He also stated that ” sites with elevated platinum do not have other markers of large scale volcanism ” Try comprehending what the author actually wrote Javier ..The Carolina lake sediment core data corroborates evidence collated from around the world including enhanced platinum deposits in the northern and southern hemispheres …If the Younger Dryas cataclysm was volcanic these same deposits and ice layers would be caked in tephra and sulphate.. The null , albeit extravagant hypothesis is yours .

          • Er, allow me to remind you that the YDIH predates the discovery of the platinum spike by 7 years, so yes it is hypothesis-driven science of the worst kind, since it has been plagued by false claims and irreproducible results, and has morphed several times, changing from a comet to a meteorite, sometimes with an impact site, sometimes with an airburst.

            There are lots of hypotheses about the cause of the YD. The YDIH is severely lacking in evidence.

          • The platinum almost certainly did not originate from space, although there could have been a random slightly elevated background infall of ET debris on either side of the YD by the hundred of years in which putative excursions occur.

            But by far the best and most parsimonious explanation is natural terrestrial fluctuation. This hypothesis is supported by the fact that as the ice burden fell, more volcanoes erupted.

            The least likely explanation is one big impact, the odds against which, as below, are around 2000 to one.

      • Nothing wrong with “hypothesis-driven science”. It’s in fact the essence of any real scientific method since research questions are not randomly formed. You seem to be confused with regards to the differences between hypothesis, theory and model? However there’s no simple formula to determine which research questions are worthy to formulate and translate into doing research and testing. Even measurements are corresponding to some kind of model, some kind of parameterization.

        The Achilles heal of modern science: how bias and group dynamics can grow into a filter and value system when determining validity of a model or theory. This is a danger to all scientific topics where the outcome has many political and ideological relations. Compare this with intelligence gathering by government agencies. No matter the professional approach: blind spots will occur since people are not machines, they are bias containers, if anything.

        • Nothing wrong with “hypothesis-driven science”.

          There is a lot wrong with hypothesis-driven science. The hypothesis is selected before there is sufficient evidence supporting it in order to claim first (or early) authorship over the hypothesis and afterwards scientists supporting it engage in confirmation bias and hypothesis espousing. If sufficient support is obtained for the hypothesis it leads to the reigning paradigms of Kuhn in which the dominant consensus supporters engage in opposition suppression tactics like we see with AGW hypothesis.

          Feynman expressed it very clearly when he said:
          However, it is rather remarkable how we can have some ideas which will last so long. One of the ways of stopping science would be only to do experiments in the region where you know the law. But experimenters search most diligently, and with the greatest effort, in exactly those places where it seems most likely that we can prove our theories wrong. In other words we are trying to prove ourselves wrong as quickly as possible, because only in that way can we find progress.

          If you make a hypothesis it must be derived from evidence and only so you and others can try to prove it wrong. The YDIH was made by Firestone based on false and insufficient evidence and its supporters have engaged in the usual confirmation bias. Of course that doesn’t mean that the hypothesis is wrong, but it is just one of many hypotheses and not a particularly well supported one.

          • Javier–you say that there is a lot wrong with hypothesis driven science.
            I’m of an age where any mention of Wegener and his theory was met with almost universal derision by the faculty in my geology department. What was Wegener’s theory if not hypothesis driven. Even after indisputable evidence was in, some of those frozen brains were stuck with their ingrained beliefs. As they say, science advances one generation at a time. There may not be enough evidence yet to change minds, but the science is not static, more evidence could possibly still be found, and then what do you do.

          • Actually John, Wegener hypothesis was evidence-driven science of the best kind. Alfred Wegener presented a consilience of evidence from multiple disciplines in what probably amounts to one of the best evidence-supported hypotheses of all time. By comparison Darwin had a lot less evidence in his favor.
            This figure has some of it:
            https://i.imgur.com/Oe1Y88k.png
            a) Continental platforms match one another (geographical evidence). Wegener’s own drawing. b) Geological formations extend from one continent to others when in joint position, like the Caledonian Belt (geological evidence). c) Fossil distribution from 335-175 Ma can only be explained if 5 continents were together (paleontological evidence). d) Cratons distribution in South America and Africa also match. e) Glacial deposits distribution from Late Paleozoic (Karoo) glaciation can only be explained if continents had a very different disposition and India was in the Southern Hemisphere (climatological evidence).

            There was also biological evidence from the distribution of certain animal groups in South America and Africa that have a common origin.

            The only question is why such a hypothesis so well supported by evidence could have been rejected for over 40 years. The answer is that not enough weight was given to the evidence and too much to the lack of mechanism. In the end we are defeated by our failure to consider our own ignorance.

          • Javier : ” I disagree . This is hypothesis driven science ” [ John is quite right – there is nothing wrong with scientific hypotheses at all ] ….And what does Javier respond with ?…. Hypothesis driven opinionated speculative pseudoscience for which he provides scant evidence ..You foolishly contradicted yourself coupled with ad hominem abuse of the author and upon realizing that refused to acknowledge your embarrassing remarks resorting instead to condescending posturing : ” Er , allow me to remind you that ..” .I need reminding ?. So what if the platinum enrichment was discovered years after the YD impact hypothesis ?..Thats called corroborative evidence . Furthermore , the author mentioned the amplified presence of iridium you admitted was a ” meteorite signature” which once again suggests you have not comprehended the article at all or have some tendentious ” scrambling ” discrediting agenda . Pretentiously citing Feynman and Kuhn impresses no one. .Indeed your cognitive dissonance arguments are the antithesis of scientific rationality and not dissimilar to the psychological disposition of anthropogenic climate change alarmists . You have now doubled down with more of the same verbose nonsense : ” There is a lot wrong with hypothesis driven science . The hypothesis is selected before there is sufficient evidence supporting it ….If you make a hypothesis it must be derived from evidence ” …..You mean like this bizarre hypothesis : ” Abrupt cooling results in an abrupt increase in the ice load over certain parts of the crust leading to an increase in volcanic activity as it happened during the LIA ” You wrote that. Yet the author of this article clearly emphasized that ” the sites with elevated platinum do not have other markers of large scale volcanism ” ..So where is the evidence for this fringe hypothesis you selected with little ” sufficient evidence supporting it ” Javier ?. The risible doublethink is certainly apparent . As for you John Tillman , if the ” best and most parsimonious explanation is natural terrestrial fluctuation ” ….specifically the alleged ” fact that as the ice burden fell [ Javier believes the vulcanism surged as the ice expanded..Why dont you swap notes ? ] more volcanoes erupted ” , where is the necessarily abundant evidence for enormous volcanic tephra and sulphate in the soil and ice layers coinciding with the platinum corresponding to the YD boundary ? …Parsimonious is the operative word …The only logical source of the anomalous platinum deposits is cometary or asteroid material ..Occams Razor applies with the Younger Dryas impact hypothesis as the most plausible : elevated platinum , iridium, osmium and nickel , nanodiamonds , spherules , soot from massive burning …The archaeo-astronomical research outlining the progressive disintegration of the Taurid progenitor comet – and other evidence for Late Holocene impacts and cosmic dust influxes – correlates with this evidence ,completely refuting your ” one in 1600 ” chances of an impact assumptions ..Indeed you do not even seem to realize this is predicated on the standard obsolete ” Single Large Impact” paradigm that ignores the coherent catastrophism model .

      • Javier:

        You said “The platinum increase is not a meteorite signature unlike iridium”

        Then what is your explanation for the sudden increase in these rare metals (platinum and palladium)?

        • I fail to see the logic that don’t having an explanation for a Pt spike makes the YDIH more probable. It is a form of the argumentum ad ignorantiam fallacy. You don’t have an alternative explanation, therefore my explanation is right.

          What is missing is the evidence that the Pt spike has an extraterrestrial origin, and the evidence that even if the Pt spike is from an impact, that impact caused the YD.

          Compared to the YDIH, the CO2 hypothesis looks well supported.

          • Javier, I like the way you think. There indeed is a difference between looking for an impact crater due to an unexplained iridium signature, rather than looking for a platinum signature presupposing there was an impact.

            Considering the preservation of 50,000 year old Meteor Crater in Arizona, logic suggests that a 12,800 year old impact crater large enough to have caused the Younger Dryas would have been found long before platinum anomalies–if we looked for one instead of looking for platinum.

            But the impact still might someday prove to be true, of course. That satellite imagery hasn’t provided an impact crater is pushing it back, however.

          • Javier:

            In spite of what you say, your not having any alternate explanation for the Platinum spike DOES make the probability of a large meteoric impact more probable.

            Especially since it would have triggered extensive volcanism, whose SO2 emissions would have cooled the planet.

            And the the later rapid warming, when the volcanism abated, and their SO2 aerosols settled out, probably within less than 20 years, for a given volcano.

          • In spite of what you say, your not having any alternate explanation for the Platinum spike DOES make the probability of a large meteoric impact more probable.

            A second logical fallacy. Not having an alternate explanation reflects only on my ignorance and does not alter in any way the probability of a large meteoric impact.

            I think you have trouble understanding what science is about. It is not about coming with plausible explanations but about finding evidence that distinguishes between alternate explanations, and being very strict about what the evidence actually demonstrates.

            The Pt spike does not demonstrate a cosmic impact. It only demonstrates an increase in atmospheric Pt of unknown origin. If I am correct the Pt spike is not found in any Antarctic core, so its global nature is disputed.

            Especially since it would have triggered extensive volcanism, whose SO2 emissions would have cooled the planet. And the the later rapid warming, when the volcanism abated, and their SO2 aerosols settled out, probably within less than 20 years, for a given volcano.

            This is just narrative and has nothing to do with science. Where is the evidence that it is what happened? The YD lasted about 1100 years and came after a warmer period of about 1900 years interrupted by two severe cooling episodes of about 200-300 years. The Older Dryas and the Intra-Allerød Cold Period. Similar abrupt warming and abrupt cooling events have taken place during the Last Glacial Period. They are known as Daansgard-Oeschger events and Heinrich events. Each one had a warming starting the event and a cooling ending it, exactly as the Bølling-Allerød period. The cooling from the Younger Dryas is special because it is closer to us and took place when the interglacial warming had already started. Do we look for meteorite impacts for every Daansgard-Oeschger event and Heinrich event? It looks like a daunting fruitless task.

            Occam says that what we are observing is similar to what has happened in the past multiple times. That is the basis for the Uniformitarianism that Charles Lyell introduced to great success. If you want to be Catastrophic you better come up with damn good evidence. A rare metal spike won’t cut it.

          • Any platinum excursions around the time of the YD are purely coincidental. Volcanic eruptions produce them frequently:

            https://phys.org/news/2018-07-platinum-evidence-ancient-volcanic-related-climate.html

            Space dust and rocks fall in all the time, often to burn up in the atmosphere, their remnant then being carried around the world. Sometimes slightly larger bodies hit the ground, enriching certain spots in ET minerals and elements.

            Correlation isn’t causation, and in this case there’ precious little if any even correlation.

          • Len Werner,
            maybe this impact body (if there was one) landed in the sea? All the others are supposed to have landed on land. Isn’t the earth’s surface 70% covered with water?

