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John Mason at 05:31 AM on 22 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Indeed, Wili - there are many examples. If you back into a lamp-post at 15mph you get a depressing garage bill to fix the damage: if you go head-on into one at 50mph the chances of survival are minimal. What "A" and "B" are does not matter a jot: it's the speed of change. A 6C warmer world would in fact be quite nice for a number of reasons if it took us a few million years to arrive at that point, but doing it over a few centuries would, as we say here in Wales, knacker us up badly!
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Theorist at 04:08 AM on 22 March 2015So what did-in the dinosaurs? A murder mystery…
The author of this article concludes that the Chicxulub impact was not the cause of the mass extinction. I agree. The author then concludes that the Deccan Traps must therefore be the cause.
I disagree.
Gerta Keller, who has studied the Deccan Traps extensively produced a chart displaying the three main Phases of eruptions of the Deccan Traps, which can be found at the following link:
http://www.princeton.edu/main/news/archive/S32/14/62G75/
The chart in the paper cited above is proof that neither the bolide impact nor the Deccan volcanism was the cause of the foram extinction:
PHASE 1 starting about 67.5 Mya and produced about 8% of the lava.
PHASE 2 starting about 65.3 Mya and produced about 80% of the lava.
PHASE 3 starting about 64.7 Mya and produced about 12% of the lava.
Each of the three Phases are sub-divided into 4 megaflows of lava.
As stated in the research paper and supporting the GTME is the following quote, which describes the foram extinctions:
"After studying microplankton remains in sediment from below, between and above the second-phase lava flows, the researchers observed that the number of living species dropped 50 percent at the onset of eruptions."Clearly, if this statement is accurate then neither the volcanic eruptions nor the bolide impact could have caused these extinctions. They occurred much too early for the negative environmental effects (specifically sulfur dioxide emissions and carbon dioxide) to have had an effect on forams.
The paper also states:
"The species count plunged by another 50 percent after the first of what would be four lava mega-flows."
This refers to PHASE 2.This indicates that about 75% of the forams became extinct by the end of the first megaflow within PHASE 2. And, by the end of the fourth megaflow the extinction was complete, which is when the bolide impact occurred.
If neither the bolide impact nor the Deccan volcanism caused the extinctions then what did?
Moderator Response:[PS] "the author then concludes that the Deccan Traps must therefore be the cause." Actually he puts forward an alternative scientifically plausible explanation. If you wanted to discuss "GTME", then you need peer-reviewed paper supporting the physical plausibility.
This article was published on this site because it has some relevance to possibilities inherent in rapid climate change. No further offtopic discussion of wild alternatives will be tolerated. Find another forum.
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Timothy Chase at 02:32 AM on 22 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
The article you reference is open access:
Bond, David PG, and Paul B. Wignall. "Large igneous provinces and mass extinctions: an update." Geological Society of America Special Papers 505 (2014): SPE505-02.
http://specialpapers.gsapubs.org/content/505/29It is part of a special collection:
Keller, Gerta, and Andrew C. Kerr. Volcanism, Impacts, and Mass Extinctions: Causes and Effects. Vol. 505. Geological Society of America, 2014.
http://specialpapers.gsapubs.org/online-first/505... which has a total of 24 articles, three others being open access:
Font, Eric, et al. "Atmospheric halogen and acid rains during the main phase of Deccan eruptions: Magnetic and mineral evidence." Geological Society of America Special Papers 505 (2014): SPE505-18.
Self, S., A. Schmidt, and T. A. Mather. "Emplacement characteristics, time scales, and volcanic gas release rates of continental flood basalt eruptions on Earth." Geological Society of America Special Papers 505 (2014): SPE505-16.
Miller, Steve. "The public impact of impacts: How the media play in the mass extinction debates." Geological Society of America Special Papers 505 (2014): 439-455.
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wili at 22:26 PM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Good points, JM. If you take a small piece of metal and move it at a snail's pace toward someone's head, they are not likely to feel threatened by it in the least.
Take the same small piece of metal and shoot it out of a gun at the same person's head and they are instantly dead.
The only difference between the two scenarios is rate of change.
