Sudden Clovis climate death by comet – "bogus"

UPDATE 3/12/12 – a new study presents very strong evidence for the comet theory, see here

Bishop Hill alerts us to this news item in Miller-McCune, a policy and research website. It seems the scientific claims can’t be replicated by others…but wait for the kicker.

OK, having read that primer, it looks like a slam dunk for falsification, right?

Yet, the scientists who described the alleged impact in a hallowed U.S. scientific journal refuse to consider the critics’ evidence — insisting they are correct, even though no one can replicate their work: the hallmark of credibility in the scientific world.

“We are under a lot of duress,” said Kennett. “It has been quite painful.” So much so, that team members call their critics’ work “biased,” “nonsense” and “screwed up.”

“It is very peculiar,” Holliday said. “They propose an idea, a study contradicts it, then they criticize the scientists or the work.”

Hmm, where have we seen this sort of behavior before? Man o’ mann,  I wish I could remember where contradictory peer reviewed scientific replication was dismissed as “biased,” “nonsense” and “screwed up.”.

But it reminds me of what might go on in scientific circles above Monks restaurant:

The news item in Miller-McCune is highly recommended reading

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Anthony you missed the real kicker which is in the comments section to the article:

Eric Steig 2 days ago
Having been the victim of attacks on my character, as a consequence of publishing something that appears to go against the grain (though in my case it has turned out to be correct: O’Donnellgate), I am pretty sympathetic to Kennet and his colleagues, and I’m disappointed to see my colleagues jumping on the bandwagon of declaring foul. I have myself been skeptical of the comet hypothesis for the Younger Dryas (see , but I have articulated my concerns on the basis of the science, not on insinuations about the character or hidden motivations of the scientists involved. The fact is that the scientific process works in weeding out untenable ideas, and there is no reason to call it a ‘scandal’ when an idea (outrageous or not) turns out to fall into disfavor.

Being a wordy fellow the good Dr. Stieg needed a second comment to complete his statement:

Eric Steig 2 days ago
I think it would be helpful if people didn’t cry ‘foul’ the second an idea is shown to be wrong. Having been the victim of specious attacks on my character, for making the unforgivable mistake of publishing something that goes against the grain (see RealClimate on the Comet Hypothesis), but on the basis of factual evidence, not on the basis of speculation about people’s character or supposed motivations.

Douglas DC

Just keep saying it- until we believe it….
You hope…

“Not a lie, if you believe it”.
This reminds me…
Now I’ll give you something to believe. I’m just one hundred and one, five months and a day.’
‘I can’t believe that!’ said Alice.
‘Can’t you?’ the Queen said in a pitying tone. ‘Try again: draw a long breath, and shut your eyes.’
Alice laughed. ‘There’s no use trying,’ she said ‘one can’t believe impossible things.’
‘I daresay you haven’t had much practice,’ said the Queen. ‘When I was your age, I always did it for half-an-hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast”.

(5. Wool and Water, Through the Looking Glass, by Lewis Carroll)

ShrNfr

An open and Clovis case if you ask me.

The truly sad thing is, the incompetence in science is so widespread that you can’t trust the academics on either side of this debate. They all assume too much (that is in fact wrong), so points and counterpoints are just so much rank speculation.

Laurie Bowen

I always like to to a Google time line for some of the subject you bring up even though one must “consider the source”. so I did a Google timeline for Cycle of Cosmic Catastrophes: and I attempt to post the link . .
http://www.google.com/search?q=Cycle+of+Cosmic+Catastrophes&hl=en&sa=X&tbs=tl:1,tl_num:80&prmd=ivns&ei=TMnSTaeVO8mgtgeazbiUCg&ved=0CGoQywEoBA&biw=1004&bih=594
I actually, would say (postulate) that if a big asteroid ever hit earth it . . . . would have gone “in” where the Dead Sea is and come out where the Yellow Stone is . . . like a giant gun shot wound . . . but, that would simply be a guess with no real evidence to prove it except my wondering mind about things like this . . . . hoping of course it would make a logical possiblity . . . .
Long, long, long ago . . . no one would ever have thought (or believed) a rock could burn . . . but we now know it is called coal . . .

James Schrumpf

The alarmists do have their heads on a swivel, don’t they:

“It does feed distrust in science,” says Wallace Broecker, a geochemist at Columbia University and an international dean of climate research. “Those who don’t believe in human-produced global warming grab onto it.”