          • Javier : ” I fail to see the logic that dont [ sic ] having an explanation for a Pt spike makes the YDIH more probable ”
            I fail to see the logic in your foolish self contradiction although I can understand why you refuse to admit it . Let me remind you : ” I disagree . This is hypothesis driven science …..There is a lot wrong with hypothesis driven science …In other words we are trying to prove ourselves wrong as quickly as possible ”

            Javiers dubious hypothesis driven ‘science’ : ” The cooling leads to a drying through decreased precipitation which is the cause of the fires … The platinum increase is not a meteorite signature unlike the iridium . Abrupt cooling results in an increase in the ice load over certain parts of the crust leading to an increase in volcanic activity as it happened during the LIA ” …..” You dont have an alternative explanation therefore my explanation is right ”

            You actually departed from hypothetical speculation to assuming decreased precipitation at the onset of the Younger Dryas boundary [ for which you provide no evidence whatsoever ] is fact : ” is the cause of the fires ” …Not possibly …Not perhaps – “is the cause ” …….” Therefore my explanation is right ” he wrote . That is a narcissistic delusion. So much for seeking to prove yourself ” wrong as quickly as possible ” . In fact you have now exceeded the strict empirical and rationalist limitations you pretended to set for yourself and others. . You also contradicted yourself again in another post : ” I wonder why catastrophic explanations have such a strong appeal to people and are so popular ” ?. Like your increased volcanic activity hypothesis ?..Is Joe Biden your ghostwriter Javier ?

            It has been explained to you and others here that a research paper published in March of this year – ” Evidence of Cosmic Impact at Abu Hureyra ,Syria at the Younger Dryas Onset [ 12 .8 ka ] : High Temperature Melting at 2200 C ” Nature Communications – has indeed discovered distinctive a suite of impact elements that cannot be attributed to volcanism including elevated iridium [ You said yourself iridium was a meteorite signature ] ,cobalt , chromium , FE silicides and abnormally high temperature melt-glass .. This latest research has not been rebutted and disproven..

            nature.com/articles/s41598-020-60867-w

          • This group supposes that the (Eifel Hot Spot) Laacher See Eruption of c. 12.9 Ka triggered the YD. But this hypothesis suffers from the same insurmountable problem as the debunked YDIH, ie that there is no need for any ET or terrestrial cause for the cold spell besides melting of the ice sheets, as observed so many times previously:

            Evaluating the link between the sulfur-rich Laacher See volcanic eruption and the Younger Dryas climate anomaly

            https://cp.copernicus.org/articles/14/969/2018/cp-14-969-2018.pdf

            The authors’ summary of the meltwater explanation:

            “A common explanation for the YD involves meltwaterinduced weakening of Atlantic Meridional Overturning Circulation (AMOC) (Berger, 1990; Alley, 2000; Broecker et al., 2010; Johnson and McClure, 1976; Schenk et al., 2018). Initial support for this theory included elevated δ18O values in Gulf of Mexico sediment dating from the early YD (implying that meltwater was rerouted elsewhere) (Broecker et al., 1988; Flower and Kennett, 1990; Teller, 1990). The meltwater was originally proposed to have travelled to the North Atlantic via the St Lawrence Valley, but results have so far revealed only limited geological evidence of a massive flux of freshwater coincident with the YD initiation (Broecker, 2006a; Rayburn et al., 2011). The freshwater pulse may have followed another route to the ocean, and other research has proposed the Mackenzie Valley (Condron and Winsor, 2012; Murton et al., 2010) as a possible alternative and the
            Fennoscandian Ice Sheet as an alternate source (Muschitiello et al., 2015). Very recent surface exposure ages suggest that the route to the North Atlantic from Lake Agassiz was indeed free of ice before the YD initiation (Leydet et al., 2018), coinciding with evidence of freshening of the Gulf of St Lawrence (Levac et al., 2015), illustrating that meltwater could indeed have followed the St Lawrence Valley route to the North Atlantic.”

            Regardless of its course to the ocean, such a meltwater pulse caused previous cold snaps during the last and prior deglaciations, thus the null hypothesis can’t be rejected in this case. Yet so pressing is the need to publish or perish, that fanciful alternative explanations keep cropping up.

            Shades of Hansen’s PhD thesis on Venus’ atmosphere, which he knew to be wrong when he wrote it. Bad science drives out good, in a shameful version of Gresham’s Law.

        • He gave it. Increased volcanism as ice loads are reduced, a frequently observed phenomenon.

          And Moore’s point is that there was not a corresponding increase in palladium at this site.

          The same pack of advocates for this repeatedly falsified hypothesis, basically just looking easily to publish so as not to perish, have lately glommed onto platinum, since all their previous lame attempts at adducing “evidence” have been so promptly debunked.

          • ” He gave it . Increased volcanism as ice loads are reduced , a frequently observed phenomenon ” ….Javier wrote the exact opposite Tillman : ” Abrupt cooling results in an increase in the ice load over certain parts of the crust leading to an increase in volcanic activity ” .. Both of you are very confused and intellectually dishonest ….Volcanism increased during the Little Ice Age then abated in the modern warming period .

          • In response to DaveR–I did think of that, but an impact at sea has a difficult time explaining large volumes of soot.

      • Clearly this was an article written for the general public, not a paper for a scientific journal. It’s also pretty clear you have an emotional dog in the race. The only way the article could be considered dishonest would be if the author invented, or suppressed findings. Do you have any evidence of that ?

        If theories required “indisputable evidence” to be aired there’s be few theories advanced. After 87 years the existence of “dark matter” hasn’t been proven. And, this year the “Age of the Universe’s” birthday took a big time torpedo.

        • A possible 12.6 v. 13.8 billion years is hardly a torpedo. Barely a BB.

          Between Newton’s and Einstein’s concepts of gravitation, over two centuries passed. Dark energy and matter have lots of time yet to be confirmed, found false or refined.

          • Reduction by an order of magnitude to 1.3 billion years would be a 16″ AP projectile hit which missed the magazine. A torpedo hit sinking the ship would be a further power of ten down to just 130 million years.

      • All science is “hypothesis driven”! You develop a hypothesis and then seek to prove or disprove it. That’s how the system works.

        • Prove or disprove are the wrong words for the scientific method. Math does proof. Science either confirms a prediction made on the basis on an hypothesis, or shows it false.

      • Javier, you need a reading list: https://cosmictusk.com/younger-dryas-impact-hypothesis-bibliography-and-paper-archive/ There is substantial — indeed overwhelming — evidence for the YDIH presented in more than 100 papers, many from workers independent of the original publishing team. I also recommend this book from a former skeptic: https://cosmictusk.com/james-powell-younger-dryas-comet-book/ Even PROFESSIONAL skeptics are coming around: https://cosmictusk.com/marc-defant-rogan-hancock-younger-dryas-impact/

    • “This is how actual science is done.”

      But it was all done by white people. So. RAYSIS!

    • This is not science, but more circular reasoning. The scientific method indeed requires an hypothesis upon which to make testable predictions, but that’s not what the acolytes of this blind faith belief do.

      Were there a crater, then cultic adherents of this baseless assertion could hypothesize that the impact which created it caused some of the extinctions around this time and even the YD climatic downturn. But there is no crater, for the simple reason that there was no impact.

      Advocates of this pure speculation claim that the impactor hit the Laurentide Ice Sheet but didn’t penetrate it, hence no crater. Such an event could not have had the consequences they posit.

      Compare and contrast with how the Alvarezes operated in the case of the end Cretaceous extinctions. First, the younger Alvarez found evidence of an impact at the Cretaceous-Paleogene boundary. Then together with others they proposed a testable hypothesis that an impact wiped out the non-avian dinosaurs and many other groups. They found more evidence of an impact, all of which stood up under rigorous questioning. Others looked for an impact site, and discovered in the Yucatan. Impact debris pattern confirmed this as the location. Effects of the cosmic collision explain the disappearance of so many life forms.

      The YDIH gang have nothing of the sort. They have no crater, no valid, indisputable impact debris, nothing but a platinum excursion in random spots, easily explained by normal terrestrial processes.

      Nor does the pattern of extinctions match the “hypothesis”, if the unsupported conjecture may be so dignified. Quite the contrary. Megafauna in the Caribbean should have been wiped out by an impact on North America if their kin in South America were. But in fact big beasts there only died out when humans arrived on their islands, same as happened on the two continents.

      All available genuine evidence shows the ill-founded (at best) WAG false.

      • John, you state “The YDIH gang have . . . nothing but a platinum excursion in random spots, easily explained by normal terrestrial processes.”

        So please provide me and the rest of the trying-to-stay-objective WUWT comment posters & readers YOUR specific, easy, normal-terrestrial-process-based explanation for the enrichment of platinum and the anomalous increase in the Pt:Pd ratio that scientists found in a mud core segment extracted from White Pond, South Carolina, with associated dating to between 12,835 and 12,735 years ago.

        And please don’t point us to references of how volcanoes or basalt flows might be able to concentrate platinum unless you can substantiate that such natural processes occurred in near or near South Carolina within the last 13,000 years.

        • I’ve already cited the eruptions responsible for slightly enhanced Pt on either side of YD onset.

          The volcanoes don’t concentrate the Pt. They simple release it, and it travels on dust around the world.

          • John, in your July 28, 2020 at 12:11 pm, you stated “. . . nothing but a platinum excursion in random spots . . .” But now you claim (presumably because there have been no volcanoes anywhere near North Carolina, USA, within the last 13,000 years) that volcano emissions of Pt travel, and I quote your directly, “on dust around the world.”

            In turn, this causes me to ask you to explain why such widely dispersed dust would then selectively deposit in a few “random spots” around the world, such as White Pond.

            I was hoping for the “easy, terrestrial process explanation” that was previously asserted to exist. Perhaps there is no such thing?

    • This is more of the same garbage. Here is what the incontrovertible science show caused the YD:

      Geologists, paleoclimatologists, oceanographers and atmospheric scientists have a very good grasp of what caused the YD and the alternating stadials and interstadials during glaciations and deglaciations (terminations). Cold, fresh water released into the oceans by armadas of icebergs (Heinrich events) or by meltwater from the ice sheets.

      The YDIH and other gods on machines “explanations” are not only wrong, having been repeatedly shown false in detail, but totally unnecessary. They’re time-wasting exercises akin to looking for evidence of phlogiston after the isolation of oxygen or for the humors theory of disease after the discovery of germs.

      The only problem with the meltwater hypothesis before 2005 was ascertaining by which route the flood entered the ocean. It had been shown by 1989 that the usual drainage of the Laurentide Ice Sheet (LIS) via the Mississippi didn’t flow during the YD. Broecker (please forgive him for being the “Father of Global Warming”) in that year suggested the St. Lawrence, which seemed a natural given Niagara’s date of c. 12,000 BP. But analysis of its channels and sediments didn’t really show any clear sign of such an ice-dammed outwash flood. And in any case, proglacial meltwater Lake Agassiz was SW of the LIS. An arm of it could have hooked around the southern face of the retreating LIS, but the lay of the land was against this possibility.

