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Meteors, Nuclear Tests and Global Warming

Filed under: — gavin @ 15 March 2006

What is one to make of a recent press release and submitted preprint blaming global warming on the Tunguska meteor event in 1908? Well, although it is not unknown for impact events to affect climate (the K/T boundary event springs to mind) there are a number of hurdles for any such theory to overcome before it moves into the mainstream from the wilder shores of unsubstantiated speculation.

Firstly, one would anticipate that immediate effects of the impact on climate would be strongest near the time of the impact (allowing for some inertia in the system) and decay away subsequently. Secondly, the timescales for any mechanism associated with the impact (in this case disruption of the atmopsheric water vapour) would need to be in line with the change one hopes to explain. And thirdly, one has to show that this explanation is better than the alternatives. Unfortunately, none of of these requirements are met by this hypothesis.

An impact hypothesis is usefully contrasted to the impacts of a large volcanic eruption like Pinatubo in 1991. There was a very clear dip in temperatures a year or so after the eruption and a subsequent relaxation back to normal. No such event (warming or cooling) is recorded in 1908 to 1910. The timescales for water vapour in the lower atmosphere is on the order of days (see our previous post on the subject), while in the stratosphere it is a a few years. But there are no reservoirs of climatically important water vapour amounts that could still be causing the impact effect to be felt (and to accelerate!) almost 100 years later. And finally, current theories based on greenhouse gas increases, changes in solar, volcanic, ozone , land use and aerosol forcing do a pretty good job of explaining the temperature changes over the 20th Century. It’s very hard to see what this idea has to add to that.

In an additional twist, it is suggested that atmospheric nuclear tests from 1940s to the 1970s masked out the effects of the impact due to the supposed mixing up of tropospheric water vapour into the stratosphere after every explosion. This is even odder since stratospheric water vapour is actually quite a significant greenhouse gas, and had this occured to any large extent, it would have been a warming factor, not a cooling one.

So while the physics being invoked here is barely worth discussing, a more interesting question might be why the University of Leicester thought that this was worthy of a press release in the first place, and why this got any traction in the media at all. True, it didn’t get much attention, so maybe there is some hope for science journalism after all…


69 Responses to “Meteors, Nuclear Tests and Global Warming”

  1. 51
    Russell Seitz says:

    Dear Gavin:
    No ad hom, intended , but it may be ad rem that the Moscow Institute is the one ill famed for ‘corroborating ‘ bad models by simply rerunning them on older mainframes.Before it went into Lukoil’s service ,its former Director Gerasimov was guardian of the party line on ‘nuclear winter’.

    Lest we forget, his unenthusiastic protege Vladimir Alexandov , was hustled off into oblivion in March ’85 .

    The Tunguska analogy is pretty funny, and there is certainly plenty of comedy of manners in the climate wars , but I think we can agree that liquidating modelers goes beyond the limits of tasteful precedent.

  2. 52
    joel Hammer says:

    What is one to make of a recent press release and submitted preprint blaming global warming on the Tunguska meteor event in 1908?

    If global warming were less politics and more science, what you would make of it is an interesting hypothesis which should be looked into, not a crackpot idea which should be ignored and yes, not allowed to be published for fear of causing confusion.

    Naturally, the idea will be dimissed as unlikely without much thought. But, they laughed when it was suggested gastric ulcers were due to an infection.

    [Response: Not all ideas are created equal. -gavin]

  3. 53

    Re #44 — it’s dangerous to go up against Ray on a climate issue, especially for someone like me who has no formal training in climatology. But I do want to say that I still think Nuclear Winter might be a real threat. Turco et al. reexamined the issue in their 1991 paper, and concluded that there were serious flaws in the ’84 and ’86 counter-papers (by Schneider and Thompson, if I remember correctly) — e.g. a plume height off by a factor of three.

    [Response: Not so dangerous, I hope! To clarify, I didn't mean to say it wasn't a threat -- just that the immediate and more established consequences of nuclear war are a greater and more clear threat, so that nuclear winter doesn't change the calculus of terror as much as was thought, On the other hand, nobody expected the ozone hole until it happened, so it must be admitted that there are surprises in the climate system that are hard to anticipate. I certainly hope we'll never get to test the nuclear winter theory. --raypierre]

  4. 54
    Stephen Berg says:

    Re: #52, “If global warming were less politics and more science…”

    That statement just threw your whole message into disrefute.

  5. 55
    Joel Shore says:

    Re #52: It is not for political reasons but for valid scientific reasons that peer-review has come into being. In fact, allowing an article to be published in a scientific journal when it contains serious elementary errors is a more political response than subjecting it to the same standards of peer-review that other articles must undergo. It sounds like you are in favor of what some on the Right might term “affirmative action” for articles that go against the consensus views on climate change. (And really, this would be “affirmative action” in a caricatured sense since this is the kind of thing that has been ruled unconstitutional when applied in the sociopolitical realm…i.e., “affirmative action” in hiring or admission to colleges does not compel [or even allow] one to admit clearly unqualified people just because they are an underrepresented minority).