I’d say everyone who likes to see good science should be appalled at this, not just CAGW skeptics. Of course, maybe the alarmists just see it as “business as usual.”

Tamara

An interesting quote from the article: “Kennett seems fixated on the Younger Dryas, Broecker added, “He won’t listen to anyone. It’s almost like a religion to him.””
Like a religion…hmmmm.
Also interesting:
““It does feed distrust in science,” says Wallace Broecker, a geochemist at Columbia University and an international dean of climate research. “Those who don’t believe in human-produced global warming grab onto it.””
Does that mean that only GW skeptics distrust dishonest science? Thanks for the compliment!

“Man o’ mann, I wish I could remember where contradictory peer reviewed scientific replication was dismissed as “biased,” “nonsense” and “screwed up.”.
But Anthony, your peer-reviewed scientific replication surfacestations work didn’t contradict the extant instrumental temperature records, it affirmed them!
I really don’t think you need to worry about it being the subject of accusations from the consensus such as “biased,” “nonsense” and “screwed up.” If anything, many think its publication demonstrates remarkable integrity since this affirmative replication completely undermines what you have always contended it would show. Well played, sir, well played! Bravo.

> The news item in Miller-McCune is highly recommended reading
Indeed ! Did you see the comment by Eric Steig (or someone using that name):

Having been the victim of attacks on my character, as a consequence of publishing something that appears to go against the grain (though in my case it has turned out to be correct: O’Donnellgate), I am pretty sympathetic to Kennet and his colleagues, and I’m disappointed to see my colleagues jumping on the bandwagon of declaring foul. I have myself been skeptical of the comet hypothesis for the Younger Dryas (see http://www.realclimate.org/index.php/archives/2009/01/the-younger-dryas-comet-impact-hypothesis-gem-of-an-idea-or-fools-gold/ ), but I have articulated my concerns on the basis of the science, not on insinuations about the character or hidden motivations of the scientists involved. The fact is that the scientific process works in weeding out untenable ideas, and there is no reason to call it a ‘scandal’ when an idea (outrageous or not) turns out to fall into disfavor.

I think I converted the HTML errors into something close to what Steig intended, they were badly messed up by human and silicon hands.
The story and substories are amazing – on many levels.

TomG(ologist)

Queen:”I daresay you haven’t had much practice,’ said the Queen. ‘When I was your age, I always did it for half-an-hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast”.
Douglas Adams: “If you’ve done six impossible things today, why not round it out with breakfast at Milliways: The Restaurant at the End of the Universe”.
The curious(er and curiouser) thing comparing guys like Steig with H2G2 is that Adams took care to make his ludicrous ideas plausible – but these guys can’t seem to help making plausible ideas ludicrous.

Gator

Hey Laurie! Sorry to pick nits…
“Long, long, long ago . . . no one would ever have thought (or believed) a rock could burn . . . but we now know it is called coal . . .”
Coal is not a rock and it is not a mineral, it is organic. I know Wiki will call it a rock, but consider the source. In geologic terms, a rock is a aggregate of minerals.

lowercasefred

I remember listening to Arthur Meyerhoff explain why continental drift was impossible. Immanuel Velikovsky was a crank, but he noticed important things that others ignored.
“Stones do not fall from the sky.”
Let science work its way without personalities getting involved.

Hoser

In Greenland ice cores, 10-Be levels rise again during the Younger Dryas to almost the same concentrations as during the Ice Age and then fall to current low levels when the Younger Dryas ended. So how did cosmic rays know about the Younger Dryas? Just coincidence?

James Sexton

boballab says:
May 17, 2011 at 11:54 am
Anthony you missed the real kicker which is in the comments section to the article:
Eric Steig 2 days ago
Having been the victim of attacks on my character, as a consequence of publishing something that appears to go against the grain (though in my case it has turned out to be correct: O’Donnellgate),……..
===================================================
lol, oh my, reality is so hard for some people to deal with.

Laurie Bowen

Hey Gator! “Sorry to pick nits…”
“Long, long, long ago there were no such things as minerals, just earth, fire, air, and water . . . I think that how that goes. . . .

Myrrh

Didn’t the Clovis ‘disappear’ before ‘the comet’ which then began the Younger Dryas?

Buffoon

There is a concrete takeaway from this, and it is quite important. To come to a reasonable conclusion based on observations of a reasonable methodology, and then to be (apparently) refuted in a later study is NOT malfeasance. It’s science.
Everything on top of that, advocacy, personal attack, public dismemberment.. That’s malfeasance.