      And there the situation stood until 2005, when Tarasov and Peltier proposed that the meltwater discharge was not into the Gulf of Mexico or North Atlantic, but into the Arctic Ocean, via the MacKenzie River drainage.

      https://www.atmosp.physics.utoronto.ca/~peltier/pubs_recent/Lev%20Tarasov%20and%20W.R.%20Peltier,%20Arctic%20Freshwater%20Forcing%20of%20the%20Younger-Dryas%20Cold%20Reversal,%20Nature,%20435,%20662-665,%202005.pdf

      The last deglaciation was abruptly interrupted by a millennialscale reversal to glacial conditions, the Younger Dryas cold event. This cold interval has been connected to a decrease in the rate of North Atlantic Deep Water formation and to a resulting weakening of the meridional overturning circulation owing to surface water freshening. In contrast, an earlier input of fresh water (meltwater pulse 1a), whose origin is disputed, apparently did not lead to a reduction of the meridional overturning circulation. Here we analyse an ensemble of simulations of the drainage chronology of the North American ice sheet in order to identify
      the geographical release points of freshwater forcing during deglaciation. According to the simulations with our calibrated glacial systems model, the North American ice sheet contributed about half the fresh water of meltwater pulse 1a. During the onset of the Younger Dryas, we find that the largest combined meltwater/iceberg discharge was directed into the Arctic Ocean. Given that the only drainage outlet from the Arctic Ocean was via the Fram Strait into the Greenland–Iceland–Norwegian seas, where North Atlantic Deep Water is formed today, we hypothesize that it was this Arctic freshwater flux that triggered the Younger Dryas
      cold reversal.

      Perhaps their paper didn’t get the respect it deserved because the North Atlantic paradigm ruled so strongly. The chain of lakes from Manitoba across the NW Territories, marking the retreating LIS edge stared everyone in the face, but like geographers since AD 1500 looking at South America and Africa before Wegener, had eyes but couldn’t see.

      In any case, two years later Firestone and unindicted coauthors perpetrated their ET impact hypothesis, if the wild conjecture may be so designated. It was promptly shown false, and has been repeatedly since then, but its easy career-making potential meant that it took on a zombie-like existence, with a voodooist cult following. It lurches along, from one new lame excuse to another.

      Even loopier “hypotheses” have been floated, in this debased age when just about anything but reality gets published readily. Broecker’s former coauthor Kennett even deserted to the Dark Side of the farce.

      But a few real scientists over the years have investigated the MacKenzie River hypothesis, and repeatedly confirmed it. Both observations and simulations of drainage and the effect on the Atlantic meridional overturning circulation (AMOC, the zonally-integrated component of Atlantic surface and deep currents). and atmospheric circulation supported it.

      After this 2018 paper, the case is effectively closed, as it long ago should have been, had the scientific method ruled. Science is never settled, of course, but no present alternative hypothesis can compete with this ice-rafted deluge of valid evidence. The iceebergs and meltwater deliver cold, fresh water to where it will have the most effect, and the flow lasts hundreds of years, solving the issues of duration and amplitude of YD cooling.

      https://www.nature.com/articles/s41561-018-0169-6?proof=trueMay.

      A period of cooling about 13,000 years ago interrupted about 2,000 years of deglacial warming. Known as the Younger Dryas (YD), the event is thought to have resulted from a slowdown of the Atlantic meridional overturning circulation in response to a sudden flood of Laurentide Ice Sheet meltwater that reached the Nordic Seas. Oxygen isotope evidence for a local source of meltwater to the open western North Atlantic from the Gulf of St Lawrence has been lacking. Here we report that the eastern Beaufort Sea contains the long-sought signal of 18O-depleted water. Beginning at ~12.94 ± 0.15 thousand years ago, oxygen isotopes in the planktonic foraminifera from two sediment cores as well as sediment and seismic data indicate a flood of meltwater, ice and sediment to the Arctic via the Mackenzie River that lasted about 700 years. The minimum in the oxygen isotope ratios lasted ~130 years. We suggest that the floodwater travelled north along the Canadian Archipelago and then through the Fram Strait to the Nordic Seas, where freshening and freezing near sites of deep-water formation would have suppressed convection and caused the YD cooling by reducing the meridional overturning.

      The scientific method still survives in a few refugia.

      Comparing the last termination with the previous six going back to the Mid-Pleistocene Transition (the switch from ~40,000-year glacial cycles to those averaging ~100,000 years) is instructive, but beyond the scope of a comment. The four before Termination VII occurred during the transition, ie ~700 Ka to 1.2 Ma. Suffice it to say, that stadials (coolings) caused by meltwater and iceberg armadas are evident in all of them, although not all have coolings as pronounced and long-lasting as the YD. Those that do reflect similar Milankovitch cycle alignments, hence summer solar insolation regimes. Those which don’t experienced higher insolation.

  2. Now, do the same thing in a few hundred other sites and get similar results and we have a plausible theory. Science, not BS.

  3. The UCSB newspaper had an article about intensely baked earth from sites in the Middle East from that time. The hypothesis of the UCSB researchers was that the comet or asteroid had fragmented before striking the earth, which accounts for the widespread fires and debris.

    • Physics shows such a cometary encounter impossible. It would have to be a millions times more massive than the Tunguska blast, but the chemical signature of such an improbable airburst is totally lacking.

  4. The study was intensive and meticulous on a few cores from one lake/pond. The carefully worded report provides suggestive but not overwhelming evidence of comet or other extra terrestrial impact causing the Younger Dryas sudden cooling. Contrary or other hypotheses are presented fairly.

    I like this kind of science. Real data from empirical evidence analyzed with great technical expertise. The findings are compelling but not blown out of proportion. More of such studies should be performed.

    • Yes, sadly it is rare to find this kind of well-balanced, objective attitude in any earth science these days.

      It is strange the two most clearly visible changes in the sediment record around that time go without comment. There was a very abrupt and marked change in colour at -230cm which apparently is about 13,500 BP. The second is about 100y after the Pt anomaly.

      Again, a very clear and abrupt change. When trying to find evidence of a clear and abrupt change due the hypothesised impact, it seems odd to completely ignore these adjacent events in the core.

    • Part of a naturally occurring deglaciation, ie termination. Same as in all previous ice sheet terminations. No special, ET explanation required.

      • The arguments sound convincing to me—particularly that this is one of many similar events where no evidence was found for an ET cause in the prior examples. And of course not least because mosh agrees with the YDI hypothesis signaling that it must be wrong 🙂

        So I’m wondering what part of this controversy explains the emotional content in both camps?

        Is it that the suddenness of the YD event in the midst of a glacial termination calls into question the dogma of the CO2 master control knob? Is it imagined that YDI would rescue the dogma from inconvenient evidence?

        Why are the authors so invested in a supposedly long-debunked hypothesis? Obviously only the authors know their true motivations but what is a reasonable explanation?

        And apart from that, how do the CO2 worshippers explain YD if not resorting to an impact theory? Are we supposed to believe that there was a huge sudden drop in CO2 followed by a huge sudden spike inside of a few centuries?

        • YDIH cult members fall on boths sides of the CACA hysteria, but among academics, most are alarmists. They may be invested in the cockamamie scheme because it overrides natural cycles with yet another god on a machine external “forcing”

          My impression is however than most the YDIH Team are in to garner easy publications. I don’t advocate journals censoring their “work”, but, like CACA “papers”, YDIH drivel is a lot easier to gin up than real, reproducible scientific research.

          I suspect that many of the gang know their “work” is a load of caca, same as for the CACA Team. But it makes their lives simpler and richer, through grants and low effort publishing.

  5. This seems like another theory about rapid climate change and widespread extinction, the iridium anomaly.

    Iridium is a very rare element in the Earth’s crust, but is found in anomalously high concentrations (around 100 times greater than normal) in a thin worldwide layer of clay marking the boundary between the Cretaceous and Paleogene periods, 66 million years ago. This boundary is marked by a major extinction event, including that of the dinosaurs along with about 70% of all other species. The clay layer also contains small grains of shocked quartz and, in some places, small weathered glass beads thought to be tektites.

    The question that occurs to me is whether a meteor/meteorite could cause widespread burning. We have the Tunguska event where an apparent meteor explosion knocked over hundreds of square miles of trees but, notably, did not cause widespread burning.

    Forest fires are a common event and sediments don’t provide sufficient resolution that you can tell that forest fires all over the continent occurred close enough to the same time that you could blame them on something extraterrestrial. Widespread drought can also cause forest fires. link In other words, climate change could have caused all the soot particles observed by Moore et al. and others, not vice versa.

  6. What is maybe even more interesting is the reason for the very rapid warming at the end of the Younger Dryas period. Several degrees in just a few decades.

    • Hear hear. For me, the interesting point is not the beginning, but the end. We would expect whatever caused the cooling to gradually taper off over the years. Instead, after about 1300 years, the temperature suddenly jumps up again to about the trend line. Odd!

      • Disputin:

        Exactly as happens with regard to volcanic eruptions today.

        Initial cooling from their SO2 emissions, then subsequent warming back to pre-eruption levels, or a bit higher, after their SO2 aerosols have settled out of the atmosphere.

    • Agreed. It is like the CO2 cult. It gives me no shortage of fun seeing the CO2 skeptics being YDI believers. They use the same type of arguments they so strongly criticize. It so explains the wars of religion.

    • I guess almost any belief can generate cult like behavior, but on the spectrum, some just develop strong opinions and on the other there are varying degrees of contrarians. In any case, speculation and discussion of mysteries is fun basically.

    • With impact proxies found throughout North America, into South America, Europe and now Syria?

        • John Tillman , ” the YDIH gang ” .A gang ? ” They have nothing …..no crater , no valid indisputable impact debris ,nothing but a platinum excursion in random spots ,easily explained by random terrestrial processes “. That’s not true .There are enhanced nickel , osmium platinum and iridium concentrations in the Younger Dryas Boundary layers ..The author of this study explicitly mentioned this in the article : ” In the last few years scientists have found a variety of exotic impact related materials in the [ YDB ] layers all over the globe . These include high temperature iron and silica rich tiny magnetic spheres, high temperature melt glass and elevated concentrations of nickel osmium iridium and platinum ” . Both you and “guest gaslighter” Javier [ funnily enough Javier stubbornly refuses to admit he foolishly contradicted himself on ” hypothesis driven science ” .This has not captured your attention either or compelled you to chide him if you did notice .So much for your rational skepticism. Mr Tillman . ] testified on this thread that iridium is a definitive extraterrestrial signature…The amplified iridium exists contiguous with platinum deposits yet you ignore this item of evidence for the Younger Dryas Impact Hypothesis . Both of you have contradicted your arguments. This is what you wrote Mr Tillman : ” Ir. is a much better space origin marker than Pt. ” ..Actually platinum , nickel , iridium and melt-glass combined are the consummate package of cosmic impact marker evidence. Moreover, I am still waiting for the copious evidence of massive volcanic tephra and sulphate residue in the Younger Dryas Boundary layers coinciding with the platinum to validate your alternative hypothesis that Javier contends is bad ” hypothesis driven science despite supporting this method himself…The Phys .org link you cited discusses Late Holocene volcanoes and platinum excursions..The Younger Dryas was Late Pleistocene and the author of this article Charles Rotter is adamant that the ” Younger Dryas Boundary sites with elevated platinum do not have other markers of large scale volcanism ” Will you persist in avoiding the cognitive dissonance and hypocrisy criticism s Javier ? .

