Exploring abrupt climate change induced by comets and asteroids during human history

The Beeb’s Simon Redfern picks up Harvard evidence for Younger Dryas Boundary Event

BBC link 


BBC News


1 August 2013 Last updated at 14:52 ET

Ice core data supports ancient space impact idea

By Simon Redfern

BBC News

New data from Greenland ice cores suggest North America may have suffered a large cosmic impact about 12,900 years ago.

A layer of platinum is seen in ice of the same age as a known abrupt climate transition, US scientists report.

The climate flip has previously been linked to the demise of the North American “Clovis” people.

The data seem to back the idea that an impact tipped the climate into a colder phase, a point of current debate.

Rapid climate change occurred 12,900 years ago, and it is proposed that this is associated with the extinction of large mammals such as the mammoth, widespread wildfires, and rapid changes in atmospheric and ocean circulation.

All of these have previously been linked to a cosmic impact, but the theory has been hotly disputed due to lack of clear evidence.

New platinum measurements were made on ice cores that allow conditions 13,000 years ago to be determined at a time resolution of better than five years, report Michail Petaev and colleagues from Harvard University. Their results are published in the journal Proceedings of the National Academy of Sciences.

A 100-fold spike in platinum concentration occurs in ice that is around 12,890 years old, at just the same moment that rapid cooling of the climate is indicated from oxygen isotope measurements, at the start of a climatic period called the “Younger Dryas”.

The Younger Dryas started and finished abruptly, and is one of a number of shorter periods of climate change that appear to have occurred since the last glacial maximum of 20,000 years ago.

Each end of the Younger Dryas period may have involved very rapid changes in temperature as the climate system reached a tipping point, with suggestions that dramatic changes in temperature occurred over as short as timescale as a decade or so.

Asteroid apocalypse?The observations lend credence to earlier, disputed, reports that finds of microscopic grains of diamond and a mineral called lonsdaleite in lake sediments dated to the same time were identified with a possible meteorite impact.

Those measurements resemble the most recent observations of remnants of the Tunguska meteorite impact in Siberia, reported last month.

Sphere-shaped particles have also been identified at many localities in sediments dating to this event, most recently reported this month by a team led from Canada in the Journal of Geology. Such particles are characteristic of the rapidly heated and cooled splatter of material thrown up when meteorites hit Earth.

While the platinum data and the spherical particles add to evidence for an impact event, doubters have pointed out that, as yet, no impact site has been identified.

It has been suggested that debris thrown into the atmosphere in an impact tipped the Earth into global cooling at a rate as rapid as the global changes in climate in the reverse direction seen in the last century.

Such rapid climate change makes it difficult for ecologies and societies to adjust: It is the fluctuation that has been invoked as the cause of the extinction of massive mammals (megafauna) like the mammoth, and native cultures such as the Clovis people in North America.

The possible role of cosmic impacts in causing huge changes to life on Earth is receiving increased attention. The mass extinction 66 million years ago that wiped out the dinosaurs is generally believed to be linked to a space strike in southern Mexico’s Yucatan Peninsula.

Recently, a group of scientists led by Eric Tohver at the University of Western Australia reported that the biggest extinction of all, which occurred 252.3 million years ago at the end of the Permian period, could be explained by an asteroid impact in Brazil.

Nasa is now focusing resources towards detection of future Earth-threatening asteroids, receiving over 400 responses to their recent request for ideas to feed into their Asteroid Grand Challenge, in which they hope to redirect a space rock and send humans to study it.

12 Responses

  1. I LOVE the headline:

    A comet DID wipe out first North American prehistoric humans: Ice core data suggests a cosmic impact killed off Clovis people

    The all-caps “DID” is great!

    Shoot down the Daulton Gang, folks!

    The DID says that in spite of the freaking naysayers, the evidence is on, and YOU GUYS ARE WRONG! EAT CROW, BABY!

  2. It would be great if some of you guys could tone it down a bit on this subject, especially where you appear to be clueless. You aren’t doing your advocacy of this subject any good. If not, I suggest you prepare yourself for a moderate amount of disappointment at some time in the future. Thanks.

