About 12,800 years ago, the last Ice Age was coming to an end, the planet was warming up. Then, inexplicably, the planet plunged into a deep freeze, returning to near-glacial temperatures for more than a millennium before getting warm again. The mammoths disappeared at about the same time, as did some Native American cultures that thrived on hunting them. That climatic event is known as The Younger Dryas.
Many explanations for the event point to the impact of a comet or an asteroid, but now there is a new study suggests the driver/trigger was all from terrestrial based events.”
According to the article in Science Magazine, they find no evidence for an impact:
The study “pulls the rug out from under the contrived impact hypothesis quite nicely,” says Christian Koeberl, a geochemist at the University of Vienna. Most evidence for the extraterrestrial impact hypothesis, he says, was conjured up “out of thin air.”
The notion was popularized in television documentaries and other coverage on the National Geographic Channel, History Channel, and the PBS program NOVA.
…
Now comes what some researchers consider the strongest attack yet on the Younger Dryas impact hypothesis. In a paper published online this week in the Proceedings of the National Academy of Sciences, a team led by David Meltzer, an archaeologist at Southern Methodist University, Dallas, in Texas, looks at the dating of 29 different sites in the Americas, Europe, and the Middle East in which impact advocates have reported evidence for a cosmic collision.
Only three of the 29 sites actually fall within the time frame of the Younger Dryas onset
http://news.sciencemag.org/archaeology/2014/05/what-caused-1300-year-deep-freeze
From the publication:
A key element underpinning the controversial hypothesis of a widely destructive extraterrestrial impact at the onset of the Younger Dryas is the claim that 29 sites across four continents yield impact indicators all dated to 12,800 ± 150 years ago. This claim can be rejected: only three of those sites are dated to this window of time. At the remainder, the supposed impact markers are undated or significantly older or younger than 12,800 years ago. Either there were many more impacts than supposed, including one as recently as 5 centuries ago, or, far more likely, these are not extraterrestrial impact markers.
Chronological evidence fails to support claim of an isochronous widespread layer of cosmic impact indicators dated to 12,800 years ago
David J. Meltzer, doi: 10.1073/pnas.1401150111
David J. Meltzera, Vance T. Holliday, Michael D. Cannon, and D. Shane Miller
Abstract
According to the Younger Dryas Impact Hypothesis (YDIH), ∼12,800 calendar years before present, North America experienced an extraterrestrial impact that triggered the Younger Dryas and devastated human populations and biotic communities on this continent and elsewhere. This supposed event is reportedly marked by multiple impact indicators, but critics have challenged this evidence, and considerable controversy now surrounds the YDIH. Proponents of the YDIH state that a key test of the hypothesis is whether those indicators are isochronous and securely dated to the Younger Dryas onset. They are not. We have examined the age basis of the supposed Younger Dryas boundary layer at the 29 sites and regions in North and South America, Europe, and the Middle East in which proponents report its occurrence. Several of the sites lack any age control, others have radiometric ages that are chronologically irrelevant, nearly a dozen have ages inferred by statistically and chronologically flawed age–depth interpolations, and in several the ages directly on the supposed impact layer are older or younger than ∼12,800 calendar years ago. Only 3 of the 29 sites fall within the temporal window of the YD onset as defined by YDIH proponents. The YDIH fails the critical chronological test of an isochronous event at the YD onset, which, coupled with the many published concerns about the extraterrestrial origin of the purported impact markers, renders the YDIH unsupported. There is no reason or compelling evidence to accept the claim that a cosmic impact occurred ∼12,800 y ago and caused the Younger Dryas.
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MWP and LIA annotations can’t be right in the picture?
In a paper published online this week in the Proceedings of the National Academy of Sciences, a team led by David Meltzer.
Appropriate for a paper about the end of an ice age.
I don’t see any alternative suggestion for the cause being mentioned .
Everyone knows the mammoths were driving SUVs and caused their own extinction
They were mammoths, they made mammoth farts…
[SNIP electric universe bullshit has no place here – Anthony]
I go with the mammoth fart theory. It explains everything.
The 3 million years of the Earth’s history has 30 or so glaciation epochs each about 100,000 years, inter-spaced with about 10,000 years of warm epochs between them.
Our 10K years is up.
In geological terms it appears that climate is a bi-stable affair, and those familiar with the bi-stable oscillators will know that once you approach critical period even a small input excitation will tip it over into the alternative state.
If the AGWs are correct, then the northern latitudes civilization’s only hope is to pump as much CO2 as possible and at same time build as many as possible nuclear power stations, might need one for each major city.
AGWs keep telling us “it is worse than expected”, but even they do not realize how much worse may get.
It was the cavemen. They heeded all the warnings about “global warming” and put their campfires out.
The geomagnetic field changes and heliospheric field changes are correlate with abrupt drops in planetary temperature and great vulcanic eruptions.
http://michelecasati.altervista.org/index.html
It wasn’t an impact(s) so what was it? What are the conclusions? If any. If not this is not a proper science research paper.