          • VEI6 eruption in Germany, c. 12.9 Ka:

            40Ar/(39Ar) ages of sanidine phenocrysts from Laacher See Tephra (12,900 yr BP): Chronostratigraphic and petrological significance

            https://ui.adsabs.harvard.edu/abs/1995E%26PSL.133..163V/abstract

            https://ui.adsabs.harvard.edu/abs/2008PPP…270..196D/abstract

            https://ui.adsabs.harvard.edu/abs/2002QuRes..58..273B/abstract

            “Within a period of a few weeks toward the end of the Allerød Interstadial, the major Plinian eruption of the Laacher See volcano produced some 20 km 3 of eruptiva, covering and preserving the late-glacial landscape in the German Central Rhineland over an area of more than 1000 km 2. Correlation of terrestrial archives with the Greenland ice-core records and improved calibration of the radiocarbon timescale permit a precise, accurate age determination of the Laacher See event some 200 yr before the onset of the Younger Dryas cold episode. Carbonized trees and botanical macrofossils preserved by Laacher See Tephra permit detailed regional paleoenvironmental reconstruction and show that open woodland were typical for the cool and humid hemiboreal climatic conditions during the late Allerød. This woodland provided the habitat for a large variety of animal species, documented at both paleontological and Final Paleolithic archeological sites preserved below Laacher See deposits. Of special interest are numerous animal tracks intercalated in Middle Laacher See deposits at the south of the Neuwied Basin. This knowledge may help to evaluate possible supraregional impacts of this volcanic event on northern hemispheric environment and climate during the late Allerød.”

            Other citations available in English and German, but am stopping at three so as not to be moderated.

            https://en.wikipedia.org/wiki/Eifel_hotspot

          • Thoroughly debunked in detail, repeatedly: “high temperature iron and silica rich tiny magnetic spheres, high temperature melt glass”.

          • By “gang” I mean the same individuals milking this myth over and over again, in order to publish so as not to perish. No matter how many times their phony “evidence” be shown false, the clique keeps coming back, with their cult of faithful followers.

        • Hey John Tillman, that’s really authoritative sounding. Except Pete Schultz of NASA, and Ted Bunch retired NASA, are co-authors of the YDIH and have confirmed the proxies as entirely in line with the KT boundary science, which is the standard. Oh, and Andronikov, of Arizona’s Lunar and Planetary lab, confirmed them independently, as have many others. Certainly you have failed to read LeCompte 2012: https://www.pnas.org/content/109/44/E2960.abstract
          Read it very carefully now, so you won’t embarrass yourself in the future making baseless declaratory statements on the internet. https://cosmictusk.com/younger-dryas-impact-hypothesis-bibliography-and-paper-archive/

          • The Greenland Pt result doesn’t support a catastrophic impact, since it’s not consistent with meteoritic minerals, as summarized in Green’s PhD thesis, whose advisers included two Durham U experts on the Eifel Hot Spot:

            http://etheses.dur.ac.uk/13490/1/C_Green_thesis_final_CORRECTIONS.pdf

            “An alternative explanation for the Pt spike is that it is derived from a large
            iron meteorite impact, as suggested by Petaev et al. (2013). Recent research on the
            YDIH links the Pt spike to the YD (e.g. Wolbach et al., 2018a, b), however, there are
            chronological discrepancies between YDB sites (the mean age of the YDB layer is
            12.938± 0.25 BP; Firestone et al., 2007) and the GISP2 Pt spike. A large bolide
            impact could generate significant amounts of dust and an aerosol akin to explosive
            volcanic eruptions (Toon et al., 1997; Firestone et al., 2007). Similar to volcanogenic
            87
            aerosol from the LSE, atmospheric processing and post-depositional processes do
            not provide an explanation for a ~30-100-year offset between YDB sediments and
            the GISP2 Pt spike. Therefore, it is highly unlikely the hypothesised YDIH impactor
            is the origin of elevated Pt concentrations at the GISP2 Pt spike. Alternatively, if the
            GISP2 Pt spike is considered the result of another impact with more localised
            effects, a noncataclysmic impact, such as the Cape York meteorite impact, could
            deposit Pt onto the Greenland Ice Sheet (Boslough, 2013).”

          • As you must know from CACA “literature”, it’s easy in these times of debased “science” to get pure dreck published, so please instead of mentioning links, summarize their content.

            Thanks!

  7. So we have the ‘Dam Breach’ hypothesis for cooling via disrupted ocean currents, and also the ‘Impact’ hypothesis, causing cooling by soot generation.

    What would we call it if the impacting bolide actually hit the dam?

  8. THE GLOBAL FLOOD OF NOAH’S DAY
    The Flood of Noah’s day (c. 2348 BC) was a yearlong global catastrophe that destroyed the pre-Flood world, reshaped the continents, buried billions of creatures, and laid down rock layers all over the earth. As God’s judgment on man’s wickedness, only eight righteous people were spared aboard the Ark, plus representatives of every kind of land animal.
    Dig Deeper
    A Global Flood—Rising Above All Doubt
    Worldwide Flood, Worldwide Evidence
    Was There Really a Noah’s Ark & Flood?
    https://answersingenesis.org/search/?refinement=&language=en&q=flood

    • 1) Zero evidence of a global flood equal to 3.5 times all the ocean water on Earth at any time in geologic history, and all the evidence in the world against this myth.

      2) The YD was about 10,000 years before the putative date of Noah’s Flood.

      Answers in Genesis are blasphemous liars, preying on the gullible and ill-informed.

      • 3) On the order of a billion land animal species have existed. With seven each of the clean and two each of the unclean, please explain how you get them all on the Ark. How does a small human family care for them for a year. And how they all get to the Ark in the first place.

        4) Where did the water come from, and where did it go?

        5) Why do marine and terrestrial rock layers intersperse? Why do fossils sort by geologic age rather than size or shape, if all deposited at the same time?

        6) Why do real geologists not use “Flood geology” to find mineral and hydrocarbon deposits?

        Thanks!

        • As amazing as it might seem the scientific consensus from the mid 18th to the early 19th centuries was that the Biblical Flood was responsible for the transport of the huge erratic rock blocks found many kilometers away from their place of origin (the first evidence of glaciations). It defied common sense that those huge rocks could be transported by water, but one didn’t argue with the Bible those days, the same as one doesn’t argue with the IPCC reports now. It was/is detrimental to one’s career.

          • Agassiz was a brave scientist, who followed where the evidence led, guided by the Work of God, rather than His presumed Word.

            He was able to persuade the Rev. Buckland on their tour of Scotland, but the good Reverend buckled under pressure from his biblically blinded colleagues.

            On ice ages, Agassiz was right. Not so much on evolution, creationism and racism. On human diversity, Darwin was right and Agassiz wrong, but today creationists try to tar the liberal Darwin with charges of racism.

        • John Tillman the problem with the Laacher See eruption hypothesis approximate to the onset of the Younger Dryas is that it was a magnitude 6 scale volcano analogous to Mt Pinatubo 1991 and although it may have ejected more cooling sulphate [ 83mt ] into the atmosphere than the more powerful Tambora caldera of 1815 [ estimated 70 mt ] , the climatic effects of both Pinatubo and Tambora only lasted several years to a decade …Now applying deductive reasoning why should the LSE have triggered centuries of resurgent glaciation but not Tambora and Pinatubo ?. Something else must have caused the cataclysmic phenomena observed and the most plausible hypothesis for which there is compelling evidence is a comet debris bombardment episode …
          Volcanic activity cannot account for the YDB cobalt nickel iridium and chromium peaks coinciding with melt-glass you pretend are ” phony” ..They are real and evidence of impacts You remarked that iridium was a distinctive meteoritic signature and there it is .
          Researchers working in Syria also discovered unique impact tracers . See ” Evidence of Cosmic Impact at Abu Hureya, Syria at the Younger Dryas Onset [ 12.8 ka ] : High Temperature Melting at 2200 C ” : ” This carbon infused melt-glass is associated with melted magnetic spherules and nanodiamonds along with abundance peaks in nickel , cobalt ,iridium and platinum …..The only known natural dynamic events that produce Fe silicides are cosmic impacts , lightning strikes and nuclear detonations ……A suite of elements , including platinum ,iridium , nickel cobalt and/or chromium in variable abundances ,has been previously reported in spherules meltglass and sediment at 30 other YDB sites across three continents including Greenland . The results from Abu Hureyra closely match these other studies which attribute those enrichments to a cosmic impact event ….The observed range of characteristics for AH glass ….allow us to exclude all potential origins for AH glass except cosmic impact melted glass and tektites ….The collective evidence is best explained by the [ cosmic impact ] hypothesis ”
          ” No impact proxies have been found anywhere ” you said John ?

          nature.com/articles/s41598-020-60867-w

          • More from the same team.

            Again, of course Pt has been found in a lot of places, because there were at least two big eruptions before and after YD onset. The Syrian results show the downwind effect of the Eifel Hotspot eruption.

            Slightly elevated Pt doesn’t even confirm an impact, let alone any influence on climate or extinctions.

            The supposed glass and tektites aren’t from an impact, either.

          • PS: I’m not arguing for the Laacher See eruption (LES) hypothesis as an explanation for the YD. That cold snap is well and fully explained by the meltwater pulse hypothesis, which by now is really more of an observation than an hypothesis.

            I mentioned the Eifel Hot Spot as a possible terrestrial source for elevated Pt. However, I’ve just found Green’s thesis from last year, in which someone (she) finally analyzed the chemical makeup of LES tephra. In it, she finds that the elemental mix signature of the Greenland Pt layer matches neither LES ejecta nor any known meteorite class.

            Thus, neither of those proposed alternatives to objective YD reality is supported.

        • John Tillman you lied [ ” No impact proxies have been found anywhere ” ] and contradicted your own argument so you are in no position to ridicule anyone else ….Javier made an absolute fool of himself and would do well to understand that cognitive dissonance and doublethink are traits of cult fanatics …As for ancient flood traditions there are hundreds of them across the worlds cultures and civilizations including Mesopotamia , and many are embellished folk memories of natural disasters attributed to the wrath of supernatural deities. Some have theorized that the post YD Glacial Meltwater Pulse rapid rise in ocean levels inspired the flood myths [ Stephen Oppenheimer explores this in his book Eden in the East : the Drowned Continent of Southeast Asia ] or the neolithic Black Sea catastrophe regarding the Old Testament [ That is taught at universities ] ..They are not literally authentic in every detail. Are you prepared to mock any other religions or indigenous cultures that have flood folklore Mr Tillman ?…Surely you are not that Woke

          • No lie. I cited the many studies showing “evidence” for an impact not to exist.

            Of course many cultures have flood myths, since floods are common.

            But the biblical flood myth cannot possibly be related to the YD outwash, which, as noted, occurred around 9000 years before the supposed time of Noah.

            But if you imagine that a global flood occurred c. 4400 years ago, covering the highest mountains, please start by saying whence came more than 3.5 times as much water as in all oceans, and where it went. Then please state how a human family could find space for and care for on the order of a billion species on their boat.

            Thanks!

