The Climate Bomb Redux

By Tom Yulsman | December 3, 2013 12:05 am
Atomic bomb Hiroshima Nagasaki Climate Bomb

Mushroom clouds blossom over Hiroshima (left) and Nagasaki (right) from atom bombs dropped by the United States on August 6 and 9, 1945. (Source: Wikimedia Commons)

Imagine four atomic bombs like the one that incinerated Hiroshima, Japan on Aug. 6, 1945 exploding in the atmosphere every single second of every day of every week and every month, year after year, ad infinitum.

That, says John Cook and colleagues at the web site Skeptical Science, is a good way to understand the excess heat that is building up in the atmosphere as a result of humankind’s emissions of carbon dioxide and other greenhouse gases.

Four atomic bombs’ worth of extra energy, every second.

My friend and fellow Discover blogger Keith Kloor called this, well, explosive comparison “The Climate Bomb.” Thus my headline, “The Climate Bomb Redux.”

I found it compelling at first. But despite my respect for Skeptical Science — a site I have used many times — I soon found myself taken aback by the comparison. I also began to wonder whether it really would help improve climate change communication, and also about the scientific context.

So I decided to investigate. This post is the result of what I’ve come up with. Overall, I think there are two main problems with the comparison.  First, it may have the opposite effect than the one intended by Skeptical Science. Rather than increase public understanding of climate change and thereby prompt action, it may just lead to greater polarization.

The second is scientific in nature: Four Hiroshima atom bombs of heat per second sounds like a whole lot — and the comparison is certainly scary. But there is a disconnect here that is likely to cause people to dismiss it: Despite all that energy, the global average temperature hasn’t exactly soared. Averaged over the whole globe, it has gone up by about 0.85 degrees C (1.5 degrees F) since 1880, according to the latest report from the Intergovernmental Panel on Climate Change. While that small amount amount is linked to significant changes in climate that pose all manner of risks, my guess is that for most people the image of a nuclear apocalypse doesn’t quite jibe with their own day-to-day experiences of those changes.

The overall problem is that there is a gross mismatch in scale between an exploding atomic bomb and our planet’s climate system. More about that as we dig deeper.

The Climate Bomb – Hiroshima Comparison

Just so you can hear it from the source, here’s the top of the article by John Cook at Skeptical Science:

When scientists add up all the heat warming the oceans, land, atmosphere and melting the ice, they calculate that our planet is accumulating heat at a rate of 2.5×1014 Watts. This is equivalent to 4 Hiroshima bombs worth of heat per second. When I mention this in public talks, I see eyes as wide as saucers. Few people are aware of how much heat our climate system is absorbing.

Global warming Hiroshima atomic bombs Skeptical Science

Click for information about the widget.

To better communicate the energy imbalance our greenhouse gases are causing, the folks at Skeptical Science have even released a widget that can be embedded in blogs. “The widget shows the amount of energy that has been and continues to be added to the earth’s climate system, expressed in ways that non-scientists can more easily relate to,” Cook says.

My bet is that if you’re really concerned about climate change, have followed the issue closely, and believe that urgent action is necessary, the Hiroshima comparison has fortified you in your beliefs. And you probably think that it could help bring others over to your way of looking at the issue.

Conversely, if you consider yourself a skeptic of climate change science, think the risks have been overblown, and oppose intervention in the economy to mitigate climate change, you probably find the comparison outrageous, and maybe even offensive.

In other words, how you interpret and react to the comparison is most likely determined by what you already believe, and that it’s therefore unlikely to have the impact that Jon Cook and the others at Skeptical Science hope for. In fact, it’s more likely to contribute to the polarization that has stymied action on climate change than ameliorate it.

Lack of Public Understanding is Not the Problem

The assumption that seems to underlie efforts like this is that if improved communication could lead to better public understanding then we’d get some action on climate change before it’s too late.

As a science journalist, I’ve been dedicated to the idea that an informed public is essential for democracy. But I also realize that this goes only so far when it comes to complex scientific issues involving risk, and climate science especially. It is incredibly complicated, and there’s just no way many non-scientists are going to gain a deep understanding of it, Hiroshima bomb comparisons notwithstanding.