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John Mason at 21:53 PM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Chris - IMO it is not the totality of the change but the rate of change from A to B that is so dangerous. Consider:on a repeated basis over the past 2.55 million years there have been transitions between glaciated and non-glaciated states, yet the rate of them has been sufficiently slow that no major mass-extinctions have resulted, despite the utterly transformative nature of such changes. If they took place over 500 years the outcome would likely be disastrous. The similarity between AGW and LIPs, and where they differ from Milankovitch-type fluctuations, is that the rate of change is much faster.
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chriskoz at 21:29 PM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
The outgased amount - 100,000GtCO2 (or my preferene 27,000GtC) is so enormous that it dwarfs any imaginable scale of AGW. The 2 degree warming target allows for 1000GtC only; we are just half way through it. Burning all available fosil fuels would release no more than 5000GtC, some 5-6 times less. Humanity is unable to match the scale of Siberian LIP excursion by burning FF no matter how hard it tries.
I agree will your math showing the rate of C release in AGW is comparable to that of siberian LIP, but those two events differ so much in magnitude that comparing their impacts seems almost incorrect. How can you justify such comparison? Is the difference in starting conditions (lower starting background CO2, brighter sun, polar ice caps) enough to justify the opinion that ongoing AGW event, bound to be at least 5-6 times smaller than said LIP event, can have the same consequences?
IMO, you should not ignore such difference in magnitude and simplify the equasion to the rate of C release only. To give an extreme example: the release of say 30MtC in one day (current rate AGW event) only and nothing more would be totally inconsequential and ignorable among natural variations. However, the same rate sustained for 100y results in AGW. The same rate sustained over 10,000y as in Siberian LIP results in more than AGW.
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Tom Curtis at 12:37 PM on 21 March 2015So what did-in the dinosaurs? A murder mystery…
Theorist @56, conservation of angular momentum only becomes relevant if the continents generates a significant mass anomaly. As seen above, they do not now and your assumption that they did in the era of Pangaea is entirely evidence free. I am not going to discuss this further. There is no point discussing pseudo-science with pseudo-scientists, and on the pseudo-science scale, yours is right up their with young earth creationism. Right down to the false, unevidenced claims that scientists do not have explanations for phenomenon which are well explained (or for which there are several scientific explanations between which evidence is insufficient to decide).
Moderator Response:[PS] Further discussion on these lines will be deemed offtopic and deleted.
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Watchdog at 12:24 PM on 21 March 2015So what did-in the dinosaurs? A murder mystery…
ranyl -
I'm placing the question of a chicxulub -> deccan traps connection, and Sulphur Trioxide and other gasses - including CO2 - on the side burner - for the sake of maintaining attention upon both events being self-evident causal factors of widespread catastrophic extinction of life.
What is it about their unquestionably individual catastrophic affects upon extinctions of life over millions of square miles of Earth, along with both of their acknowledged causings of known periods of inhospitable Global Freezing - that leads you to feel that they were not - at least - a very large part of the extinction of Dinosaurs?
I don't mind discussing CO2 and other Gasses, but not at the expense of what I perceive to be a possible glossing over the effects of: A) Chicxulub (and theorized additional meteroric impacts). B) Deccan Flats as well as both of the their accompanying C) - Global Freezing — - as if "CO2" somehow minimizes or supplants A, B & C. -
One Planet Only Forever at 09:08 AM on 21 March 20152015 SkS Weekly Digest #11
In addition to the 12 months ending in Feb 2015 being the warmest 12 months in the GISTEMP data set, the 6 months ending in Feb 2015 are also the warmest 6 months in the data set. The average for any other number of months more than 6 in the record also has the set ending in Feb 2015 as the warmest. And:
- The warmest 5 and 4 month sets were the ones ending in May 2010.
- The warmest 2 and 3 month sets were the ones ending in April 2010.
- And the warmest month was Jan 2007.
And the warm values ending in Feb 2015 have not been bumped by a significant El Nino event like the 2010 and 2007 values were bumped by.
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Theorist at 09:02 AM on 21 March 2015So what did-in the dinosaurs? A murder mystery…
@Andy Skuce .54 and Tom Curtis .55
As I stated in a prior posting, current gravity anomalies found around the globe are due to variations in crust/upper mantle densities, usually from compression by ice. These are minor and not related to core movement.
