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scpg02
Joined: 22 Jul 2007
Posts: 221
Location: Sacramento
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 Posted: Tue Sep 25, 2007 2:54 am Post subject: Research team says extraterrestrial impact to blame for Ice |
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Contact: Lisa Nelson
Lisa.Nelson@nau.edu
928-523-6123
Northern Arizona University
Research team says extraterrestrial impact to blame for Ice Age extinctions
| Quote: | What caused the extinction of mammoths and the decline of Stone Age people about 13,000 years ago remains hotly debated. Overhunting by Paleoindians, climate change and disease lead the list of probable causes. But an idea once considered a little out there is now hitting closer to home.
A team of international researchers, including two Northern Arizona University geologists, reports evidence that a comet or low-density object barreling toward Earth exploded in the upper atmosphere and triggered a devastating swath of destruction that wiped out most of the large animals, their habitat and humans of that period.
“The detonation either fried them or compressed them because of the shock wave,” said Ted Bunch, NAU adjunct professor of geology and former NASA researcher who specializes in impact craters. “It was a mini nuclear winter.” |
http://www.eurekalert.org/pub_releases/2007-09/nau-rts092407.php
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Baywax
Joined: 23 Jul 2007
Posts: 113
Location: Pacific West Coast
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| Posted: Tue Sep 25, 2007 11:34 pm Post subject: |
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None of the remains found to date have been "fried" or "compressed". This report uses the outdated term "paleoindians"... are they from India?!!! How reliable is this?
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Andre
Joined: 21 Jul 2007
Posts: 298
Location: Germany - The Nederlands
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| Posted: Sun Sep 30, 2007 5:25 pm Post subject: |
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Thanks Maggie,
we knew that one for some time and it's a fine example how much BS science can generate. it's incredible:
| Quote: | | The detonation either fried them or compressed them because of the shock wave,” said Ted Bunch, NAU adjunct professor of geology and former NASA researcher who specializes in impact craters. “It was a mini nuclear winter.” |
While I have no objection against cosmic events, there arre sooooo many things wrong.
1. Such a large event such a short time ago would have left an impact crater which would be still todays main feature on the surface of the planet. Okay there are the Carolina bays but by what mechanism?
2. An impact causing nuclear winter would have left an uniform tephra like layer on a large part of the northern hemisphere. But it's not there.
3. The mega extinction was a gradual process, which started ~18,000 calendar years years ago, had major accellerations around 14,500 calendar years ago (Europe), 12,700 Calendar years ago in America (the claimed meteorite), 11,400 calendar years ago in Siberia. All can be tied to sudden arid-moist changes. Why would we need a cosmic event to explain a part of it.
4. The meteorite is assumed to have hit 12,900 years ago, causing the Younger Dryas. No check the YD exhibits. The YD was supposed to have started 12,670 years ago. 12,900 was the start of the last Allerod spike, which was eroneously supposed to be a warming event.
5. All the proxies (oceanic, ice cores isotopes, deuterium excess and methane) do show similar features not only for the Younger Dryas but also for all periods between the two dozen Dansgaard Oeschger events the last 100,000 years ago. Highly suggesting that those were all similar in nature, which begs the question where all those meteoritie impacts are.
A meteorite, fine, no problem, but it had nothing to do with extinctions or nuclear winters.
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John L
Joined: 03 Nov 2007
Posts: 21
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| Posted: Sat Nov 03, 2007 4:42 am Post subject: |
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Even if the object had vaporized in the atmosphere, it would have only caused such destruction in a limited area, such as the Tunguska event. Prehistoric large fauna were spread out all over the northern portions of Europe, Siberia and North America.
It could have been a combination of causes, but man would be at the top of the list, IMO. |
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Andre
Joined: 21 Jul 2007
Posts: 298
Location: Germany - The Nederlands
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| Posted: Sat Nov 03, 2007 2:35 pm Post subject: |
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Hi John and welcome
About the impact, well there is some evidence worth while investigating, but not the Younger Dryas and the extinction. Anyway, some good discussions about the latter for a change here:
http://www.realclimate.org/index....ives/2007/10/younger-dry-as-dust/
My response #70 "awaits moderation" So I'm not sure if you can see it:
| Quote: | Gavin,
Regardless of the validity of the 15N 40Ar method in Greenland, isn’t the long-term temperature gradient of d18O in meteoric water about 0.6 mil/oC (Rozanski et al., 1993)? This is easily verifiable with the GNIP database, showing the same general seasonal gradient on moderate latitudes. So, the ~4 mil jumps during the different glacial termination intervals would represent temperature changes of about 6-7 degrees in the lacustrine records of the different mid latitude lakes in Europe like the Gerzensee (Schwander et al 2000), Ammersee (Von Grafenstein 2002), etc. Yet the biota abundance proxies suggest no more than 2 degrees variation. Wouldn’t the difference exceed normal expectations?
Re #68 Steve,
Considering the Swiss multiproxy studies, you may like to recheck for instance Brooks 2000 (PPP-159, 261-279) and Lotter et al 2000 (PPP-159, 349-361) to see them struggling with unusual, contradictory responses of several taxa to the inferred temperature changes. If the several proxies don’t add up, the ad hoc hypotheses, are merely just that, severely degrading the main hypothesis of sudden and extreme cooling during the Younger Dryas. You might just as well test the observations of a Bjorck et al 2002 scenario, featuring high aridity, and as a consequence warmer summers and colder winters, aggravated by the approaching northern hemisphere summer insolation maximum.
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