And even if they could, it’s not clear that a lack of understanding is what’s actually holding back public consensus on climate change.

Consider medical x-rays and childhood vaccines, both complicated issues involving risk. While there is some controversy at the fringes, the overwhelming majority of us get an x-ray when our doctors recommend one, and most parents get their kids vaccinated. And I would venture to guess that most of us have no clue what the science actually says about these risks.

Dan Kahan, a professor of law and of psychology at Yale and a member of the Cultural Cognition Project, has written a lot about this. Here’s a snippet from one of his blog posts last May:

 . . . if you notice all these boring, non-polarized forms of science-informed risk regulation, you’ll realize that the thing that makes some issues become polarized can’t be lack of public knowledge about the science surrounding them.

It’s true that members of the public don’t know science much about climate change, nuclear power, the HPV vaccine, etc. But the public doesn’t know anything more about the science relating to the vast range of issues that fail to generate polarization.

So lack of understanding about climate change isn’t the issue, he argues. Polarization is. Writing in Nature last year, here’s how he put it:

The trouble starts when this communication environment fills up with toxic partisan meanings — ones that effectively announce that ‘if you are one of us, believe this; otherwise, we’ll know you are one of them’. In that situation, ordinary individuals’ lives will go better if their perceptions of societal risk conform with those of their group.

I very much doubt that John Cook and his colleagues at Skeptical Science would be happy with increased polarization on climate change. But I fear that is what the Hiroshima comparison will accomplish.

A Lack of Scientific Context

Even if it’s true that energy is building up in the atmosphere at the rate of four Hiroshima bombs per second, important context is missing.

It’s an issue of scale: The Hiroshima atomic bomb released its energy over a relatively small geographic area, and almost instantaneously, whereas the radiative imbalance from anthropogenic greenhouse gases is causing energy to build up in the incredibly complex climate system, over a vast geographic scale, and on a timeframe best measured in years and decades.

So the Hiroshima comparison is only part of the story.

James White, a colleague of mine here at the University of Colorado, and director of the Institute of Arctic and Alpine Research, agrees. Here’s what he had to say, in an email message:

I think your instinct is correct. The Earth is a very large place, and the total solar energy is much, much larger than the accumulated imbalance of which they speak. For example, small, natural perturbations in climate equate to many, many Hiroshima bombs. That said, the Earth is indeed accumulating energy, and the problem of how to translate that into terms people understand is daunting.

White’s point about small natural perturbations are echoed by Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research who has published estimates of energy flows through the climate system. To put the atomic bomb comparison in proper perspective, he said this: “Think of the convective cloud from a nuclear explosion as being more like the energy in a small, single thunderstorm.”

With this in mind, we can change the comparison: The energy that’s building up in the atmosphere as a result of our actions is roughly equivalent to five small thunderstorms every second. Somehow, that doesn’t seem quite so apocalyptic, right? Thunderstorms are popping off all around the world every day.

Compared to the amount of incoming energy from the sun, the human impact on the timescale of a year also does not sound quite so apocalyptic. According to Trenberth, that incoming solar energy is equal to about 175 petawatts (175 plus 15 zeros). “About 120 of those petawatts is absorbed and is what drives the climate and hydrological system,” Trenberth says. “That is the natural flow of energy through the system.”

How does human-caused global warming compare? It amounts to about 0.46 petawatts every year. In other words, the natural flow of energy through the climate system in one year is 275 times greater than our contribution.

Of course, over the long run that extra heat really adds up, and is already causing the climate to change. And that’s the whole point: Climate change is a long-term phenomenon, not one that’s best measured on a timescale of seconds.


CATEGORIZED UNDER: Climate, Global Warming, select, Top Posts
  • Buddy199

    The comparison is sensationalistic and desperate. Like a child throwing a fit and holding his breath to get attention.

    • zlop

      How many exploding Kids will save the Climate for future Ice Age dwellers ? “10 10 – No Pressure” uTube

    • schmoepooh

      Why don’t you throw a fit and hold your breath?

  • BarryWoods

    Dr Warren Pearce (Nottingham University) at the Making Science Public blog discussed the Hiroshima framing and similar problems with it a few months ago..