There is much evidence to support the GTME. If you viewed the Youtube video referenced earlier, you understand the basic concept:
When the continents, coalesced into larger masses, e.g., Pangea, and especially when that consolidated mass moved latitudinally, the law of conservation of angular momentum comes into play in the same way that it does when a spinning skater moves their outstretched arms close to the body or away from the body. In the case of the skater, their rotational velocity must change. For the Earth, when the coalesced mass moves latitudindally, the distance to the Earth’s axis changes in a comparable manner. Therefore, either the Earth’s rotational velocity changes or something else compensates to conserve angular momentum. GTME posits a movement of the core elements to compensate because there is no rotational change known. The movement of the core elements creates a gravitational gradient around the Earth.
Based on the above, some of the results are:
1. Terrestrial and marine life exhibited a much wider range in physical size than is possible today when the core elements moved away from Earth-centricity.
2. When the core elements moved rapidly toward Earth-centricity, surface gravity increased, flood basalt volcanism began and a massive drop in sea level occurred. The latitudinal movement is supported by a scientific study mentioned in the video which illustrates the latitudinal movement of Pangea over the last 300my.
3.When (2) above happens, methane is disassociated from the sea bottom because of the drop in sea level coupled with the (still) relatively low surface gravity. The volcanism further increases the disassociation because it raises the ocean temperature. In fact, the experts claim that the carbon isotope excursion at the P-T boundary was too large to be accounted for by the Siberian Traps alone.
4. At the Cretaceous-Triassic boundary, marsupials in N.America were almost completely wiped out in contrast to other small mammals.
http://phenomena.nationalgeographic.com/2014/12/24/the-opossums-tale/
This can be explained by a rapid increase in surface gravity. If you have an alternate explanation, I would be interested.
5. The reduction in size and complexity of the forams at the Cretaceous-Triassic transition can be explained by an increase in surface gravity, not only by a change in ocean chemistry. Smaller, less dense forams would be more buoyant and more likely survive if surface gravity increased.
Moderator Response:[PS] This discussion is now far offtopic and as far as I can see well away from the realms of peer-reviewed science. If proponents wish to continue this, then please find another forum. Further on-topic discussion can continue provided any assertion is first backed by peer-reviewed literature.
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Tom Curtis at 08:43 AM on 21 March 2015So what did-in the dinosaurs? A murder mystery…
Andy Skuce @54, agreed. If the GTME held any water (pun intended), there would be a consistent difference in the gravitational field such that continental areas has a stronger field than oceanic areas. That turns out not to be the case:
The strongest gravitational field, as it turns out, is not just (vaguely) near the North Pole, but along the mid oceanic ridge in the North Atlantic where active volcanism brings magma to the surface, with the second strongest being in the Indonesian archipelago.
Nor should this be a surprise. Continental crust floats on the asthenosphere, ie, the semi solid magma beneath the surface. Ergo it has a lower density and is, overall gravitationally neutral. Ergo the basic premise of GTME is false. We need not bother to follow through to its (sometimes very bizarre) conclusions to know the theory fails.
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Andy Skuce at 06:16 AM on 21 March 2015So what did-in the dinosaurs? A murder mystery…
I urge everyone here not to take the "Gravity Theory of Mass Extinctions" or GTME seriously at all. It is physically impossible and is completely unsupported by any peer-reviewed research.
If you are curious to know more read this, but please bear in mind that it is bunk.
There are indeed small gravity variations on the present Earth, due principally to the planet's rotation and changes in altitude of the surface. This means that the lowest gravity on Earth is to be found at the summit of Huarascan in Peru and the lowest near the North Pole. These differences are approximately 0.7%.
In other words, an average man weighing 80 kg, standing at the North Pole, would be about 600 grams heavier than the same guy perched on top of a peak in the Andes. If the chap at the pole emptied his bladder, they would then be about the same weight.
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howardlee at 06:05 AM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
L. Hamilton @ 2 - I made a point of attending as many of the sessions concerning plumes vs no plumes as I could. The geochemistry of plume-related magmas does argue for a base-mantle source and the fact that plumes have been imaged down to the D'' layer seems a clincher to me. Plus if you have residue of subducted slabs sinking down to the teepest mantle (as a number of studies have imaged) you must, as even Don Anderson agreed, have a compensating mass movement upwards. Agreed, plumes may not be universally accepted, but they are increasingly the consensus and about as accepted today as Plate Tectonics was in the mid 1970s.
Did you catch Barbara Romanowicz's AGU presentation "Of Mantle Plumes, Their Existence, and Their Nature: Insights from Whole Mantle SEM-Based Seismic Waveform Tomography"? Some clear imagery of ~400km wide plumes extending from the CMB there.