The AR4 didn’t mention any impact theory 6.4-2-2:
“Freshwater influx is the likely cause for the cold events at the end of the last ice age (i.e., the Younger Dryas and the 8.2 ka event). Rather than sliding ice, it is the inflow of melt water from melting ice due to the climatic warming at this time that could have interfered with the MOC and heat transport in the Atlantic – a discharge into the Arctic Ocean of the order 0.1 Sv may have triggered the Younger Dryas (Tarasov and Peltier, 2005), while the 8.2 ka event was probably linked to one or more floods equal to 11 to 42 cm of sea level rise within a few years (Clarke et al., 2004; see Section 6.5.2).”
I don’t have a subscription to PNAS so I can’t read the paper, but, my question is:
If they found that three impact sites did fall in the chronological time frame, did they examine those sites to determine if the impact could have been big enough to spark the Younger Dryas temp drop?
what caused the rapid warming?
take that away and you get the rapid cooling.
From the Guardian (BBC will publish it online later):
‘Scientists believe they have found the cause of a cooling period 13,000 years ago. Excavating in a secret location, scientists think they have come across an early hybrid farm vehicle. Professor Ed Case says that the vehicle had an Ox front but clearly had a piston-engined rear drive. “We believe that vehicles of this type clearly were the cause, as they would have emitted large amounts of soot due to a lack of understanding about catalytic converters.” Professor Case told the Guardian that it was Man what was to blame. “It surely was.” said Professor Case. A new BBC series showing the excavations and these remarkable vehicles is planned.’
http://humanpast.net/images/preshistory0001.jpg
[/sarchasm That gaping whole between reality and the CAGW religion .. Mod]
Mammoth farts is a possibility, but I bet those bad ol’ Neanderthals caused it by burning tons upon tons of mammoth chips.
Mr Stokes,
Doesn’t seem like the IPCC was all that certain about the ‘freshwater influx’ hypothesis. Do they present any evidence to support what appears to be conjectural ‘floods’ and ‘fresh water influx’?
Nick Stokes says:
May 13, 2014 at 4:25 am
a discharge into the Arctic Ocean of the order 0.1 Sv may have triggered the Younger Dryas (AR4).
……
Are you sure about that?
Arctic overflow is about 10Sv, so AGW caused melting of the Greenland glaciers with another excessive Arctic ice melt, may produce the required 0.1 Sv of fresh water, creating a tipping point into a new Ice Age.
I’m telling you all, if we upload enough of these nonsense articles, Google will pick them up and they’ll get stored as genuine Guardian articles that are every bit as absurd as their general stuff! Write your own right now.
There are huge problems with all the theories about the YD cooling. Mamoths have been found frozen with their last meal well preserved in their stomachs. This can only happen when freezing is extremely fast. In our current climate there is nowhere on earth, where vegetarian animals live, where this fast freeze can happen. The temperature drop must have been massive and very fast. Remember, bodies decompose from the inside out !!
If you study all of the records at the Younger Dryas boundary, there is certainly a lot more to say to it. It may or may not have been one or more impactor. One of these records for instance is the so called radiocarbon reservoir age in the ocean. For ust about every period this is well controlled and understood except for the beginning of the Younger Dryas. See Reimer et al 2009. (Radiocarbon, Vol 51, Nr 4, 2009, p 1111–1150) Why would that be? It could point to extreme overturning of the ocean layers. Can that be attributed to impactors?
Nick Stokes…in quoting AR4 and my paraphrasing……
The warming caused all of that cooling!!!!
WOW
My understanding is that there was no precipitous drop in atmospherics CO2 concentrations prior to the Younger Dryas. I believe CO2 concentrations continued to rise throughout the YD event.
Steven said:
There are huge problems with all the theories about the YD cooling.
No there are no mammoth mummies dated to the Younger Dryas. Most are much older. It’s a totally different story. It would pay to read the real scientific literature about this. Not the sensational fairy tales.
Recommended:
http://epic.awi.de/9052/1/Hub2004a.pdf
http://cio.eldoc.ub.rug.nl/FILES/root/2006/QuatIntMol2/2006QuatIntMol2.pdf?q=jarkov
Read that first, before believing anything about the ‘flash frozen’ tales.
Did no one else think it strange that, according to the labelling on the headline graph, present day global warming appears to be colder than the little ice age?
The labelling is misleading and. in my opinion, this sort of thing undermines sceptic credibility.
The graph seems to be derived from the GISP2 ice core (Richard Alley Quaternary Science Reviews Volume 19, Issues 1-5, 1 January 2000, Pages 213-226).
The GISP ice-core records do not go up to the present time. They estimate up to about 100 years ago and so do not include ‘present global warming’. What is labelled as ‘present global warming’ is in fact the ‘little ice age’. Also note that the labelling of medieval warm period is incorrect. It should be the final little blip coloured red on the upslope.
You can see the original here (before Mr. Easterbrook got at it)
http://www.ncdc.noaa.gov/paleo/pubs/alley2000/alley2000.html
The graph by Easterbrook shows MWP warmer than present. What was the source of his graph and how widely accepted is it?