Sudden Clovis climate death by comet – "bogus"

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.

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.

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),

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