  9. Comets and meteorites are business as usual things.
    Most of us will remember the 1994 impact of comet Shoemacher-Levy 9 on Jupiter. In 2016 amateurs captured a smaller event with their telescopes. Nowadays it looks like Jupiter is hit every year by several bigger celestial objects. In Antarctica there are places littered with meteorites, researched by ANSMET. As a hobby I used to listen to meteor showers with a ham radio (meteors ionize upper atmosphere molecules which then reflect far away radio stations making this otherwise non receivable stations audible for some seconds). Many times I was impressed (if not feared) by the enormous amount of space dust that hits us every minute -also outside the shower peaks- that I heard live coming from the speaker.
    So, to summarize, it is not uncommon to find signs of them in any geological sample, it is what you would expect. Thus YDIH needs much more confirmation then just finding common space dust.

    • Max, do you have any recordings of those meteor showers from your ham radio you could send me?
      I think I would use these sound files to overwrite my grandson’s rap “music” on his ipod.
      Anything has to easier on the ears than rap 🙁

    • Max,

      The impact proxies are not match by the global daily “rain” of cosmic dust …

  10. I suggest a careful reading of Plato’s “Timaeus”, especially the passage referring to Atlantis. Note the date of the event. Then look for bibliography on nanodiamonds and you will find that the geological horizon that contains them is that of the Younger Dryas. Return to Plato for the evolution of man (linear or circular). I think, like me, you might be wondering if Younger Dryas was a Nuclear Winter from a Nuclear War.

  11. As I have pointed out many times in WUWT, this is really bad science. There may well be evidence of a cosmic impact, but that doesn’t prove it caused the Younger Dryas. The YD is one of many abrupt climate reversals that occurred in the late Pleistocene. A cosmic impact is a single event that can affect climate for only a very few years. But the YD cooling lasted for more than a thousand years! To maintain a cold climate for that long from impacts would require something like 500 impacts! And there were other abrupt climate changes before and after the YD.

    What IS consistent about the YD, the other D/O abrupt climate changes, and in fact every climate change over the past 800,000 years is that EVERY abrupt climate change exactly matches 10Be production rates in the atmosphere which means a low level of the sun’s magnetic field.

    I have no quarrel with this paper’s evidence of an impact, but to claim it caused >1,000 year cold climate is total nonsense!

    • Don Esterbrook:

      1. 10Be levels decrease when there are interfering layers of volcanic SO2 aerosols circulating in the atmosphere. This is provable.

      2. The 600 year LIA was due to extensive volcanism. All that a > 1000 year cold climate would require is a more of the same.

      • The LIA wasn’t caused by volcanism. There were more big eruptions before and after the LIA than during it.

        What did cause it were solar minima, eg the Spörer (1460-1550), Maunder (1645-1715) and Dalton (1790-1830) Minima, plus possibly the Wolf Minimum (1280-1350).

        • John Tillman:

          If there were solar minima, then one would expect a constant period of low temperatures due to a weak sun. However, short periods of higher temperatures are interspersed through the LIA temperature record. How could that happen?

          The cause is obvious when one examines the Central England Instrumental temperature record, which began in 1659. It shows that all temperature excursions below 0.0 deg. C coincide with increased SO2 aerosols from a volcanic eruption (and warmer times are periods when there are no eruptions). Thus LIA cooling due to a weak sun is complete FICTION
          https://www.osf.io/b2vxp/

          • Cyclical countertrends owe to oceanic curculation and to periods of higher solar activty within and between the generally low minima. Indeed, these solar variations correspond well. The longest, most pronounced warm cycle within the LIA occurred in early in the 18th century, coming out of the depths of the Maunder Minimum. That warm interval was greater in length and amplitude than the late 20th century warming.

            OTOH, volcanoes can’t account for a centuries long climate fluctuation, especially when the warmer periods before and after it had more big eruptions.

          • Maunder ended long before the puny VEI4 you cite, and the warming lasted until long after the other puny VEI4 you mention.

            Your lame hypothesis is totally busted.

          • John Tillman.

            You TOTALLY missed my point.

            Temperatures ALWAYS rise when there is a period of no volcanic eruptions, as happened during the early 18th century warm period.

            It has no relation to the size of the eruptions before or after, or when when it happened.

            And it is not a theory, just an easily provable fact;.

          • Burl,

            You somehow missed the fact that there volcanic eruptions in the 18th century, the most famous of which was Laki, 1783-85. Mt. Asama erupted in 1783 as well; Mt. Merapi, Java, 1786, and Kilauea in 1790. In 1792, the collapse of one of Mt. Unzen’s several lava domes triggered a megatsunami, which killed 14,524 people in Japan’s worst volcanic-related disaster.

            But during the warmer first half of the century, such as Trevejo, Canaries in 1706, Mt. Fuji, 1707-08; the powerful Mt. Awu, North Sulawesi eruption of 1711; Cotopaxi, 1738, and Makian, North Maluku, 1760.

            Throughout the century, Vesuvius erupted relatively severely in 1707, 1737, 1760, 1767, 1779 and 1794.

          • John Tillman:

            Your post of July 31, 5:06 pm

            First, I did not attempt to label every downward excursion on the graph. those that were labeled were sufficient to prove my point.

            However, I did compare my graph to those listed in your message:

            The 1783 eruption of Laki (Grimsvotn) is shown, but I did miss the VEI4 eruption of Asama in the same year.
            Mount Merapi did not appear on the graph because it was only a VEI1 eruption, according to my reference.
            Kilauea in 1790 is shown.
            Mt. Unzen, in 1792, is listed as a VE2 eruption, and barely shows on the graph, and was not identified
            Trevejo, in 1706 is not listed in my reference. Also barely shows, and was not identified.
            Mt. Fuji, 1707-1708 is identified on the graph as a 1708 eruption (it erupted on Dec. 16, 1707)
            Mt. Awu, 1711, is not in my reference. and there is no sign of it on the graph.
            Cotopaxi, 1738, is identified as a VEI2 eruption, It shows, but was one not identified.
            Makian, 1760, was identified
            The Vesuvius eruptions were all small VEI3, or VEI3? eruptions, and although they appear on the graph, their excursions were too small to have been identified.

            The real point of all of this is that all temperature changes shown on the CET data set were of short duration and their dates all correlate with a volcanic eruption. There is zero evidence that low sunspot activity during that period had any effect upon the temperatures.

        • John Tillman:

          Still awaiting a response from you regarding my July 29 post. This is a very important issue, which needs to be addressed.

          • It’s right above your last comment.

            I’d have thought it obvious that in between the long minima there would be cycles counter to the secular trend.

          • John Tillman:

            Sorry, I thought you were responding to someone else’s post. My bad.

            The long warm period in the early 18th century corresponded to the 120 month interval between the Aug. 8, 1727 VEI4 eruption of Orafejokull, and the Aug 27, 1737 VEI4 eruption of Fuego. There were no other VEI4 eruptions within that interval, and, as always happens, in intervals when there hasn’t been a VEI4 eruption for 3-4 years, temperatures always rise (higher for longer intervals).

            The warm period was definitely NOT due to your convoluted explanation.

          • Not the least bit convoluted. Couldn’t be more simple.

            The Maunder sunspot drought ended. World warmed up until next solar dimming.

            Even the largest eruptions can affect weather for no more than a year or two.

            The fiction is all yours.

          • Burl Henry the Central England Temperature Instrumentation dataset is only one record – not a composition . Remember the Little Ice Age commenced around 1300 – 1350

          • Stuart Hamish says :
            “Remember the Little Ice Age commenced around 1300 – 1350”

            Just off the top of my head I’d look to into the 1300 AD side of that range. Again historian, not scientist. But, there were ten famines, either regional or general in Europe in exactly that time period before the Black Plague hit in 1348. One in particular called The Great Famine (1315-1317) is estimated to have killed seven and a half million people.

          • Stuart Hamish:

            I agree, but the CET data set covers about 300 years of the LIA, including most of the Maunder Minimum and the Dalton Minimum.

            The proven volcanic cause (rather than the hypothesized weaker sun) of the temperature decreases during the the latter 300 year period would undoubtedly have been the same as those of the earlier period.

        • The Little Ice Age was caused and prolonged by a convergence of volcanic activity , solar minima and increased cosmic dust influx … There were more large scale volcanic eruptions during and immediately preceding [ Samalas 1257 ] the LIA than afterward…

          • Stuart Hamish:

            You state “The Little Ice Age was caused and prolonged by a convergence of volcanic activity, solar minima, and cosmic dust influx”

            As I have repeatedly mentioned on this thread, the cause of the LIA was ENTIRELY due to volcanic activity.

            Examination of the Central England Instrumental Temperatures data set completely excludes any evidence of a solar minima, or cosmic dust, effect upon temperatures. Temperature decreases only occur after a volcanic eruption. https://www.Osf.io.b2vxp/

      • IOW, cause of the LIA was the same as for all previous cool cycles of the Holocene, and those of previous interglacials.

      • No ,the 1300 – 1850 AD Little Ice Age was not solely caused by extensive volcanism .
        Read ” The peatland /ice age hypothesis revised ,adding a possible glacial pulse trigger ” , Franzen ,Lars G , Cropp ,Roger A , Griffith Research Online , pp 24 -26

        “The high peaks of cosmic influx to the ombotrophic peatlands correlate surprisingly well with Holocene cold spells ….The latest cosmic pulse [ H12 ] centered over the peak of the Little Ice Age “

        • Stuart Hamish:

          “”No, the 1300-1850 AD Little Ice Age was not solely caused by extensive volcanism”

          And, “The latest cosmic pulse centered over the peak of the Little Ice Age”

          It is IMPOSSIBLE to use ANY proxies to infer temperatures or cosmic radiation when there are interfering
          SO2 aerosols from volcanic eruptions in the atmosphere. They attenuate incoming radiation and give the false impression that the sun has weakened, or that incoming cosmic radiation has changed.

          The proxies are only useful to identify periods where extensive volvcanism has occurred.

  12. How about the idea that our sun has periodic micro nova! This is Ben Davidson’s hypothesis at Suspicious Observers. I find it interesting that such a major climatic event still isn’t well understood.

  13. Well, here we go again…

    I apparently have an advantage here: I actually read the book, “The Cycle of Cosmic Catastrophes” by Firestone, West and Warwick-Smith, printed in 2007. I would observe that a) their research was exhaustive, b) is well documented, and c) was presented in the form of “theory”, with much work left to be done. Notably, they didn’t start out with a hypothesis, and look for evidence to prove it, but rather they found anomalies and then hypothesized possible/probable scenarios that might account for them.

    Volcanism came up far short. They concluded that it was more likely that the fact of increased volcanism at that time was an effect rather than a cause. (Notably, if I recall correctly, it was about this period that the Cascade range became very active with major eruption events.)

    Their theory involves a comet, not an asteroid or meteor, i.e., ice and debris, not a solid rock of iron and nickel.

    And they were able to present evidence that the YDB event may have started 41,000 years ago with super nova in our region of the galaxy, hitting our planet in three waves: a) radiation 41,000 years ago, b) shock wave 34,000 years ago, and c) debris 14,000 years ago. This includes microscopic particles embedded in fossilized bones, particularly tusks…but only on one side, suggesting these creatures were bombarded by extraterrestrial material at extreme rates of speed. They theorize that it may have been either of the two last sequences that ultimately threw the comet into an earth crossing orbit.