KnR

even though no one can replicate their work: the hallmark of credibility in the scientific world.’ expect it would seem climate science where saying trust me on this, seems to be enough.

Dennis

Are you a liar?
How many planets are there?
If you say eight, you are hip to the new consensus.
If you say nine, you are either uninformed or love Disney characters more than scientific orthodoxy.
But what did you say 20 years ago? You probably said nine. Does that make you a liar?

Al Gored

Interesting topic. But one thing has always bothered me about this whole ‘Clovis disappearance’ concept.
They link the disappearance of the Clovis people with the disappearance of the “mammoths they fed on” as written here. That is the first problem. Mammoths were only ONE of their prey. (And mammoths survived on places like Wrangell Island
much later UNTIL human hunters got there.)
But ‘Clovis people’ are identified by their giant spearpoints. So whether those people actually disappeared or they just changed to different spearpoints (for increasingly smaller prey after the megafauna were mostly gone) is another whole question.
No doubt this was a period of great ecological change, driven by both climate and human activity. Much too complex for a simple ‘Lone Comet’ theory.

MarkW

I started reading the article to try and find what the evidence was that hadn’t been replicated. The author didn’t get around to that tidbit until well over halfway through the article. I barely made it that far. I haven’t seen so much invective and so little science since the last time I read a post at Real Climate.

Anything is possible

Mods : I did attempt to post this in Tips and Notes (honest) but it appears to be full.
Experimental evidence appears to support the mechanism for Svensmark’s GCR theory…..
http://science.au.dk/en/news-and-events/news-article/artikel/forskere-fra-au-og-dtu-viser-at-partikler-fra-rummet-skaber-skydaekke/

Hoser says:
May 17, 2011 at 1:39 pm
So how did cosmic rays know about the Younger Dryas? Just coincidence?
Isn’t it so that in colder times less snow is falling, increasing the relative amount of 10Be in the ice?

Peter Wilson

Interesting that Eric Steig pops up as a commenter, claiming to have also been a victim of character assassination for publishing something going “against the grain”, and offering support for the comet theory.
The parallels are just too obvious – the intransigence in the face of overwhelming refutation, the claim to victimhood, the re writing of history. But for Steig to claim he was publishing something “that appears to go against the grain” is just silly. The whole reason he got the attention he did, and so obviously craved, was that his work went very much WITH the grain, adding yet another continent to the global warming cause.

Pompous Git

rustneversleeps said @ May 17, 2011 at 12:53 pm
“But Anthony, your peer-reviewed scientific replication surfacestations work didn’t contradict the extant instrumental temperature records, it affirmed them!”
So you are saying that instead of accepting what the data said, Anthony should have been a Real Climatologist and fudged the data? Wierd…

Jeremy

Apparently, Eric Steig thinks that another published paper questioning his work is a form of character assassination?
Is that even Eric? It’s hard to believe someone as smart as he is doesn’t know when to quit digging the hole he’s stuck in.

DesertYote

Don’t have time to read all the posts, gotta code review in a few, so just a quick comment that might be repeats of what others have written.
The disappearance of the Clovis Culture might just be an artifact of the data that has been preserved in the scant material that has survived. A lot of evidence sujest that the Clovis people just changed and moved on to bigger and better things..
As for the mega-fauna extinction, a highly advanced predators specifically designed to hunt mega-fauna appeared in North America. Everyone seems to forget this fact. I guess because it is contra-narrative. I am not talking about the Clovis people. The predator I am referring to is one of my old world cousins, ol’ C. lupus.

Laurie Bowen

Buffoon says:
May 17, 2011 at 2:02 pm “There is a concrete takeaway from this, and it is quite important.”
The take away . . . was a massive worldwide regressive tax . . . an artificially high price of energy . . . . and artificially low supply of energy for the majority. . . and a massive money laundering program . . . through cap n trade . . . coupled with no apportionment and a very low profit tax rate . . . for the minority.
All based on bogus Science that resulted in claims that amounted to “there is just not enough to share without destroying us all!” (in my opinion)!

Shrnfr

@Laurie, it depends on your tradition. In the indigenous Tibetan religion of Bon, those 4 “essentials” surround a 5th known as space.