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howardlee at 05:47 AM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Interesting related paper just came to my attention today in Geology by Lindstrom et al, concering the Central Atlantic Magmatic Province (CAMP) associated with the end-Triassic Mass extinction. They say:
"magmatic intrusions into sedimentary strata during early stages of CAMP formation caused emission of gases (SO2, halocarbons, polycyclic aromatic hydrocarbons) that may have played a major part in the biotic crisis"
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howardlee at 05:41 AM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Chris Geo - I have just received a copy of "Volcanism and Global Environmental Change" by Schmidt, Fristad, and Elkins-Tanton (Cambridge University Press). As a genuine geologist you will find this interesting - and it goes into further detail about the topics John Mason has written about, with chapters from 53 eminent scientists including a number of genuine geologists.
You may also enjoy Geological Society of America Special Paper 505, by a bunch more geologists, which you will find entirely consistent with this post.
I have spent the last few years following the research on LIPs and global climate change and I also connsider myself a genuine geologist. Many of us geologists were educated some time ago with the idea that LIPs were slow-burn phenomena, but the latest high-resolution dating shows us they were far more rapid than thought. Lake all scientists we must follow the data, even if they overturn old ideas.
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ranyl at 04:53 AM on 21 March 2015So what did-in the dinosaurs? A murder mystery…
"Sediments drilled from within the Chicxulub crater itself tell a remarkably similar story to that at Boltysh. Once thought to be the settlings from the immediate aftermath of the impact and tsunami, they have since been shown to include a regular marine limestone containing the distinct late-Cretaceous CF1 fossils - so the crater must have been formed before the end-Cretaceous mass extinction! Corroborating that, rocks from Texas and Mexico show that the impact fallout (in the form of the oldest layer of impact spherules) predates the mass extinction by more than 100,000 years"
100,000years seems a long while really to be premature by.
"Deccan eruptions - for the Cretaceous global warming, ocean acidification, and extinction in the marine realm: guilty! For the terrestrial extinction including the dinosaurs: also guilty – but some may still claim reasonable doubt.
Chicxulub impact – for the Cretaceous global warming, ocean acidification, and extinction in the marine realm: not guilty! For the terrestrial extinction and doing-in the dinos: not guilty - It has an alibi, and there’s insufficient evidence of its ability to kill on a global scale to prosecute. After 30 years it’s time to let this one go. It has done its time."
Well drawn conclusions.
And if the bullet did start the eruption, still the CO2 heating and acidificatiom that are the murder weapons found present at the scene of the crime, rather than a historical impact which clearly caused major issues just not the extinction of the dinosaurs.
Given the evidence as well as that from other mass extinctions it seems a sudden release of CO2 can change climatic zones and transforms oceans rapidly enough for the global ecosystem to essentially reset itself to the new conditions, that is why there is always a boom after the bust; sometines after such a huge event it goes bbust, boom, bust, boom until it resettles in a more stable state again.
Watchdog,
As howardlee's research is extensive and the evidence convinving,
What is it about CO2 being the primary murder weapon that makes you feel that this possibility is in error?
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One Planet Only Forever at 04:47 AM on 21 March 2015Fossil fuels are way more expensive than you think
alby,
I agree with your clarification about what can be continued, but would further clarify that since this planet is expected to be habitable for several hundred million more years, any activity that can be continued for 100 years or even 1000 years is essentially pointless, unless the benefit created from that short burst of unsustainable activity will continue to be a benefit for everyone for a few hundred million years.
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John Mason at 03:34 AM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
I can certainly state a BSc, M.Phil, time spent in the minerals industry, a number of papers and involvement in more than one book. Plus a penchant for - if I am going to write about a topic - obtaining the latest peer-reviewed research. So come on Chris, whoever you are. Speak up!
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John Mason at 03:31 AM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Indeed - BGS have been using them for years - but portable zircon-dating units are still Star Trek! A lot of legwork is involved to do this type of dating.
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michael sweet at 02:48 AM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Chris:
You are arguing from authority but we do not know who you are. Can you provide some information about your background and degree in geology? BA, MS or PhD? What was your specialty? Have you published any papers about this era? Are you currently employed as a geologist? Can you provide evidence that your claims are true?