  3. TEL,

    Demands of civility in the face of adverse and repeatable scientific evidence, when the skeptics — “The Dalton Gang” et al — have engaged in variously;
    o Argumentum ad hominem,
    o Argumentum ad nauseam, and
    o Argumentum ad verecundiam,
    is rich.

    It is so rich that it deserved the “And your Momma” which it is is getting from YDB proponents.

  4. Yup. I left out “And your Momma.”

    Thanks for that, Trent.

    And, TLE, who says we aren’t aware there will be disappointment in the future? Of course there will be. But so far, even when the skeptics came out with something it was so flawed, there hasn’t BEEN any reason to be disappointed. The YDB Team has a good game plan and they are on the right track. Beyond that I’ve got no horse in the race. It SEEMS to me this hypothesis is correct, so I come and watch the game unfold. Where the facts lead, that is where the facts lead. If I am disappointed in facts and evidence I am frequenting the wrong blog.

    The amazing thing is that this thing that seemed to be less than a 50-50 shot at best keeps on getting so many independent verifications – from researchers and evidence both. And the opposition has been such weak and under-evidenced kibitzers, yet their stridency never fails – along with the misguided, completely un-objective science editors who so readily declare the YDB dead in the water with so little to go on. Advocacy in science such as theirs is a really stupid idea – because the advocacy adds nothing to the real discussion and only sets themselves up for failure – and eating crow.

    DO notice how high the Richard Kerr calendar has gotten (upper left), without a peep out of the perp. . . 2-1/2 years plus. Not even a “maybe there is something to this, after all…” He shouts from the yardarm when he thinks his side has hit something with their pea shooters, and then he goes all silent when the facts shut him up. His silence only shouts out loud and clear how wrong he was.

  5. And, TLE, I am not clueless. I trust that in calling me that you were carried way by emotion or whatever, so I don’t take offense.

    And not meaning to offend you in response, but that I don’t pray to your god or Mother Church’s datings of <4004 BCE means only that I am not a Christian who believes the literal truth of a book written by people with an agenda, then translated by others with an agenda.

    As I said: Where the facts lead, that is where the facts lead.

    In addition, I've looked into the Bible myself, for decades, and I simply find it not to be a wagon I choose to ride in. Why not? Facts. Facts of which I am not clueless about.

    That the facts haven't supported the Bible for as long as science has existed seems to not be enough to convince some people that they themselves are clueless and have backed the wrong horse. So they pick holes in Evolution, which is easy to do, since A:) it tackles a LOT of areas, and B.) it DOES have holes in it – but that doesn't mean that by default the Bible is correct. It only means that Evolution isn't fully developed yet. And as long as Evolution is tied to gradualism it will always BE inadequate. ID and Creationists pointing out flaws in the major counter argument doesn't make their own argument any sounder. But it wins over the limited minds of those who don't look into the facts of the matter.

    …All those layers of sediment — they can be counted by a 5-year-old, and those layers say that the Earth is much older than your 4004 BCE. Those should be a clue that something is wrong in Bible Land and its dating. It doesn't take a rocket scientist to count them. Just what happens when a Bible believer counts them? When he approaches a sedimentary layer count of 4004 and sees that there are a LOT more below that, does he stop and say, "Well, I only counted 4003, so the Bible is right, more or less"? Or does his mind shut off, in denial?

    We can all count, can't we? And if we count, are we then less clueless?

  6. (Sigh) Steve, let it be. We already know you don’t believe the Bible narrative so why reiterate your reasons?

    Science is paradigmatic and interpretive models are built on the presuppositions of the paradigm. You have chosen the naturalist paradigm to hang your hat on because you place your faith in materialism. Those of us who hold to a young-earth paradigm based on a straight-forward reading of the Old Testament, which includes a growing number of PhDs who are more qualified in their subject matter than either you or I, do so because we have faith that God has preserved an accurate record of the earth’s history.