Eric Anderson

Jeremy said: “Is that even Eric [Steig]? It’s hard to believe someone as smart as he is doesn’t know when to quit digging the hole he’s stuck in.”
No, it sounds very much like him. That has been his attitude from the outset. Pretty pathetic.

Hoser

Ferdinand Engelbeen says:
May 17, 2011 at 2:24 pm
Isn’t it so that in colder times less snow is falling, increasing the relative amount of 10Be in the ice?
______________________
Yes, except that it is so much more 10-Be that I doubt both the role of the sun and less snow. It makes me wonder about the GCR flux at the heliosphere. We do know that the GCRs are anisotropic and variable. I’m not sure we know just how variable GCRs can be and what controls that. Perhaps the galactic magnetic field.

Al Gored

DesertYote says:
May 17, 2011 at 2:47 pm
“As for the mega-fauna extinction, a highly advanced predators specifically designed to hunt mega-fauna appeared in North America. Everyone seems to forget this fact. I guess because it is contra-narrative. I am not talking about the Clovis people. The predator I am referring to is one of my old world cousins, ol’ C. lupus.”
Well, since the first people in North America, like all the hunter-gatherers in Eurasia, had tame wolves (dogs), imagine the combined effect. Then add fire. This combination seems to be almost always overlooked.

jorgekafkazar

Gator says: “Coal is not a rock and it is not a mineral, it is organic. I know Wiki will call it a rock, but consider the source. In geologic terms, a rock is a aggregate of minerals.”
Wiki is not a synonym for Wankapedia, Gator.

jorgekafkazar

Eric Anderson says: “No, it sounds very much like [Steig]. That has been his attitude from the outset. Pretty pathetic.”
From what I recall, Dr. Steig was fairly approachable early on, but became less so as he adopted an increasingly defensive attitude.

jorgekafkazar

Peter Wilson says: “…But for Steig to claim he was publishing something “that appears to go against the grain” is just silly. The whole reason he got the attention he did, and so obviously craved, was that his work went very much WITH the grain, adding yet another continent to the global warming cause.”
Not just another continent. According to climate models (and possibly correctly), in global warming, the polar areas would have the greatest warming. If Steig had successfully teased a significant warming signal out of Antarctic data, instead of merely smearing West Antarctica temperatures all around the pole, it would have been a major accomplishment. Unfortunately for him, “It is hard to make data where none exist.” (–K. Trenberth) Steig’s failure was just slightly less important than the collapse of Mann’s hockey stick. Note that iirc Steig never claimed huge amounts of warming in the Antarctic, just that there was a positive trend.

Mark T

Yes, jorge. His pet theory got slaughtered and he lept to its defense with a flurry of of his own character assassinations.
Pathetic.
Mark

SSam

Ya know… every time this Younger Dryas impactor and the “lack of evidence” issue comes up, I think of the Cape York meteorite(s) and the Willamette Meteorite.
Interesting estimated dates.
http://en.wikipedia.org/wiki/Willamette_Meteorite
http://en.wikipedia.org/wiki/Cape_York_meteorite
But… a comet is not an asteroid, or meteor… unless you strip out all the volatiles.

BravoZulu

“It seemed like such an elegant answer to an age-old mystery: the disappearance of what are arguably North America’s first people. ”
It wasn’t elegant at all. It was completely ridiculous. A comet large enough to have killed animals over thousands of miles and changed the climate for centuries would have left a huge mark even if it did strike glaciers. In geological time, that 13,000 years is nothing. I have seen the guy claiming to have found iron filing all over North America and saying that was proof of a great impact. They normally look for shocked quartz or iridium and not iron filings so I thought the guy was nuts. I have even heard of them looking for microscopic diamonds. It sounds like it was probably West that I heard and I didn’t believe a word of it. It was a loony theory to be that recent without an impact site.

Bill Illis

At some point, the Clovis culture developed the atlatl and the bow and arrow. These technological developments produced a much less risky hunting strategy than surrounding a large mega-animal and killing it with 6 foot long hand-held spears. The Colvis points naturally dissappeared as the technology spread across the US (and I would imagine this would have spread fairly rapidly once the benefits became apparent).
The Mega-Fauna went extinct when the climate changed and the large grassland/tundra environment dissappeared. The Mammoth ate grass. Because CO2 levels were so low during the ice ages, C4 grasses could out-compete all other types of vegetation and the non-glaciated parts of North America and Asia and Europe were a grass-herbivore paradise. When the ice melted and the CO2 outgassed from the Oceans and the rainfall increased, the trees and bushes grew back and the slow fertility/reproduction rate of the Mega-Fauna spelled their demise. There wasn’t enough people around at the time to kill off that many Mammoths and giant Buffalo and giant Elk. We took a few naturally but climate change did the majority of the work.
No impact events or climate scientists are required for this explanation.