    Evidence also includes elevated levels of Helium-3, radioactive potassium (K-40) , carbon glass, etc., etc.

    And even included so called “flood myths” from numerous North American First Nations.

    Fascinating read!

    (For some reason I am reminded of that breed of critics who pan movies without ever having taken the time to actually watch them first. You know?)

    • (Notably, if I recall correctly, it was about this period that the Cascade range became very active with major eruption events.)

      Hmm? Doesn’t seem quite right.
      I don’t have that book, so wonder what was written that now is in your memory.

      Even a super explosion (See: Bruneau-Jarbidge ) would not cause the very long effects of the YD.

      • The book mentions heightened volcanic activity around the YDB, both in N. America and places like New Zealand. Obviously they would have been referring to the Cascade chain. But I recall reading in other sources, unrelated to YDB discussions, this same time frame of activity.

        Again, the authors suggest this activity may be an effect of an impact of such proportions for a variety of reasons, as opposed to be a cause for the layer of various unique elements across a good part of the globe.

        An eruption by a super volcano can be globally catastrophic. There is evidence, via mitochondrial DNA, that the Toba event in Indonesia circa 74,000 years ago may have reduced the population of humans globally to mere thousands.

  14. This is way, way out of my field, although eons ago I got a B.A. in geology. But I have trouble understanding how either a sudden impact or a sudden dam break could cause climate change lasting 1,400 years. Wouldn’t something like that have a short affect for a few years and then return to normal?

    • I think the game changer in this event was the sudden dumping of colossal amounts of ice, out of Hudson Bay, and frigid melt water, primarily through the area of the Hudson Valley, into the Atlantic, in turn thoroughly disrupting the currents of warmer flow from the equator…not to mention similar sudden flows into the Pacific through Washington state, all of which dramatically raised seal levels virtually over night!

      Fireston et al theorize that this event may also have caused the massive collapse of built up sediment banks off the coasts of both N. America and Africa, each a chain reaction to the other, that also would have a very significant effect on the Atlantic currents. Think tsunamis on an almost incomprehensible scale not seen in historic times, literally sloshing back and forth across that ocean.

      Not hard to imagine the effects this scenario would have had on global climate!

      • Such outwash events happen regularly, during glaciations as Heinrich Events, armadas of icebergs, and during deglaciations, as releases of dammed fresh meltwater, with similar effects.

        The YD is just one of many such events during the past glaciation and its termination, like those during and after preceding Pleistocene ice sheets.

    • It takes a long time for SST, salinity and oceanic circulations and oscillations to recover from a continental sized lid of fresh, cold water.

      It takes about a thousand years under present conditions for North Atlantic Deep Water to arise in the North Pacific vía the thermohaline conveyor belt. The quantity of water released during the YD was greater than in the preceding MD and OD, so its duration and effects were more pronounced.

  15. Is the Younger Dryas any different to the termination of Dansgaard-Oeschger events?

    Was the elevated levels of pyrogenic carbon through the whole of the YG due to increased wildfires because of increased aridity?

    Why does the platinum peak occur some 50 years after the soot peak?

    Could volcanic activity be the source of the platinum peak?

    • Yes, volcanism could be, or just random fluctuations from a variety of causes. In any case, the timing is off on the peaks.

      The faithful of the YDIH have nothing. Their tetragrammaton god is false. Maybe because it involves a vowel.

  16. Christoper Moore does excellent work. Unlike most YDB researchers, he isn’t driven by finding a particular result. He coauthored the paper that clearly killed the notion that Carolina Bay type features are impact-related. I think he has presented fairly solid evidence of some sort of impact event(s) at or around the onset of the Younger Dryas. What I have yet to see, is any clear evidence that the impact played a significant role in the onset or coldness of the Younger Dryas. In terms of Late Pleistocene glacial stadials, the Younger Dryas isn’t even particularly anomalous. The real anomaly is the preceding Bølling–Allerød interstadial,

    • The real anomaly is the preceding Bølling–Allerød interstadial

      Not really. The interval between Greenland Interstadial 1 (GI1, Bølling–Allerød) and the Holocene (GI0) is 3000 years. The interval between GI10 and GI8 is 3000 years. The interval between GI8 and GI7 is 3000 years. The interval between GI7 and GI5.2 is 3000 years. The interval between GI19.2 and GI19.1 is 3000 years. The interval between GI17.1 and GI15.2 is… you guessed it, 3000 years.

      If you just align these six 3000-year periods from the Last Glacial Period you get a pattern, not an anomaly. Meteorite impacts can’t have a role in a repeating pattern.

      • Long term Schwabe cycle variability would tend to produce D-O intervals of 863, 1726, and 3453 years.

        • No evidence that solar activity plays a role in D-O events. And a 3000 year repetition could not be explained by a 3450 year periodical cause because it would produce a 450 year shift at each oscillation. In three 3000 years oscillations you are falling behind by 1350 years already. Almost half a period.

          • Javier
            July 28, 2020 at 1:31 pm

            Have you got these intervals illustrated? I’ll need to see rather than taking your word. I’m used to you making a pigs ear of the intervals on your own charts on your Climate Etc posts, remember?
            I may have evidence for solar activity driving D-O events for all you know.

          • Javier, I note that you linked the paper ‘Reduced solar activity as a trigger for the start of the Younger Dryas?”. It was 7 * 1726.5 years before the 1215 AD start of the LIA. There was a grand solar minimum series starting from close to 10870 BC.

          • I have had a close look at the D-O event series, and I can see many instances of compound intervals of multiples of the 1726.6 year GSM cycle, but only one interval at that length. It shows up more often at 1726.6 years as cold events in the noise between the D-O events. It’s part of the picture of D-O warming events but not the whole picture.

      • The peak-trough has a very consistent ~1,500-yr period (3,000-yr for peak-peak or trough-trough).
        The anomaly isn’t in the timing. It’s in the warmth and rather large CO2 spike. I agree on the timing.

        • B/A warmth gain similar to that of prior D/O events, which started from a colder base during the LGM and earlier.

    • IM undeducated O, a slightly larger than usual D/O excursion might be expected during deglaciation, so the B/A isn’t that anomalous a warm spike, compared with those during the LGM and earlier in the last glaciation.

    • Big volcanic eruptions before and after the start of the YD explain any Pt excursions better, IMO.

      And are better timed.

      Such as the VEI6 in the Eifel Hot Spot, c. 12.9 Ka.

      • Of course, there could have been small impacts on the GIS and LIS, boosting regional Pt signature.

  17. “Volcanic eruptions are another possible source of platinum, …” Not just any volcanic eruption. Ultramafic eruptions, which are rare and tend to not be effusive or explosive, might provide an elevated PGE signature, but it probably wouldn’t be widespread.

  18. Just a side note here, Pt is also in the x-ray defraction equipment so don’t be fooled by that.

  19. I wonder why catastrophic explanations have such a strong appeal to people and are so popular. Even if global catastrophes do exist, they are extremely rare so it is a lot safer to bet on the explanation being somewhere else.

    A common theme is that you have to take an event and make it look unique even if it has been happening many times. For that it helps if the event is the most recent one of its kind as then we have more information, and better resolution to make it look unique.

    Cooling periods like the one that took place at the onset of the Younger Dryas are very common. There were probably a couple of dozens in the last 100,000 years. What makes this one special is that it is the most recent one. We have more and better proxies for it. We can claim uniqueness because the deglaciation had already started. We can analyze charcoal evidence for it and say the world was set ablaze without anybody demanding to see what happened during previous cooling periods of the same kind. We can claim a meteorite was responsible without having to explain what was responsible for all the rest of the similar cooling periods. It is a unique event because we have defined it as such so a unique explanation can be made responsible.

    Now you see this is the same tactic used with the present warming period. It is made unique because it is the one we have better information (even satellites) and a much higher spatial and temporal resolution. then we can ignore all other similar warming periods during the Holocene and claim that this one is unique and demands a unique explanation. Then we can claim that CO2 is responsible without having to explain what was responsible for all the rest of the similar warming periods.

    Lyell took Cuvier to the bushes for a serious beating, but the catastrophists refuse to yield. There is only one thing I don’t understand. How is it possible that people that strongly criticize the CO2 catastrophism then go out and subscribe to meteorite catastrophism to explain the YD. It is the same thing folks. I guess it has to do with the strong appeal that catastrophic explanations have to people. Perhaps it comes from not understanding probability properly. Over the entire geological record global catastrophes have indeed taken place, but when looking at a particular recent event the chances are abysmally low. Same principle as the lottery tickets. Somebody is going to win, but your chances are awful.

    • IMO the last cold snap owing to the same cause as the YD was the 8.2 Ka Event:

      https://en.wikipedia.org/wiki/8.2_kiloyear_event

      Subsequent coolings have been less pronounced and probably produced by Bond Cycles alone, there being not much more collapsible ice sheet left in the NH, the Greenland IS only waxing and waning slightly in the past 8000 years.

    • Javier : ” I wonder why catastrophic explanations have such a strong appeal to people and are so popular ” ?
      Why don’t you turn the amateur psychology spotlight on to yourself as they seem to appeal to you [ why else are you lingering here ? ] as alternative hypotheses for the Younger Dryas : ” Abrupt cooling results in an increase in the ice load over certain parts of the crust ,leading to an increase in volcanic activity ” .You even mentioned a multi causal catastrophic hypothesis after deriding ” hypothesis driven science” .. This is the second instance of you contradicting yourself .

      • George A. Howard says :
        “Maybe it was the 250 species of animal that disappeared at the YD? That seems kinda special too.”
        ————————–
        And no it was not a small population of stone age hunters. With rock spear tips made by banging rocks on other rocks. That killed every one of millions of large to giant mammals, some of whom were 2-3 times as heavy as their modern cousins. Some of whom were apex predators with very nasty sharp teeth and claws.

        • The predators died off after humans wiped out their megafaunal prey species.

          Humans were responsible for the extinctions, just as in Australia, Eurasia, Madagascar, Hawaii, New Zealand and many oceanic islands. The Pleistocene megafauna had survived prior deglaciation cycles. Only when human hunters pursued them did they die out.

          In Africa, more of the megafauna survived because they were used to humans, with whom they coevolved, so weren’t naive.

        • Size matters! Closing the case in favor of the human (to include Neanderthal and Denisovan) overkill hypothesis. Not that any further evidence should be necessary, given the history of extinctions during the past 125,000 years on every continent and island invaded by humans.

          Body size downgrading of mammals over the late Quaternary

          https://science.sciencemag.org/content/360/6386/310

        • Stone Age hunters of 15,000 years ago were deadly. They had atlatls, to attack from a distance. Probably bows as well. They had fire, to stampede big game over cliffs or into traps. They had dogs. They had cooperative tactics honed for millennia on the Eurasian steppe and tundra.

          They went for the biggest mountains of meat, hide and sinew first, the mammoths. K!ll the cows and the slowly reproducing monsters are history, as would have happened with American bison had one former hunter not rescued them from doom.

          Then came the ancient bison, camels, ground sloths, horses, etc. All driven to extinction in North America by humans hunting there naive, vulnerable beasts.