  6. 56
    Paul says:

    According to the press release, the theory was “revealed at a meeting at the University of Leicester (UK) and is being considered for publication in the journal ‘Science First Hand’.”

    Buried at the end of the article it then states that the author of the theory “visited University of Leicester in April 2005.”

    So the press release is based on a talk that took place 11 months ago. And I’ve never heard of Science First Hand. That’s…that’s pretty embarrassing for the university press office to put out this kind of release.

    It raises questions about professionalism.

    [Response: I hadn't heard of the journal either, but it was identified a few comments back. Science First Hand seems to be a popular science journal, something like a Siberian version of Scientific American. I agree wholeheartedly that something must have gone very wrong at the Leicester press office. --raypierre]

  7. 57
    Brian Jones says:

    Physorg didn’t take it down, it’s still there http://www.physorg.com/news11710.html

  8. 58
    Hank Roberts says:

    For comparison:

    Tunguska — 10-15 megatons, 5 to 7 km high airburst, flattened trees on ground and started fires

    Tsar Bomba: >50 megatons. Quotes from this article: http://www.damninteresting.com/?p=214

    “detonated … at approximately 13,000 feet [4 km]… The giant fireball reached from ground-level to about 34,000 feet [10.4 km] …. The mushroom cloud … stretched sixty kilometers into the sky…

    “The ground surface of the island has been levelled, swept and licked so that it looks like a skating rink. The same goes for rocks…. their sides and edges are shiny. There is not a trace of unevenness in the groundâ�¦ Everything in this area has been swept clean, scoured, melted and blown away.”… the area of complete destruction had a radius of twenty-five kilometers from ground zero.

    See the fireball viewed from the plane that dropped the bomb, here:

    http://video.google.com/videoplay?docid=2046393742348211186

    Conclusion — hard to imagine the one Tunguska event would have started warming, and all the nuclear tests that followed would have paused the warming. Coincidence seems more likely to me.

  9. 59
    Jason says:

    I have a question and this is the right place – does anyone know of any research that looks into what effect, if any, several decades of nuclear testing itself could be having on the climate? Seems to me that adding that much energy (equivalent to dozens of Tunguskas) directly to the upper atmosphere and oceans over an extended period of time is bound to do something. It occurred to me after reading this article. And that would explain why there was no spike and drop-off soon after the T.E. itself.

    Just wondering.

  10. 60
    Hank Roberts says:

    I can’t do the math, but the question you’re asking is the one that was asked in the Russian article that got this thread rolling, so you’ll probably find your best answer in previous postings. The experts don’t seem impressed by the idea; see the “Nuclear Winter” discussion of a few decades ago. Note that for the ‘Tsar Bomba’ I quoted above most of the heat went straight into space.

    I think it’s the difference between a flashbulb and a campfire — the campfire will warm you, even though it may not be as bright momentarily.

    As to total heat involved, you’d be comparing the amount of heat the Earth receives from the sun annually (this might be a place to start):
    http://oceanworld.tamu.edu/resources/ocng_textbook/chapter05/chapter05_01.htm
    with the heat produced by the individual nuclear tests; this might be a place to start:
    http://hypertextbook.com/facts/2000/MuhammadKaleem.shtml

  11. 61
    Coby says:

    Re 59,

    It is sobering to actually crunch some numbers, which I won’t do but have seen done, and realize how puny we are. For example, the total energy expended in one major hurricane is equivalent to dozens (or more, I can’t recall) of very powerful H-Bombs. So I think all the world’s nuclear tests would not amount to even one busy hurricane season.

  12. 62

    There are probably a lot of legitimate questions to be raised against Vladimir Shaidurov’s “Silver Cloud” theory of global warming: but leave Occam’s Razor out of it! This really isn’t a good reason to discard the theory. Shaidurov’s theory may indeed be vulnerable if his understanding of the mesosphere is defective (we know very little about this region, even now), but the theory fulfills Occam’s Razor so well that I’ve actually included it in an essay on Occam’s Razor at http://logictutorial.com/occam.html
    which also includes a general discussion of how our simplistic understanding of Occam’s Razor may have delayed any response to global warming and human industrial activity for decades.

    I do expect that the “silver cloud” theory is false, if only because most surprising ideas with only a few weeks of provenance turn out to be false; but mere novelty is no reason to rule it out of court! There’s much more on Occam at logic tutorial.com, so I won’t belabor these points here.

    The first criticism listed, that the effects would be local, is absurd. The mesosphere is 50km up and effects there would not remain local very long – even the initial pressure wave was detected as far away as Britian at the time, with the instruments then available, and at the surface of the earth. How likely is it that the effect would still be local, nearly a hundred years later?

    The second objection isn’t even comprehensible to me as stated – does this suggest that the largely smooth change in global temperature is disconfirming? Or that the interruption in that smootheness is disconfirming, instead? Or that the change should have been faster? Or slower? And just why, given what putative mechanism? I find myself unable to interpret this objection, as written, so I’ll have to wait for clarification.