DesertYote

Al Gored says:
May 17, 2011 at 4:03 pm
Well, since the first people in North America, like all the hunter-gatherers in Eurasia, had tame wolves (dogs), imagine the combined effect. Then add fire. This combination seems to be almost always overlooked.
###
It seems like everyone overlooks the North American Indian dogs, sad 🙁

Bob

Was Michael Mann a co-author of the paper?

William

In reply to:
“Hoser says:
May 17, 2011 at 1:39 pm
In Greenland ice cores, 10-Be levels rise again during the Younger Dryas to almost the same concentrations as during the Ice Age and then fall to current low levels when the Younger Dryas ended. So how did cosmic rays know about the Younger Dryas? Just coincidence?”
There is a geomagnetic excursion that coincides with the Younger Dryas abrupt cooling. During a geomagnetic excursion the geomagnetic field intensity drops by a factor of roughly 3 to 5 and the non-diopole component of the field becomes stronger. It is a reduction of the geomagnetic field intensity and abrupt change in the geomagnetic field intensity that causes the increase in GCR to strike the earth. It is the increase in GCR that caused the Younger Dryas abrupt cooling. 80% of the cooling occurred within 10 years. The cooling period lasted for almost 1500 years.
The geomagnetic field excursions are cyclic. The sun is causing the geomagnetic field excursions when the solar cycle restarts after the geomagnetic cycle is restarted.
The burn marks throughout the Northern Hemisphere that all coincide is observational evidence of the mechanism. There are other burn marks on the earth’s surface that have been dated to later period. Those burn marks are elliptical in shape with orientation along a North west axis and with evidence of restrike. (One burn mark on top of another.)
Carolina Bays. The Carolina Bays are a group of »500,000 highly elliptical and often overlapping depressions scattered throughout the Atlantic Coastal Plain from New Jersey to Alabama (see SI Fig. 7). They range from ≈50 m to ≈10 km in length (10) and are up to ≈15 m deep with their parallel long axes oriented predominately to the northwest. The Bays have poorly stratified, sandy, elevated rims (up to 7 m) that often are higher to the southeast. All of the Bay rims examined were found to have, throughout their entire 1.5- to 5-m sandy rims, a typical assemblage of YDB markers (magnetic grains, magnetic microspherules, Ir, charcoal, soot, glass-like carbon, nanodiamonds, carbon spherules, and fullerenes with 3He). …
http://www.pnas.org/content/104/41/16016/suppl/DC1#F7
http://adsabs.harvard.edu/abs/2004E%26PSL.219..377T
Geomagnetic moment variation and paleomagnetic excursions since 400 kyr BP: a stacked record from sedimentary sequences of the Portuguese margin
A paleomagnetic study was performed in clayey-carbonate sedimentary sequences deposited during the last 400 kyr on the Portuguese margin (Northeast Atlantic Ocean). Declination and inclination of the stable remanent magnetization present recurrent deviations from the mean geomagnetic field direction. The normalized intensity documents a series of relative paleointensity (RPI) lows recognized in other reference records. Three directional anomalies occurring during RPI lows chronologically correspond to the Laschamp excursion (42 kyr BP),the Blake event (115-122 kyr BP) and the Icelandic basin excursion (190 kyr BP). A fourth directional anomaly recorded at 290 kyr BP during another RPI low defines the ‘Portuguese margin excursion’. Four non-excursional RPI lows are recorded at the ages of the Jamaica/Pringle falls,Mamaku,Calabrian Ridge 1,and Levantine excursions. The RPI record is characterized by a periodicity of V100 kyr,paleointensity lows often coinciding with the end of interglacial stages. This record sets the basis of the construction of an authigenic 10Be/9Be record from the same sedimentary sequences [Carcaillet et al.,this issue].
The geomagnetic moment loss (30%) over the last two millennia deduced from archeomagnetic results (e.g. [38,39]) might foreshadow the next excursion for the end of our present interglacial, even though this loss started 2200 years ago from an exceptionally high geomagnetic moment value.
Spectral analyses of the RPI record reveal a dominant periodicity at 100 kyr,already reported by other studies (e.g. [41,59,60]). The RPI and Fig. 13. Power spectra computed with the Analyseries program [62] using the Blackman^Tukey (BT) (confidence intervalat 95% vP/P is comprised between 0.64 and 1.78) and the maximum entropy method (MEM). (a) N18O. (b) RPI. (c) Inclination. (d) Power spectra (thick line) and 95% confidence intervals obtained using the Multitaper method. (e) Cross-coherence and (f) phase diagram of N18O and RPI. The thick horizontal line is the 95% confidence limit for zero coherence; the circle indicates the lag (V68‡=18 kyr) between RPI and N18O for the 100 kyr period. 18O records also present a phase shift of 18 kyr: RPI lows often coincide with the end of interglacial or interstadial stages.

