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Nuclear war destroying the planet? Nukes vs Dino-Comet

  1. Jan 28, 2017 #1
    There are approximately 15 000 nuclear weapons on the planet. The largest one as far as I am aware is the Tsar Bomba, which packs a punch of (rounding here) 100 megatons of TNT.

    So if all of them were Tsar Bombas, we'd be looking at 15 000*100 megatons TNT = 1 500 000 000 000 tons TNT. Source: https://en.wikipedia.org/wiki/Tsar_Bomba

    Meanwhile, the comet that killed the dinosaurs is estimated to have had a 100 trillion ton TNT equivalence. Source: http://scienceline.ucsb.edu/getkey.php?key=2200

    So if 100 trillion tons TNT equivalence didn't destroy the planet, how is one trillion, five hundred billion? It's two orders of magnitude less, yet it's supposed to destroy the planet three times over? How?


    I'm not saying it might not destroy all of human society. I mean, one per major human city could certainly do that. And I'm not saying there wouldn't be massive repercussions down the line (nuclear winter, etc). But surely the Big One that destroyed the dinosaurs and countless other creatures had similar long lasting effects? So how are nuclear weapons capable of destroying the planet when the Dino-killing Big One, which was two orders of magnitude more powerful, was not?
     
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  3. Jan 28, 2017 #2

    Bandersnatch

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    Who says they are? By 'destroying' do these people mean the same thing you mean?
     
  4. Jan 28, 2017 #3

    ZapperZ

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    Who is making such a claim, other than you?

    Zz.
     
  5. Jan 28, 2017 #4
    I do not know. I see the phrase a lot in blogs discussing nuclear war. I can only guess that the people making the claim are repeating something told to them and misinterpreting it. Usually there are no qualifications distinguishing between destroying modern human civilization and destroying the planet in these blogs.
     
  6. Jan 28, 2017 #5

    ZapperZ

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    So why are you wasting effort in trying to debunk unsupported nonsense you see on "blogs"?

    Zz.
     
  7. Jan 28, 2017 #6
    Bloggers, youtubers, etc. Not scientists. For example:

     
  8. Jan 28, 2017 #7
    I'm not. Haha. If I wanted to do that I wouldn't be posting it on a physics forum. I'm trying to see what experts think of the matter, and whether I'm off base on assuming that the world would survive, even if modern human society would not.

    But I have quickly been chastened in my foolishness in not consulting the experts first. The bottom line is this issue has confused me recently. I've read in so many places that humans could destroy Earth with nuclear war, but then I keep thinking of the mass extinction events from which Earth has resiliently survived, and it brings confusion.


    *NOTE- I in no way endorse nuclear war ;). This is not a political question, even if this topic is often politicized.
     
  9. Jan 28, 2017 #8

    Bandersnatch

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    Well then, then what is there to discuss? It's obviously not enough to unbind Earth (by many, many orders of magnitude), and anything less than that is technically speaking not destroying the planet.
     
  10. Jan 28, 2017 #9
    One possible factor I was considering and curious about (and was hoping someone with far more knowledge could help on) is the localization of the event. The comet that wiped out most dinosaurs was located in one spot, while a nuclear war releasing 15 000 weapons would presumably be all over the place (probably concentrated in the Northern Hemisphere). Would that alter the dynamics in how the global effects played out? And would this make a large enough difference to matter on the global scale?

    And of course, the dangers of radioactive particles. How long and to what degree would they cause devastation to life in comparison to the aftereffects of a massive comet?

    So these kind of differences give me pause in assuming that nuclear war would be nothing compared to a large comet.
     
  11. Jan 28, 2017 #10

    ZapperZ

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    During this time with "fake news" and "alternate facts", I'm surprised that you are still this naive.

    Zz.
     
  12. Jan 28, 2017 #11

    Borek

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    Do you know a way of not allowing idiots to take over other than educating people and debunking nonsense?
     
  13. Jan 28, 2017 #12

    ZapperZ

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    Nonsense from valid sources, yes. Nonsense from blogs and charlatans, no. Isn't this why we don't discuss crackpottery in PF?