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Theorist at 02:34 AM on 21 March 2015So what did-in the dinosaurs? A murder mystery…
Watchdog,
Many people attribute the Deccan Traps volcanism to the Chicxulub impact. They view a current Earth map and erroneously assume that the near-antipodal relationship between the two locations existed 66 mya. I believe their logic is that the bolide impact traveled through the core(s) and disturbed the mantle/crust on the Indian sub-continent causing the eruptions. This could not have happened because the two locations were not antipodally positioned 66mya. I don’t believe there is any scientific evidence, based on the apparent latitudinal symmetry to the equator 66 mya, that this would be a feasible explanation.
Also, it is well known that the Deccan Traps began erupting long before the bolide impact occurred.
Returning to the question of whether flood basalt volcanism was responsible for prior mass extinctions, my belief is that the volcanism was the result of the core elements rapidly moving back toward Earth-centricity, and therefore were secondary causes of mass extinction, second to gravitational changes. It is interesting that there is little attention given to the cause of flood basalt volcanism. Specifically, why the greatest outpouring of flood basalt eruptions was greatest when all the continents were massed together and has diminished as the continents continued to separate. This aspect is readily explained by the GTME.
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The cause of the greatest mass-extinctions of all? Pollution (Part 2)
John Mason - Portable handheld X-ray fluorescence units are available right now. They aren't cheap, mind you, but they certainly can be had.
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witsend at 00:32 AM on 21 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
What about nitric acid being converted into tropospheric ozone, which is highly toxic to plants? Could that have played a role in mass extinctions where volcanic emissions are the initial event?
http://www.cee.mtu.edu/~reh/papers/pubs/non_Honrath/mather04a.pdf
Moderator Response:[JH] Link activated.
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alby at 23:22 PM on 20 March 2015Fossil fuels are way more expensive than you think
@O.P.O.F: I agree with your comment except for the point that the current technical-economic global system based on consumption of not-renewable resources cannot be continued. The very big problem is that cannot be for a long time (50 years or 100-150 years from now, difficult to say without crystal ball) but can be and it is happening in the real world, years after years without any significative change on the base path of mankind activities (using 15 Gtoe/year)
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DSL at 23:16 PM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Speaking as a member of the general public, Chris, I find your arguments less convincing than John's. Maybe it's the lack of evidence on your part.
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John Mason at 22:52 PM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Chris - start with the Bond & Wignall paper referenced here. Then read the numerous references cited below part two. We'll hear your piece in a few days after you have done that.
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Chris Geo at 22:40 PM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Speaking as a genuine geologist, this is a high school essay cut and pasted from somewhere, with a bunch of politicised carbon dioxide semi-truths jammed in every so often.
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DSL at 22:14 PM on 20 March 2015There is no consensus
Wakeup, it isn't beyond the capacity of scientists to explain, but you do have to do some of the work. They're not going to knock on your door. And you do have to learn, because the science gets complicated as we move away from the basics. It took ~850 scientists three years to summarize the existing science. They ended up with a 3000+ page report.
Moderator Response:[JH] wakeup's most recent comment constituted argumentative sloganeering and was therefore deleted.
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CBDunkerson at 21:50 PM on 20 March 2015There is no consensus
wakeup, so you've moved from 'there is no consensus!' to 'consensus does not matter!'? Should we anticipate that once all the evidence showing the effects of perceived expert consensus on public acceptance is presented you will move on to 'overwhelming agreement amongst experts does not make it true!' and then once all the evidence showing that AGW is true is presented (and denial of each fact countered) to 'all this evidence must be faked by the evil scientist conspiracy!'... or can we just skip to, 'Hey look, there is a complete database of information on this site which gives detailed rebuttals to every nonsensical claim you can come up with. Why don't you read those and get back to us if you find any which haven't already been proven false?'
As to civility, who was it that introduced themselves by throwing around phrases like, "This wouldn't be acceptable in a courtroom or a school science project", "volume of conflicting information", "fuzzy numbers", and "apparently authoritative statements that amount to gobbledegook"?
Moderator Response:[JH] wakeup's most recent comment constituted argumentative sloganeering and was therefore deleted.
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John Mason at 20:50 PM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Indeed - zircons are solving so many long-standing problems in stratigraphy. It's a bit Star-Trek but wouldn't it be nice if there was a bit of kit like portable XRF that you could use in the field - just place the probe against any rock and if it has zircons in it up come the data on the properties of them on the screen! Perhaps in 100 years....