JimF

Want some cheese with that whine, Eric? What a puke! As a geologist, I want to see his credentials revoked.
To whomever was going on about 8 or 9 planets – that’s just a matter of definition, not some horrendous lie or terrible error. I’m perfectly happy for Pluto to be a planet, but if you don’t think it is, well, I’m ok with that, too. It’s arguable (preferably over cigars and a couple bottles of good bordeaux).

William

This is a link to a paper that discusses the Younger Dryas black mats that are located at 97 locations throughout the Northern Hemisphere in Europe, Asia, Canada, and the US.
The Younger Dryas is a cyclic cooling event. The paleoclimatic record shows evidence of warming followed by abrupt cooling.
http://www.pnas.org/content/105/18/6520.short
Younger Dryas ‘‘black mats’’ and the Rancholabrean termination in North America
Of the 97 geoarchaeological sites of this study that bridge the Pleistocene-Holocene transition (last deglaciation), approximately two thirds have a black organic-rich layer or ‘‘black mat’’ in the form of mollic paleosols, aquolls, diatomites, or algal mats with radiocarbon ages suggesting they are stratigraphic manifestations
of the Younger Dryas cooling episode 10,900 B.P. to 9,800 B.P. (radiocarbon years). This layer or mat covers the Clovis-age landscape or surface on which the last remnants of the terminal Pleistocene megafauna are recorded. Stratigraphically and chronologically the extinction appears to have been catastrophic, seemingly too sudden and extensive for either human predation or climate change to have been the primary cause. This sudden Rancholabrean termination at 10,900 _ 50 B.P. appears to have coincided with the sudden climatic switch from Allerød warming to Younger Dryas cooling.
Nothing in the Quaternary stratigraphic record is more impressive than the abruptness of megafaunal extinction near the end of the Pleistocene. If all remaining elements of Rancholabrean megafauna, other than bison, terminated at the end of the Allerød chronozone, as indicated stratigraphically by the Z2 contact, the exact time of the catastrophic event is not resolvable within 100 years by radiocarbon dating, although this will improve significantly with tree-ring calibration (4). Grayson and Meltzer (43, 44) argue that Pleistocene extinction was gradual with some elements dying out long before others. This may indeed be true for a number of taxa but for many forms there are still inadequate geochronological data to accurately determine the exact age of their extinction. The fact remains that the existence of mammoths, mastodons, horses, camels, dire wolves, American lions, short-faced bears, sloths, and tapirs terminated abruptly at the Allerød-Younger Dryas boundary.
Of the 97 geoarchaeological sites of this study that bridge the Pleistocene-Holocene transition (last deglaciation), approximately two thirds have a black organic-rich layer or ‘‘black mat’’ in the form of mollic paleosols, aquolls, diatomites, or algal mats with radiocarbon ages suggesting they are stratigraphic manifestations
of the Younger Dryas cooling episode 10,900 B.P. to 9,800 B.P. (radiocarbon years). This layer or mat covers the Clovis-age landscape or surface on which the last remnants of the terminal Pleistocene megafauna are recorded. Stratigraphically and chronologically the extinction appears to have been catastrophic, seemingly too sudden and extensive for either human predation or climate change to have been the primary cause. This sudden Rancholabrean termination at 10,900 _ 50 B.P. appears to have coincided with the sudden climatic switch from Allerød warming to Younger Dryas cooling.
http://cio.eldoc.ub.rug.nl/FILES/root/2000/QuatIntRenssen/2000QuatIntRenssen.pdf
Younger Dryas Abrupt Cooling Event
…we argue that this is indeed supported by three observations: (1) the abrupt and strong increase in residual 14C at the start of the Younger Dryas that seems to be too sharp to be caused by ocean circulation changes alone, (2) the Younger Dryas being part of an approx. 2500 year quasi-cycle also found in the 14C record that is supposedly of solar origin, (3) the registration of the Younger Dryas in geological records in the tropics and the mid-latitudes of the Southern Hemisphere.
The Younger Dryas (YD, 12.9}11.6 ka cal BP, Alley et al., 1993) was a cold event that interrupted the general warming trend during the last deglaciation. The YD was not unique, as it represents the last of a number of events during the Late Pleistocene, all characterised by rapid and intensive cooling in the North Atlantic region (e.g., Bond et al., 1993; Anderson, 1997).
Moreover, the YD seems to be part of a millennial-scale cycle of cool climatic events that extends into the Holocene (Denton and KarleHn, 1973; Harvey, 1980; Magny and Ru!aldi, 1995; O’Brien et al., 1995; Bond et al., 1997). Based on analysis of the 14C record from tree rings, Stuiver and Braziunas (1993) suggested that solar variability could be an important factor affecting climate variations during the Holocene (see also Magny, 1993, 1995a),