    Zz.
     
  14. Jan 28, 2017 #13
    This topic is simply not or has not been a very popular one in my lifetime. Maybe it was for those who really grew up in the 1960s through 1980s.

    Who is doing their doctoral theses on the effects of nuclear war? And where might I find these papers? Has there even been academic comparisons to the comet that wiped out the dinosaurs to possible nuclear war? I'm sure there has been some studying of extinction events but I'd be interested in studies in hypothetical ones.
     
  15. Jan 28, 2017 #14

    Anyone want to take a shot at this question rather than attacking the OP? (who believe it or not is merely curious about the topic)
     
  16. Jan 28, 2017 #15

    ZapperZ

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    Did you even try to look for these?

    https://www.osti.gov/scitech/biblio/6714529
    http://www.nature.com/nature/journal/v308/n5954/abs/308021a0.html
    http://www.astro.cornell.edu/academics/courses/astro202/TTAPS2_SciAm84.pdf
    http://onlinelibrary.wiley.com/doi/10.1029/JD094iD01p01127/full

    .....

    Should I go on?

    Zz.
     
  17. Jan 28, 2017 #16
    May I ask what I did to offend you? I'm thinking you have the wrong idea about the purpose of this thread (the "fake news" and "alternative facts" comments suggest that), and if so, let me go ahead and clear that up. This is strictly educational in purpose. There are no other motivations whatsoever. If you want to know, the answer is NO I am NOT an "alt-right" person, and this has nothing at all to do with the Right's desire to increase nuclear armament (I'm not even a conservative to begin with, if that even matters).

    It's a series of physics questions, and nothing more. One brought about by chance reading about the TNT equivalence of the dinosaur killing comet and comparison to the same output from nuclear weapons. Suddenly what I'd been taught my entire life (and blindly accepted, it's true) didn't make sense.





    Anyway, yes I looked for information before coming here. Unfortunately, my search skills were not sufficient enough to find information useful to me on the specific questions I have, for example: would smaller disturbances whose net TNT equivalence is relatively small but distributed globally (such as nuclear war) be more or less destructive to life and ecosystems than a more powerful but much more localized disturbance (such as a huge comet)? (one of your articles suggest distributed disturbances could be worse than a localized one, but gives nothing but a qualitative statement regarding that).

    Hopefully this thread can move beyond whatever the heck occurred here in the first few posts and on to the topic. (A first for me here... usually my threads have not annoyed people I'm seeking info from, and usually they have patiently directed me to what I wanted to know)


    While I appreciate the ease with which you found articles, regarding them:

    https://www.osti.gov/scitech/biblio/6714529
    ^I won't be able to access that paper until next year. But thanks for the effort.

    http://www.nature.com/nature/journal/v308/n5954/abs/308021a0.html
    ^Thanks but sadly again I can't read more than the abstract.

    http://www.astro.cornell.edu/academics/courses/astro202/TTAPS2_SciAm84.pdf
    ^This one is actually pretty useful to my questions. Unfortunately, it says there is no straight forward way to compare volcanic eruption dust cover to nuclear war, and little about the comparison between nuclear war and comets. It does, however, actually answer directly a question I asked regarding localized versus widespread disturbances. Also, it was informative on estimates of possible dust cover based on degree of nuclear war. It says the height of dust is dependent on the yield of the weapons.

    http://onlinelibrary.wiley.com/doi/10.1029/JD094iD01p01127/full
    ^Again sadly I won't have access until next year. The abstract is promising, but I wonder if it's going to tell me more than "nuclear winter is the likely result of nuclear war."​



    Summarizing the best article you posted (http://www.astro.cornell.edu/academics/courses/astro202/TTAPS2_SciAm84.pdf) with respect to the questions I had, in case someone stumbles upon this thread wanting to learn, based on what I understood of it (since again, I only made this thread because I wanted to learn):

    1. Optical depth of an aerosol can serve as an indicator of it's climatic effects.
    This has relevance to comparisons to volcanoes, since according to the article, while their particle size is idea for causing havoc in the local climate, the optical depth is relatively low. Also it has relevance to comets, as their optical depth of their dust is very high, according to the article.​

    2. The article also answers in the affirmative that spread out disturbances could cause more problems than localized ones of equal net energy.