    The bottom line is that neither side of the issue can empirically prove their point. For every piece of evidence that you provide supporting a tenet of gradualistic naturalism, I can provide a counter argument from my presuppositions. We hold to different interpretive models by faith in something. I have come to reject deep-time premises, even though I received my degrees in evolutionary zoology and uniformitarian geology (uniformitarianism wasn’t discredited back then)and have come to accept the Biblical model as more credible and reasonable.

    I think it would be better for all if we stick to the purpose of this site and pore over the accumulating evidence of an ancient impact. Whether it occurred 12.9 ka ago or less than 5 ka doesn’t really matter to me. The forensic evidence all seems to be pointing to an impact within human history. Whether this unobserved event can inform the risk assessment of a near future impact remains to be seen.

  7. Terry –

    You don’t get off that easily. Is it possible to count sediment layers or not? And if the layer count exceeds 4004 BCE by many thousands of layers, what say you?

    It’s not rocket science, and it takes no presupposed paradigm. Evidence is evidence, facts are facts – irrespective of paradigms – unless one chooses to ignore facts. In which case reason and logic are held to be unimportant, and in which case there is no logical case to be made.

    If you can’t explain the number of layers, dodging the issue and shifting to some weakness in evolution only shows the weakness in your own paradigm. BTW, I don’t accept at all as presently presented. There ARE too many weaknesses in it. But that doesn’t mean that the explanations default to the Biblical story. And, BTW, the Biblical 4004 BCE story is in itself a paradigm, one that gullible people still accept because they haven’t taken the time to count the layers – or choose to ignore the layers.

    When there are millions of layers, what explanation do you present? (No shifting to weaknesses in evolution; just answer the question.)

  8. Terry –

    This much of what you say is certainly true: “Science is paradigmatic and interpretive models are built on the presuppositions of the paradigm.”

    Science is NOT solely a collection of facts – as some have asserted on other blogs and other places. Science is the attempt to understand the natural world, and as such facts are abetted by interpretations – interpretations that often, over the decades, are shown to be inadequate.

    And, one interpretation leading to another, that collection becomes a paradigm. And paradigms do get superceded – such as the process now going on about the YDB and Clovis man.

  9. Terry –

    “The bottom line is that neither side of the issue can empirically prove their point.”

    In science it is only possible to PROVE a hypothesis to NOT be true, by what is known as falsification. It is not possible to actually prove a hypothesis true – only at best to say that “so far” no evidence has arisen to show it is untrue. I refer you to Richard Feynman’s video about the scientific method (several copies on YouTube).

    “For every piece of evidence that you provide supporting a tenet of gradualistic naturalism, I can provide a counter argument from my presuppositions.”

    In this you display ignorance of what I’ve written. Such as on this thread: “And as long as Evolution is tied to gradualism it will always BE inadequate.” Where in that do you read that I support “gradualistic naturalism”?

    You don’t.

    “We hold to different interpretive models by faith in something. I have come to reject deep-time premises, even though I received my degrees in evolutionary zoology and uniformitarian geology (uniformitarianism wasn’t discredited back then).”

    Uniformitarianism is discredited???? You amaze me, saying you ” “studied evolutionary soology and uniformitarian geology,” if you think uniformitarianism is discredited. In what circles? The 4th Baptist Church of Dallas? In scientific circles uniformitarianism is as strong as ever. You are jumping the gun making such a claim.

    I will repeat: I disagree with its adherents that uniformitarianism – gradualism is sufficient. It is NOT sufficient. It needs some level of catastrophism. What level? It is too early to say.

    But one thing is certain is this: 12,800 years ago some catastrophic event occurred, whether triggered by a comet or by some tipping point in the climate. For now, either one is only an interpretation of the facts, but the facts are undeniable: More than 6,000 years earlier than the religious believers say the Earth was formed, the climate changed from warm to cold, essentially overnight. People have one-by-one counted the layers in ice cores and sediments, and the facts are the facts: The Earth was around more than 6,017 years ago.

    That is not an interpretation; it is a quantified fact.

  10. Tough call, I love both you guys, Steve and Terry. I see you as poles of my own understanding.

    Fight it out?!


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