Harold Pierce Jr

Some hard coals contain more than 95% carbon and would be classified as mineral like diamond and graphite

A G Foster

The dire wolf coexisted with the megafauna for a million years, as did the ice ages. But within very few millennia of the arrival of humans most of the big species disappeared, one after another. With such easy prey human populations would have expanded rapidly, to the point that prey quickly went extinct. All it takes is a hunting strategy which is less lethal than the birthrate. Even if it were more lethal, the hunters would to turn to other game, and come back later, even centuries later, for the more dangerous ones.
The giant, giraffe like camels probably ate what other camelids ate–everything. Camelids thrived wherever they went, South America, Asia, Africa, and finally Australia (they evolved in North America). Everywhere but the American South West, where they were reintroduced in numbers too few to aggregate. Climate was not their nemesis, except for the bridges climate made for two legged predators.
And how likely was it that the bow and agriculture evolved independently in the New World? We know the Da Ne people were later arrivals. All these coincidences are about as likely as a comet or asteroid wiping out the Clovis hunters. Pacific islanders that made it to Hawaii and Easter Island must have arrived in America far earlier, with all their technology–not early enough to introduce the bow, but possibly agriculture.
And everywhere humans went the native species disappeared in mass. Dodos, elephant birds, marsupial sabretoothes, thylacines (eventually). The native American species were as doomed as were the Native Americans themselves when Columbus arrived. Any Polynesians making it across the Pacific would have had to contend with the native syphilis.
Enough of that, but if you want to talk about a real unscientific but universally held fallacy, talk about the dawk hawk stoop. –AGF

Al Gored

Bill Illis says:
May 17, 2011 at 6:53 pm
“At some point, the Clovis culture developed the atlatl and the bow and arrow. These technological developments produced a much less risky hunting strategy than surrounding a large mega-animal and killing it with 6 foot long hand-held spears.”
Bow and arrow is a very recent ivention, unknown in North America until about 5-6000 years ago when it first appeared in the Arctic. Not in southern North American until much later. Much too late for this discussion. But atlatls maybe.
“surrounding a large mega-animal and killing it with 6 foot long hand-held spears.”
As George Frison has demonstrated with fascimile Clovis spearpoints and spears on African elephants ( and indigenous people there demonstrated for eons) that is not how they usually killed them. Instead you throw the spear into their gut and wait, and patiently follow, until they are incapacitated or die. Could take days or even weeks. The reward was worth the wait. That’s how tiny Bushmen could kill huge elephants with little arrows, safely.
There was no concern for a quick ‘sportsmanlike’ kill. That’s modern thought. And those artist’s renditions of people swarming around mammoths are just that, artist’s renditions done for effect.

We’ve done this before, for people who are interested. http://wattsupwiththat.com/2010/09/30/no-evidence-for-clovis-comet-catastrophe-archaeologists-say/
I don’t know why it has to be a (1) comet/asteroid, period. What about a shower of smaller fragments? Over a period of a year or two. That also contain high concentrations of 10-be.

Adam Gallon

A cometary impact wouldn’t necessarily leave an impact crater, it’d likely be an airburst, like the Tunguska Event. If it did occur over an icecap area, then the ground surface below the ice wouldn’t show any sign of it. So, that part of the theory can withstand scientific challenge.