          • John
            Interestingly, when Native Americans killed large numbers of bison, they tended to take primarily tongues and livers, and just enough hides and muscle for their immediate needs. Thus, they wasted a lot of potential food. That means they could have gotten by with smaller animals to meet their needs. It may be that stampeding bison over ‘jumps’ was easier than stampeding deer or antelope. Thus, the ‘dumber’ animals were preferred game. Strangely, the bison persisted in large numbers while the Pleistocene megafauna disappeared!

          • Clyde,

            The much bigger Pleistocene bison species were wiped out. The wood and plains bison which survived were smaller.

          • John
            I’m aware of the size difference. My point is, if the smaller plains bison provided them with an embarrassment of riches that they couldn’t efficiently use, why would they focus on even larger animals?

      • During the American megafaunal extinction event around 12,700 years ago, 90 genera of mammals weighing over 44 kilograms became extinct. But all the evidence shows that an alleged impact couldn’t have been responsible.

        If an ET impact were the cause, then why did Caribbean island megafauna survive, close to the supposed impact, while those large species far away in Patagonia disappeared?

        The timing of extinctions coincides with human entry into the doomed animals’ habitats.

  20. First setence of second paragraph after this heading

    “What would an Earth impact leave behind?”

    “Looking for more clues, researchers have pored through the widely distributed Younger Dryas Boundary stratigraphic layer.”

    Typo? Should it read researchers have bored…”

      • He and his comrades have claimed to find impact proxies, but in every case, the supposed material has been shown not to result from such a cosmic collision.

        The gang’s “work” has been repeatedly debunked and rebunked.

        • Tillman : ” No impact proxies have been found anywhere ” ….This research paper was published in March of this year : ” Evidence of Cosmic Impact at Abu Hureyra Syria at the Younger Dryas Onset [ 12.8ka] : High Temperature Melting at 2200C ” Nature Communications March 2020 ….Where and in what journal were the researchers findings recently debunked ? This particular paper nature.com/articles/s41598-020-60867-w

          • A pack of lies. Even if there were a Pt signature, it confirms nothing.

            Please learn how real science works.

    • What if the asteroid hit a one mile thick glacier in the North American hemisphere? I do not think that an impact crater would be found, and this would be consistent with a sudden release of water into the Atlantic (no AMOC) and the release of sunlight blocking particles from the asteroid and forest fires. Perhaps a volcano or two decided to do a Mount Pinatubo around the same time.

  21. Hey John Tillman, that’s really authoritative sounding. Except Pete Schultz of NASA, and Ted Bunch retired NASA, are co-authors of the YDIH and have confirmed the proxies as entirely in line with the KT boundary science, which is the standard. Oh, and Andronikov, of Arizona’s Lunar and Planetary lab, confirmed them independently, as have many others. Certainly you have failed to read LeCompte 2012: https://www.pnas.org/content/109/44/E2960.abstract
    Read it very carefully now, so you won’t embarrass yourself in the future making baseless declaratory statements on the internet. https://cosmictusk.com/younger-dryas-impact-hypothesis-bibliography-and-paper-archive/

  22. Tillman : ” No impact proxies have been found anywhere ” ….This research paper was published in March of this year : ” Evidence of Cosmic Impact at Abu Hureyra Syria at the Younger Dryas Onset [ 12.8ka] : High Temperature Melting at 2200C ” Nature Communications March 2020 ….Where and in what journal were the researchers findings recently debunked ? This particular paper nature.com/articles/s41598-020-60867-w

    • As I’ve already pointed out, the paper doesn’t support the debunked :hypothesis”. All it does is show another site with a signature of the Eifel Hot Spot eruption. The supposed glass and tektite “ejecta” aren’t.

      So the paper you keep citing doesn’t support this crackpot “hypothesis”.

      • Its obvious who the lying troll is John . The paper does support the YDIH in the conclusion
        Anyone can read it for themselves . I see Javier has disappeared ..Where is the relevant recent publication in a reputable science journal rebutting the March 2020 Nature Communications Abu Hureyra YDIH paper ? ….There was no abundant volcanic tephra in the soil analyses pointing to any Eifel Hot Spot eruption according to their research …So where is the 2020 citation for this “debunking” paper ? You mentioned iridium as a meteorite signature [ an impact proxy ] which exists in elevated concentrations in that region of Syria . You unwittingly validated a hypothesis you denounced as ” crackpot” . You and Javier were trounced in this debate but of course you never intended debating here in good faith …

        • No debate. Just the facts.

          YDIH zealots have nothing. You never had anything. Your gibberish was promptly shown false in 2008, and it has only gotten worse since then.

  23. John Tillman, trolls like you are embarrassment to science. Clearly interested and capable of understanding, you nonetheless misrepresent and defame people you disagree with. You are simply gross style, with no substance. The 70+ scientists on the YDIH paper are indeed “real scientists” You may disagree them, but that does not demote their status as real. Here’s is one example from many: Dr. Andrew M. T. Moore. Moore led the recent paper, Evidence of Cosmic Impact at Abu Hureyra Syria at the Younger Dryas Onset, kindly cited above by Stu. (The paper is #141 on my bibliography at the Cosmic Tusk: https://cosmictusk.com/younger-dryas-impact-hypothesis-bibliography-and-paper-archive/) Moore is the immediate past President of the Archaeological Institute of America. AIA has over 200,000 members, was found in 1879, and is chartered by Congress. Moore led the dig of Abu Hureyra in the 70’s. He’s a real scientist, John. His qualifications to write this paper exceed those of anyone who would question it. Anyone is welcome to question it, including you, but please do not misinform casual readers here by defaming these researchers as unqualified, and not “real.” Just crawl back in your hole and do some reading, and if you can’t read, listen: https://sevenages.org/podcasts/seven-ages-audio-journal-episode-36-impact-at-abu-hureyra/

    • I have done the reading which you need to do. Adherents of the YDIH cult are the embarrassments to science.

      Real scientists who do real work have repeatedly shown in detail that every single lame argument spewed by these shameless liars is bogus. Yet they keep polluting journals with their mendacious garbage.

      Why? Because it beats working.

      • It is evident on this thread who the liars and embarrassments are ..Who are these ” real scientists ” that have supposedly “debunked” the authors of the March 2020 Nature Communications paper cited by myself and George ? I think the a past president of the Archaeological Institute of America is much more familiar with hard, respectable work than you

        • Stuart,

          I don’t know about you, but George is the Crackpot in Chief, who has made an ill-gotten career out of peddling utter garbage to the poorly educated masses.

      • Stuart,

        Clearly you have not bothered to educate yourself. Please read the innumerable papers from 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019 and 2020 showing what an antiscientific farce is the YDIH.

    • The proponents of this nonsense are even less scientific than climate alarmists, whom I describe in the same terms.

      To be a real scientist, you have to practice the scientific method. It doesn’t matter how many times you pay a journal to publish your hased and rehashed drivel.

    • George,

      Far better than trolls speaking the truth are crackpots in chief such as yourself, here as a tourist to spread your insane garbage, for which low information viewers have rewarded you richly.

      You should be ashamed.

      Although OTOH, you’ve done well for yourself as a sociology grad snookering the gullible folk into buying your total, complete and utter garbage “books”.

  24. Let us invoke that an asteroid hit a one mile thick glacier in Northern American hemisphere and left no impact crater at ground surface. This would not only release massive quantities of ash, but also vast quantities of liquid water that then overcame the natural ice dams holding back the huge water volumes in the Great Lakes area. This would account for massive influxes of fresh water into the Atlantic, shutting down the AMOC, but also causing global cooling from asteroid material and resulting forest fires.

    • Massive influxes of fresh, cold water happen during deglaciations as a matter of course, without ET intervention. Just as armadas of icebergs launch into the North Atlantic during glaciations.

      The main problem with this WAG is that there is no reason to imagine such a highly improbable scenario in the first place, the odds against which are about 2000:1.

      The scheme’s shills suppose that the YD is different from the hundreds of other such cold snaps because of extinctions which appear to have happened during it. But extinctions occcurred before and after it, and always in association with humans.

      Real scientists are convinced to the highest degree of probability that no impact caused extinctions during the YD because the pattern thereof doesn’t support this baseless conjecture. As I keep asking, but no proponent of this unfounded assertion can answer, is why didn’t megafauna on Caribbbean islands die out during the YD, when related species much farther away, to include in South America, did?

      The answer is simple. Because the cold snap didn’t k!ll them off any more than did the prior such excursions in the last glacial termination. Human hunters did, invading continents with naive giant beasts.

      Same as happened in Eurasia, Australia, Madagascar and oceanic islands when modern people with advanced technology and tools arrived.

    • He wont respond directly to that question George …..Nor to any request for scientific research publications supposedly “debunking” the Nature Communications paper we cited . Still waiting John Tillman

    • George and Stuart,

      Of course I respond.

      No, he’s not a real scientist, because he doesn’t practice the scientific method.

      Looking for platinum signatures isn’t science, if the goal is to support an antiscientific, baseless, religious assertion.

      • John Tillman I have no idea who George is ..Of course archaeologists are versed in empirical scientific methodologies ..You however are now debasing this discussion with puerile insults because you have nothing when questioned …Platinum is not the only once trace element ….You admitted iridium is a cosmic impact signature and it was discovered in elevated concentrations at the Abu Hureyra site in Syria along with cobalt ,chromium FE silicides and 2200C melt-glass

        • George Howard, the famous Crackpot in Chief, comments right before you.

          The supposed iridium signature is just as bogus as every other supposed support for this blatantly false assertion.

          Please see my links and quotations below.

          You’ve been taken in by professional liars.

  25. I’m amazed at how many people immediately go with the “impact” premise.

    When it could just as easily have been the result of 1 to dozens of “extraterrestrial” objects of various sizes bursting / arcing / flashing across the upper to lower atmosphere over a variety of time lapses and distances.

    =8-|

  26. For all your YDIH fanboys, here’s the truth (previously posted):

    Geologists, paleoclimatologists, oceanographers and atmospheric scientists do have a very good grasp of what caused the YD and the alternating stadials and interstadials during glaciations and deglaciations (terminations). Cold, fresh water released into the oceans by armadas of icebergs (Heinrich events) or by meltwater from the ice sheets.

    The YDIH and other gods on machines “explanations” are not only wrong, having been repeatedly shown false in detail, but totally unnecessary. They’re time-wasting exercises akin to looking for evidence of phlogiston after the isolation of oxygen or for the humors theory of disease after the discovery of germs.

    The only problem with the meltwater hypothesis before 2005 was ascertaining by which route the flood entered the ocean. It had been shown by 1989 that the usual drainage of the Laurentide Ice Sheet (LIS) via the Mississippi didn’t flow during the YD. Broecker (please forgive him for being the “Father of Global Warming”) in that year suggested the St. Lawrence, which seemed a natural given Niagara’s date of c. 12,000 BP. But analysis of its channels and sediments didn’t really show any clear sign of such an ice-dammed outwash flood. And in any case, proglacial meltwater Lake Agassiz was SW of the LIS. An arm of it could have hooked around the southern face of the retreating LIS, but the lay of the land was against this possibility.