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Alex Fiquerman at 19:51 PM on 20 March 2015Putting an End to the Myth that Renewable Energy is too Expensive
Indeed, a cheapskate pays twice, and it’s pretty reasonable in this case. Unfortunately, we keep on making it more expensive to preserve the world from complete environmental disaster by trying to save money using the resources we have very doubtful rights. I would like to comment on CBDunkerson who pointed out we all will be fine if we simply go with less CO2 in our everyday life and redistribute the energy from hazardous transportation to safe and clear means. I completely agree, that this is not only the matte of concern of environmentalists and governments, but of each of us. As soon as everyone focuses more on the health of the planet, we will manage it in a collective and effective way. And beware, the world’s plants, like China and India, can’t be responsible for all the pollution issues: it’s us who get obsessed with purchasing and consuming, it’s us who orders more plastic. If you want to make it cheap, try starting from yourselves. For example, when you decide to make your economic standing more stable, you don’t make it through spending more, you simply stop buying, you start saving and, probably, encourage more effective financial operations and address to professionals, like http://loansmob.com/ that can provide you with a viable source to correct your financial reputation. Exactly like that you contribute to the common goal of making environmental activity cheaper – you spend less and save more.
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Leto at 17:52 PM on 20 March 2015It's the sun
Hi Tom,
Points taken. My rhetorical example was admittedly unfar, as it would obviously be facile and unhelpful to suggest that a model was okay because only 1% of its errors were worse than the 99th centile of its errors. And although I would see it as almost as facile and circular to defend a model because "only" the expected number of its worst errors were beyond some number of SDs of its own error distribution, that is not quite the same as pointing out, as you did, that the most extreme outlier was only ~3.3 SDs worse than the mean errors. If the outliers were several SDs out, we both agree that would be an entirely different situation.
Thanks, and best wishes,
Leto.
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TonyW at 17:15 PM on 20 March 2015Crowdfunding Support for Science: The Dark Snow Project
Thanks, scaddenp, the caption makes it clear. It's a shame it was missing from this post.
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uncletimrob at 17:15 PM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Thanks John
again an article that takes me back to early undergraduate days when radio-dating was considered to be a very inexact science. In fact it was considered so ineaxact by creationists that the measurements were proof of creation. Thank you. Most infomative and another one to add to the "must read" list for my students.
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scaddenp at 16:30 PM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
William, I havent run a specific model on that but based on lots of models for "normal" heatflows, I dont think can get remotely get to melt temperature. If there is an effect, I think it is dwarfed by variations in heat flow from mantle convection.
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Watchdog at 13:43 PM on 20 March 2015So what did-in the dinosaurs? A murder mystery…
Apology for duplicate post. A view of the Earth-Globes from 65MYA and Today can give a better sense of continental separation than a flat map. Note how continental separation of 65MYA are not overly dissimilar to Today's continental separation. As Tom Curtis pointed out with respect to the angle of Chicxulub's impact, the Chicxulub & Deccan Traps events do not have to be axial through Earth's center.
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Tom Curtis at 13:39 PM on 20 March 2015So what did-in the dinosaurs? A murder mystery…
Watchdog @49, they were for the most part situated in one hemisphere delineated by longitude (ie, like the western hemisphere). Theorist is correct on that point, if a little obscure.
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ranyl at 13:20 PM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Thanks John good articles.
A few things to consider though.
Heating affect from CO2 is relative to starting value, thus we going much faster than in those days in terms heating in.
Also the presence of ice increases warming further by a factor of ~2 due to alebdo effects.
Further the sun was significanlty dimmer back then, meaning we should warm more quickly again as get more input from the sun all the radiaitve components follow suit.
And lastly even though SO2 not as high as then, all the other toxic stuff we've introduced in the way of biocides, heavy metals, toxic wastes and endocrine disruptors probably aren't helping matters.
Then of course there is the gross overexploitation of biosphere resources, the widespread destruction of habitats done directly by human hands and there is the biodiversity lethal aspects of wars which seem on th eup again recently all which again aren't helping.
And aren't the current extinction quite remarkeable in the geological record?
No wonder the hedgehog is even feeling it!