    Re another objection: comparable very high altitude nuclear tests have never been conducted. As I say in the Occam article, that may be just as well, to say the least.

    It is very surprising to me, even shocking, how little media attention this theory has gotten. Doubtless the murder of a minister this week is a more critical issue for our times.

    I’m for any story that helps keep our attention on global warming, and the reality of that peril, because I’m convinced by the science that it’s a profound problem. Anything that gets more people to look at the actual graphs of earth’s temperature data over the last century is fine by me.

  13. 63
    Hank Roberts says:

    Russell — When you looked up the altitudes and magnitudes for high elevation nuclear tests, and compared those to the Tunguska elevation and magnitude estimates — What numbers did you find? Where did you find them? Please give us your source.

    I posted what I found with references above. Your say you have found different information. Where did you find the numbers you rely on, please?

  14. 64
  15. 65
    Hank Roberts says:

    Promise of a series of articles in Nature and other journals based on one well documented event in 2005,
    http://www.sandia.gov/news-center/news-releases/2005/physics-astron/lidar.html
    mentioned as a challenge to the climate modelers to incorporate dust deposited in the stratosphere. Although I imagine if it’s deposited on a longterm average basis it’s just background, unlike a major volcanic explosion.

  16. 66
    S. Trap says:

    Um, one thing the above article does not explain… if not the Tunguska event, what DID cause the sudden recorded upswing in global temperature that began around 1909 Shaidurov is claiming?

    I’m guessing it wan’t the Tunguska event. But the data Shaidurov presented seems to imply that *something* must have changed around then that caused an upswing in global temperatures. His conclusion that it must be Tunguska is a leap.

    What someone needs to do is : A) check his data! and B) *if* it turns out to be legit, look for alternate explanations and explore them.

    It is his data that needs to be looked into, not his theory as to why that data is what it is. The article above does not mention the data at all. But it’s important. Beacuse *IF* the data is correct and tempertaure was cooling through the 19th century, but suddenly started a slow rise beginning in early 20th century, the cause is likely NOT fossil fuel emmissions. (one would expect the rise to begin sooner in that case)

    [Response: Don't over-interpret little wiggles in the graph. Natural variability and the known forcings explains it as well as is needed - William]

  17. 67
    Hank Roberts says:

    Seems likely these events are happening regularly enough to be averaged out as a background — but the climatologists can’t know about most of them!
    From http://www.space.com/scienceastronomy/astronomy/classified_impacts_000502.html

    “… Between 30 to 50 times a year, scientists say, a fireball comes screaming through Earth’s atmosphere, but chances are you never hear about most of these intruders. Since the late 1970s, military satellites have spotted about 400 such events. So far most of the data have remained classified. Scientists estimate that nine out of 10 fireballs remain out of public and scientific view. …”

    I also found mention that high altitude dust trails from meteors appear on LIDAR (laser optical ‘radar’) used to look at high clouds. This makes me wonder if there’s a group of climatologists who have appropriate security clearances who get to work with data from the military/security sources (including also the navy/submarine salinity and current records).

    Many decades ago I spent a summer at a marine biology program, and recall that the French, British and US marine biologists had to get together at bars after conferences to compare their sonar information. Each country’s research programs used sonar equipment supplied by their national Navy. Each country’s equipment had cutouts built in so the researchers would not see anything that could compromise national security (submarines, and whatever else they were using). And … duh … each nation’s cutouts were different. So over drinks, the scientists could piece together a complete picture of what was going on in the ocean. That was early in the 1960s, I think, maybe even earlier.

    Presumably that’s no longer a workable tactic for today’s scientists around the world. But I hope having at least a few fully informed scientists is part of our policy. Research can be published even when the exact data is secret and details of individual events are obscured — I hope! — and still give climate scientists useful information. If we don’t have such a program in place, we ought to, and have the journals accept papers with different rules when the underlying data collection is from classified sources.

    End of rant, just hoping it’s happening.

  18. 68
    Do says:

    Why the pither and pother – this cold United Kingdom could do with some warming up!

  19. 69
    llewelly says:

    Why the pither and pother – this cold United Kingdom could do with some warming up!

    (a) Changes in precipitation, growing season, and ‘burn days’ may force farmers in many areas to change crops. Some famine may result.

    (b) Sea level rise. Under a ‘business as usual’ (IS92a) scenario, the Hadley Centre projects about 40cm of sea rise by 2100 (1). Imagine London, Edinburgh, Liverpool, etc, with 40cm of sea rise.

    (c) Heat waves, like this will become more common.

    In addition, please see the IPCC TAR’s section on impacts.

    (1) See this graph, from here . Compare to the IPCC TAR’s projections in this graph from http://www.grida.no/climate/ipcc_tar/wg1/429.htm . The IPCC TAR talks about the impact of sea rise here .

    If you’ve heard ’7 meters’, that is how much ice is locked up in Greenland’s ice sheet, and therefor, how much sea rise we’ll see if and when Greenland’s ice sheet melts, which is expected to take anywhere from centuries to millennia.


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