    And there the situation stood until 2005, when Tarasov and Peltier proposed that the meltwater discharge was not into the Gulf of Mexico or North Atlantic, but into the Arctic Ocean, via the MacKenzie River drainage.

    https://www.atmosp.physics.utoronto.ca/~peltier/pubs_recent/Lev%20Tarasov%20and%20W.R.%20Peltier,%20Arctic%20Freshwater%20Forcing%20of%20the%20Younger-Dryas%20Cold%20Reversal,%20Nature,%20435,%20662-665,%202005.pdf

    The last deglaciation was abruptly interrupted by a millennialscale reversal to glacial conditions, the Younger Dryas cold event. This cold interval has been connected to a decrease in the rate of North Atlantic Deep Water formation and to a resulting weakening of the meridional overturning circulation owing to surface water freshening. In contrast, an earlier input of fresh water (meltwater pulse 1a), whose origin is disputed, apparently did not lead to a reduction of the meridional overturning circulation. Here we analyse an ensemble of simulations of the drainage chronology of the North American ice sheet in order to identify
    the geographical release points of freshwater forcing during deglaciation. According to the simulations with our calibrated glacial systems model, the North American ice sheet contributed about half the fresh water of meltwater pulse 1a. During the onset of the Younger Dryas, we find that the largest combined meltwater/iceberg discharge was directed into the Arctic Ocean. Given that the only drainage outlet from the Arctic Ocean was via the Fram Strait into the Greenland–Iceland–Norwegian seas, where North Atlantic Deep Water is formed today, we hypothesize that it was this Arctic freshwater flux that triggered the Younger Dryas
    cold reversal.

    Perhaps their paper didn’t get the respect it deserved because the North Atlantic paradigm ruled so strongly. The chain of lakes from Manitoba across the NW Territories, marking the retreating LIS edge stared everyone in the face, but like geographers since AD 1500 looking at South America and Africa before Wegener, had eyes but couldn’t see.

    In any case, two years later Firestone and unindicted coauthors perpetrated their ET impact hypothesis, if the wild conjecture may be so designated. It was promptly shown false, and has been repeatedly since then, but its easy career-making potential meant that it took on a zombie-like existence, with a voodooist cult following. It lurches along, from one new lame excuse to another.

    Even loopier “hypotheses” have been floated, in this debased age when just about anything but reality gets published readily. Broecker’s former coauthor Kennett even deserted to the Dark Side of the farce.

    But a few real scientists over the years have investigated the MacKenzie River hypothesis, and repeatedly confirmed it. Both observations and simulations of drainage and the effect on the Atlantic meridional overturning circulation (AMOC, the zonally-integrated component of Atlantic surface and deep currents). and atmospheric circulation supported it.

    After this 2018 paper, the case is effectively closed, as it long ago should have been, had the scientific method ruled. Science is never settled, of course, but no present alternative hypothesis can compete with this ice-rafted deluge of valid evidence. The iceebergs and meltwater deliver cold, fresh water to where it will have the most effect, and the flow lasts hundreds of years, solving the issues of duration and amplitude of YD cooling.

    https://www.nature.com/articles/s41561-018-0169-6?proof=trueMay.

    A period of cooling about 13,000 years ago interrupted about 2,000 years of deglacial warming. Known as the Younger Dryas (YD), the event is thought to have resulted from a slowdown of the Atlantic meridional overturning circulation in response to a sudden flood of Laurentide Ice Sheet meltwater that reached the Nordic Seas. Oxygen isotope evidence for a local source of meltwater to the open western North Atlantic from the Gulf of St Lawrence has been lacking. Here we report that the eastern Beaufort Sea contains the long-sought signal of 18O-depleted water. Beginning at ~12.94 ± 0.15 thousand years ago, oxygen isotopes in the planktonic foraminifera from two sediment cores as well as sediment and seismic data indicate a flood of meltwater, ice and sediment to the Arctic via the Mackenzie River that lasted about 700 years. The minimum in the oxygen isotope ratios lasted ~130 years. We suggest that the floodwater travelled north along the Canadian Archipelago and then through the Fram Strait to the Nordic Seas, where freshening and freezing near sites of deep-water formation would have suppressed convection and caused the YD cooling by reducing the meridional overturning.

    The scientific method still survives in a few refugia.

    Comparing the last termination with the previous six going back to the Mid-Pleistocene Transition (the switch from ~40,000-year glacial cycles to those averaging ~100,000 years) is instructive, but beyond the scope of a comment. The four before Termination VII occurred during the transition, ie ~700 Ka to 1.2 Ma. Suffice it to say, that stadials (coolings) caused by meltwater and iceberg armadas are evident in all of them, although not all have coolings as pronounced and long-lasting as the YD. Those that do reflect similar Milankovitch cycle alignments, hence summer solar insolation regimes. Those which don’t experienced higher insolation.

      • Whatever hypothetical other contributing factors might be proposed, the fact remains that flow of ice sheet meltwater via the MacKenzie drainage for 700 years from the start of the YD affected the AMOC.

        The paper on Texas cave sediments cited by David Middleton shows yet again that there is no evidence whatsoever supporting a catastrophic impact, and all the evidence in the world against it.

        Volcanic origin for Younger Dryas geochemical anomalies ca. 12,900 cal B.P.

        https://advances.sciencemag.org/content/6/31/eaax8587

        Each of these four possible triggers for the YD event is complex, and there is not a clear consensus as to which mechanism or combination of these events initiated the YD cold period. Of these explanations, the impact hypothesis has received the most attention, but problems plague this hypothesis. The fundamental issue is delineating if the markers used to support the hypothesis extracted from the YD layers at various sites are really impact markers (1, 11). The grains interpreted as carbon spherules and “elongates” and “glass-like carbon” have been instead identified as fungal sclerotia common in Northern Hemisphere forest litter and soils (12). In addition, the micrograins interpreted as hexagonal nanodiamonds from YD sites of Murray Springs (AZ) and Arlington Canyon on Santa Rosa Island (CA) are instead assessed as graphene/graphene aggregates (13). These disagreements are compounded by a lack of valid age control at many of the YD boundary (YDB) layer sites. It is now thought that only 3 of the 29 sites dated to the onset of YD event were within the prerequisite time period. Furthermore, there are problems in that the reproducibility of observations at the YD level has been questioned for the presence of magnetic grains, spherules, and Ir enrichments. Surovell et al. (14) failed to duplicate the magnetic grain or microspherule peaks associated with the YD basal boundary. Thus, there is a lack of consensus on how to interpret the impact markers.

        Highly elevated concentrations of Ir together with enrichments of other highly siderophile elements (HSEs) (Os, Ir, Ru, Pt, Pd, and Re) in nearly chondritic ratios are considered indicators of a meteoritic contribution delivered when an extraterrestrial (ET) object affects the Earth or airbursts over it (15). These HSE enrichments may be from an external source because the Earth’s crust has 1 (18), such that small amounts of ET material added to continental crust will shift the 187Os/188Os ratios of the hybridized material to lower values.

        The cause of the elevated HSE concentrations and the Os isotopic ratios in YD layer sediments remains equivocal and has been used to both support and negate the YD impact hypothesis. For example, Petaev et al. (19) found a Pt enrichment accompanied with an extremely high Pt/Ir but Al-poor signature in the Greenland Ice Sheet Project 2 ice core at the Bølling-Allerød/YD transition period, which they interpreted to be consistent with an ET impactor. Also, the elevated Pt abundance anomalies of 100 to 65,600 parts per trillion (ppt) at the onset of the YD in sites from North America is purportedly consistent with the Greenland ice core Pt data (20). Moore et al. (9) found Pt and Pd/Pt anomalies in the YD basal layer in South Carolina. These data are used to support a model of wide-ranged atmospheric input of platinum-rich dust during the YD, potentially related to a bolide impact or airburst. In contrast, the 187Os/188Os ratios obtained on YD basal boundary layers from widely dispersed locales in North America and Europe have largely been similar to those for continental crust or seawater with no evidence of unradiogenic 187Os/188Os ratios from ET or mantle sources, both having 187Os/188Os ratios of 0.11 to 0.13 (21, 22). This is exceptional because <1% of ET material from an impactor mixed into continental crust would shift the resultant hybridized material away from terrestrial crustal 187Os/188Os values toward the less radiogenic values of 187Os/188Os chondrites (17). Only one site has been identified with an unradiogenic Os signature, with an 187Os/188Os ratio of 0.4 for the YD basal boundary layer at Melrose, PA (22). This signature is attributed to surface films on glass spherules with highly elevated Os concentrations and unradiogenic 187Os/188Os ratios of 0.113 to 0.121 that may have been caused by mobilization of Os within a bolide fireball and possibly terrestrial in origin and ejected as molten material following impact (22). An important question remains: Why are low 187Os/188Os ratios found only at one site and not more widely dispersed if it is derived from impact or air burst of a bolide?

        The above studies show that there is no clear consensus on the interpretation of HSE concentrations and 187Os/188Os compositions of YD basal boundary sediments (21, 22). A better understanding of their systematics is crucial for determining the role, if any, of a bolide event for the YD cooling and to refine conclusive evidence in the rock record for bolide impacts. To further examine this issue, we measured HSE abundances and 187Os/188Os isotope ratios in samples from Hall’s Cave, TX, including those from the YDB. Hall’s Cave formed in the Segovia Formation of the lower Cretaceous Edwards Group and contains sediments dating from 20,000 years before the present (B.P.) to present (23). The cave has a consistent depositional environment with minimal reworking or disturbance over this time period (23). The stratigraphy is well dated based on 162 accelerator mass spectrometry (AMS) 14C dates from vertebrate fossils, snails, charcoal, and sediment chemical fractions (23, 24). The YD basal boundary layer at Hall’s Cave also contains purported ET proxies including nanodiamonds, aciniform soot, and magnetic spherules (25). Here, we present Os isotopes and HSE abundances from the YD basal boundary strata in addition to layers above and below that horizon. Our measurements span ~4000 years of sediment deposition at Hall’s Cave. The HSE chondrite-normalized patterns combined with 187Os/188Os at different levels within this section at Hall’s Cave including the YD basal boundary layer show a repeating record of Os concentration enrichment. Multiple occurrences above and below the anticipated YD basal boundary layer bring into question the single impact theory for the YD climate event. Instead, we propose that the five layers containing HSE enrichments and Os isotopic signatures represent volcanic aerosols and cryptotephra contributed from distant volcanic eruptions over the ~4000 years.

        • Mr. Tillman for the umpteenth time , if the iridium ,chromium cobalt and meltglass cosmic impact signatures identified at the Abu Hureyra site in Syria and reported in the March 2020 Nature Communications paper are ” bogus” where is the RECENT rebuttal research published in a reputable scientific journal ? …Answer the question and specify the publication ..Your Gish Gallop tactics [ above ] streaming slabs of irrelevant information are not working and you want others to believe the authors of that research paper are ” professional liars” ….Thats absurd and defamatory …..You have ,moreover, contradicted yourself – departing from emphatically stating the YD was caused by volcanism to ” Each of these four possible triggers for the YD event and there is not a clear consensus as to which mechanism or combination of these events initiated the YD cold period ” .Your turgid text above .even acknowledges : ” may have been caused by mobilization of Os with a bolide fireball and possibly terrestrial in origin and ejected as molten material following impact ” ..

          .Made up your mind yet or did you intend to blow the smoke and tilt the mirrors on this thread from the outset ?

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