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Watchdog at 13:11 PM on 20 March 2015So what did-in the dinosaurs? A murder mystery…
Theorist
65 MYA, the continents were _Not_ positioned in one hemisphere.
Please note India's position 65MYA wrt the Chicxulub's Impact site.
http://www.lpl.arizona.edu/~hubbard/PtyS195a/Mar06/Fig2-5globes.gif
Moderator Response:[JH] Link activated.
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william5331 at 12:50 PM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Could it be that these gigantic outpourings of lava are a result of a bunch of continents coming together and forming an insullating layer on a big chunk of the earth's surface. Heat from radioactive sources builds and builds under these mega-continents until the melt is too much for the strength of the overlying, thick, continental rock. If this is so, one would expect such eruptions to occur around the middle of super continents and possibly lead to the splitting of the mega continent and the creation of a new ocean.
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ginckgo at 12:49 PM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
There's possibly even more to this event than just volcanic 'pollution', and it's even closer to the modern pollution scenario.
Just recently researchers have used genetic clocks to pinpoint the timing when a group of methanogenic bacteria first acquired this trait to produce methane - and it falls just about bang on the end Permian time.
Methanosarcina- Role in the Permian Triassic extinction event
It looks like the isotope patterns favour this source of atmospheric carbon, over the volcanic one. The Siberian Traps, however, may have been the source of important elements, like nickel, allowing for Methanosarcina to bloom massively.
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Tom Curtis at 12:36 PM on 20 March 2015So what did-in the dinosaurs? A murder mystery…
Theorist @45, here are the continental configurations at the time of the K/T boundary according to Scotese:
Based on that configuration, the Decan traps were as far south of the equator as the impact site was north of the equator, but 130 degrees of longitude west of the impact site, not 180 as require to be truly antipodal. That compares with the modern arangement where they have approximately the same latitude but are approximately 180 degrees of longitude apart. That means the divergence from the true antipodal point is about the same in both cases, having shifted from a divergence in longitude to a divergence in latitude. Presumably the divergence is accounted for by assuming the impactor came in at a low angle, thus causing the point of focus to be shifted from the true antipodal point.
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Tom Curtis at 12:21 PM on 20 March 2015It's the sun
Leto @1141, for comparison, I took HadCRUT4 from 1880-2010 and used it as a model to predict GISS LOTI. To do so, I used the full period as the anomaly period. Having done so, I compared statistics with the Cowtan model as a predictor of temperatures. The summary statistics are (HadCRUT4 first, Cowtan Model second):
Correl: 0.986, 0.965
R^2: 0.972, 0.932
RMSE: 0.047, 0.067
St Dev: 0.047, 0.067
Clearly HadCRUT4 is the better model, but given that both it and GISS LOTI purport to be direct estimates of the same thing, that is hardly surprising. What is important is that the differences in RMSE and St Deviations between the HadCRUT4 model and the Cowtan model are small. The Cowtan model, in other words, is not much inferior to an alternative approach at direct measurement in its accuracy. Using HadCRUT4 as a predictive model of GISS, we also have a high standard deviation "error" (-2.5 StDev in 1948) with other high errors clustering around it.
This comparison informs my attitude to the Cowtan model. If you have three temperature indices, and only with difficulty can pick out that which was based on a forcing model to those which were based on compilations of temperature records, we are ill advised to assume that any "error" in the model when compared with a particular temperature index represents an actual problem with the model rather than a chance divergence. (On which point, it should be noted that the RMSE between the Cowtan model and observations would have been reduced by about 0.03 if I had adjusted them to have a common mean as I did with the two temperature indices.) Especially given that divergences between temperature indices show similar patterns of persistence.
Now, turning to your specific points:
"The bigger problem I have with the "It's chance" line of argument is that it seems to be largely devoid of explanatory power."
In fact, saying "it's chance" amounts to saying that there is no explanation, so of course it is devoid of explanatory power. In this particular context, it amounts to saying that the explanation is not to be found in either error in the measurements (of temperatures, forcings, ENSO, etc) nor in the model. That leaves open that some other minor influence or group of influences on GMST (of which there are no doubt several) was responsible. "Was", not "may be" because it is a deterministic system. However, the factor responsible may be chaotic so that absent isolating it (very difficult among the many candidates with so small an effect) and providing an actual index of it over time, we cannot improve the model.
"Asking why a particular patch of data-model matching is much worse than the rest is more analagous to the second situation, I believe."