    3. The article provides a clue regarding my most pertinent question: how does nuclear war compare to a large comet. The largest
    optical depth provided in this article for nuclear war scenarios is 10, while it mentions that the optical depth of dust from a comet could be as much as 1,000 for a short period of time. This suggests to me that a large comet could be much worse.

    It also says that the longer the optical depth is obtained, the more likely a new climate equilibrium will be reached. The article also states that the time the particles are at a high optical depth is dependent on the height. However I didn't notice it going into much detail regarding what differences there might be from particles expelled from a comet versus nuclear wars.

    This article states that they only considered one dimensions in this analysis, unfortunately. It suggests future studies might give better and more precise results. While it was useful, because it certainly offered some clues, I'm wondering if maybe my simple questions are ones that aren't known entirely. At least based on this article (which is old).​

    4. Widespread fires would alter the albedo, and I doubt that a single giant comet impact would have widespread fires like a global nuclear conflict.



    Conclusions relative to the original question:
    *By at least one variable, a comet would be far worse than nuclear war (optical depth of dust cloud).
    *However, many small disturbances could be worse than one large one of equal energy.
    *There is a lot more that needs to be studied on this topic (at least with respect to the article you posted that answered the most questions).​


    Anyway, thanks for the articles.
     
  18. Jan 28, 2017 #17

    russ_watters

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    Sure: maybe they are referring to the blast radius calculation described in the video. Try comparing the area covered to the surface area of the Earth.
     
  19. Jan 28, 2017 #18

    Astronuc

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    Well, all of the nuclear weapons are not Tsar Bombas. Tsar Bomba was a one time test. From the Wikipedia article: "the bomb had a yield of 57 megaton TNT (210 PJ). In theory, the bomb had a maximum yield of 100 megatons if it were to have included a U-238 tamper, but because only one bomb was built, this was never demonstrated."

    Clearly detonating 15,000 nuclear warheads would not 'destroy the planet', but it would probably make a good portion of the planet uninhabitable, and a larger portion marginal. Usually, 'destroying the planet' means destroying the infrastructure, e.g., dwellings, utilities, water, food and medicine unavailable, such that a large portion of the population would perish. Think of Germany, or German cities in 1945-1947, particularly the winters.
     
  20. Jan 29, 2017 #19
    I think you and the following poster are right about what they mean there. I appreciate the insight.

    This is good suggestion. Based on the blast radius of the Tsar bomba (22 miles according to google search), I'm thinking that 15,000 of them (an admittedly large overestimation) would cover:

    π(22 miles )2(15,000) = 23 million square miles. But the surface of the earth is 197 million square miles, so that probably isn't what they meant.


    If they meant surface area of cities... According to the following link, approximately 2.7% of the world's surface is urbanized. http://www.newgeography.com/content/001689-how-much-world-covered-cities

    So, 2.7% of 197 million square miles would be about 5.3 million square miles, and that is well below one third of 23 million square miles (of course it's based on a large overestimation. I don't know if I could get a true reasonable estimate, but I wanted to ensure maximum possible destruction in this scenario to see what is wiped out).


    I think this might be what they mean by "more than three times over." Thanks for the insight.



    If that is indeed what they were getting at (rather than destruction of all life, or literally tearing apart the planet), then it would seem just by raw blast radius coverage it is a correct statement. That certainly clarifies things for me on that. However, going through this thread and reading some of the articles posted suggests some huge complexities regarding what happens immediately after the blasts and the long time ramifications as well. I had suspected originally that if all of them were used and shot directly at cities it could very well pretty much end human society. Based on the above suggestions you guys have made, it seems that is pretty reasonable. Naturally there would be failed launches, and certainly missed launches (I'm sure some cities would escape), and obviously as the nuclear war progresses the ability to launch the weapons would decrease, probably exponentially.

    But this has all been pretty informative. I appreciate the helpful responses.
     
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