Of course it is more analogous to the second situation. But the point is that the "it's chance" 'explanation' has a better than 5% (but less than 50%) chance of being right. That is, there is a significant chance that the model cannot be improved, or can only be improved by including some as yet unknown forcing or regional climate variation. The alternative to the "it's chance" 'explanation" is that the model can be improved by improving temperature, ENSO or forcing records to the point where it eliminates such discrepancies as found in the 1940s. On current evidence, odds on this is the case - but it is not an open and shut case that it is so.
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Theorist at 11:11 AM on 20 March 2015So what did-in the dinosaurs? A murder mystery…
Watchdog,
A better map can be found at www.scotese.com. Select "Earth History" and then "K-T Extinction" and you will see that the continents occupied close to one hemisphere. Also note the relative positions of Chicxulub and India.
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Watchdog at 10:29 AM on 20 March 2015So what did-in the dinosaurs? A murder mystery…
Theorist
65 MYA, the continents were _Not_ positioned in one hemisphere.
Please note India's position 65MYA wrt the Chicxulub's Impact site.
http://www.lpl.arizona.edu/~hubbard/PtyS195a/Mar06/Fig2-5globes.gifModerator Response:[PS] Fixed link.
Creating a link isnt hard people. If you want people to see it, please do it as you make comment. -
Theorist at 10:00 AM on 20 March 2015So what did-in the dinosaurs? A murder mystery…
Watchdog @44
Regarding your comments:
Point 1- At the time of the bolide impact, Chicxulub was not anti-podal to the Deccan Traps. All of the continents were still positioned on one hemisphere of the Earth.
Points 2 and 3 -Chicxulub and the Deccan Traps did have a profound effect on the Earth’s temperature. I’m not aware of any glaciation at that time. I wouldn’t conclude there was glaciation because of the drop in sea level because the theory I mentioned, I’ll call it the GTME, explains that when the Earth’s core elements move back toward Earth-centricity and surface gravity increases, sea levels near Pangea’s continental remnants must have lowered, as they did. The same type of massive sea level drop occurred at the P-T boundary for, I believe, the same reason it did at the Cretaceous-Triassic boundary. And, I’m not aware of any glaciation at that time.
The gravity anomolies that you refer to in Canada and elsewhere are caused by crust compression from overlaying ice. This is far different and significantly smaller than those caused by the movement of the Earth’s core elements theorized by the GTME.
Regarding your final statement about the dinosaur extinction, my belief, based on their gradual extinction throughout the Cretaceous and the rapid disappearance of the remaining dinosaur taxa at the very end, cannot be explained by the bolide impact nor the volcanic theories or by attributing the extinctions to their combined effects. Dinosaur fossils have been found near the Deccan Traps between major lava flows raising doubt whether worldwide extinctions could have been the result of volcanism.
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L. Hamilton at 09:55 AM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
And props too for accurately including this caveat, usually skipped in popular geology:
That there is still much lively (and at times acrimonious) debate concerning the Plumes Hypothesis, including postulated alternative formation-mechanisms for LIPs, need not concern us here.
There is indeed a lively debate, including many recent papers (and presentations at last year's AGU) arguing that contrary to every textbook, deep-mantle plumes do not exist. Some of that work is cited in this more colorful piece describing the plume hypothesis as "zombie science."
http://www.mantleplumes.org/Zombie.html
Moderator Response:[PS] Fixed link
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mav1234 at 08:37 AM on 20 March 2015There is no consensus
wakeup @666: This survey is not the only evidence used "daily" to suggest an overwhelming consensus among climate scientists, and in fact, it references several other studies that support that position. I agree there are limitations of this study (hence my question), but the consensus is pretty clear from other sources as well.
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vrooomie at 08:36 AM on 20 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Speaking as a geologist, this is a very well-written and readable account. Kudos to you for assembling it all in such an easily-understood essay.
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mav1234 at 08:35 AM on 20 March 2015There is no consensus
michael sweet @664: Please re-read Cook et al and check the author survey sent - inconclusive was not a choice given to the authors of papers. I believe it is clear from the methods and the nature of the subset of abstracts receiving a treatment of inconclusive that Cooke et al realized their error late in the process and thus were unable to completely correct for this. I do not doubt that the number of scientists publishing papers indicating they are unconvinced is very low, but I was hoping someone was aware of such a study.
I am trying to find if anyone has quantified this in any way, that was all. I am not attempting to dismiss the consensus on AGW.
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