    John Cook and Dana Nuccitelli (Skeptical Science) contributed in the comments (as did I) and just did not seem to comprehend the problems with it, also identified in the article above.

    When the App was launched, see this Guardian article by Dana, the criticisms remained the same.

    Dr Warren Pearce:

    “What is bizarre is to think that people will not imagine mushroom clouds and suffering when offered this analogy.”

    The fact that they went ahead anyway (a number of climate scientists also tweeted to John, their displeasure/helpfulness) perhaps reveals a lot about Skeptical Science.

  • BarryWoods

    Dr Doug McNeall (Met Office) had some interesting comments about this – via twitter (my bold)

    John Cook ‏@skepticscience
    New website about our planet global warming at 4 Hiroshima bombs worth of heat per second

    Doug McNeall ‏@dougmcneall
    @skepticscience Hi John, as I said before, I think this is a silly way to describe warming: meaningless, and a bit shrill.

    Doug McNeall ‏@dougmcneall
    @AGrinsted thing is, @skepticscience knows that this is a poor comparison – it’s been pointed out before.

    Doug McNeall ‏@dougmcneall
    @AGrinsted @skepticscience > because climate change is nothing like atom bombs.

    Doug McNeall ‏@dougmcneall
    @AGrinsted @skepticscience But, actually, the comparison makes the information available to the public *poorer*, >

    Doug McNeall ‏@dougmcneall
    @AGrinsted @skepticscience So, , what do we have – a nice soundbite that gets picked up by msmand touted around a bit.

    I think in the next tweet, Dr Doug McNeall, echoes Prof Richard Tol’s concerns earlier….

    Doug McNeall ‏@dougmcneall
    @AGrinsted My problem is that the association of death and destruction is also easy to grasp.

    Doug McNeall ‏@dougmcneall
    @AGrinsted @skepticscience Doing it in a way that holds deep and terrible cultural resonances with millions of people is not great.

    if you look at Doug’s twitter feed that day, he asked his climate scientist followers what they thought of the app, and it was broadly negative..

  • BarryWoods

    When I pointed out Dr Doug McNeil opinion about the Skeptical Science Hiroshima App to Dana, his response was priceless.. (appeal to authority, a weak one at that)

    “John Cook is a social scientist. Given that this is a communications issue, frankly he has more expertise than climate scientists on this subject.” – Dana Nuccitelli

    I thought of pointing out that DR Warren Pearce was very much a social scientist,

    and unlike Mr John Cook , already had his PhD, but I what would be the point.. nothing will penetrate the SkS mindset.

    • cloudpoint

      There is nothing wrong with an appeal to an authority that has the proper expertise. Nothing would ever get settled if this was not an acceptable argument. The common fallacy is actually argument from “unqualified authority”. John Cook fits the category of having proper expertise based on having a PhD in the area of communications study.

  • Keith Kloor

    Great post, Tom. A few additional thoughts:

    By now, I think anyone that writes about climate change in any capacity is well aware that anything he or she writes is potential fodder for the climate wars. I’m betting that Cook et al knew their widget would trigger a hostile reaction from climate skeptics; I doubt the Skeptical Science folks care about that, since climate skeptics are not their intended audience. However, I’m also betting that Cook et al were not expecting the mixed-to-disdainful reaction from various climate scientists.

    That said, let’s assume for the sake of argument that this latest rhetorical device was aimed at the great middle of the divide–those who are indifferent to the climate change issue or those whose who are aware but don’t have a high level of concern. These people don’t pay close attention to insidery back-and-forth retorts, the climate blogs, etc. If this widget can snag their attention in a “cognitively sticky” fashion (as John Cook explained on Twitter), then the widget creators would probably consider that a success.

    Of course, the actual scientific merits of the Hiroshima analogy issue are a separate issue, which your post has helpfully probed.

    • Tom Yulsman

      Thanks Keith, for these comments and getting the whole thing rolling.

      • Bill C

        Much more helpful might be a comparison of the accumulated energy from climate change to the actual energy used by people. AFAIK the energy accumulation rate (power) from GW is about 500 terawatts where human energy use is about 10. So GW supplies 50 times as much power as all the energy we actually use.
        One other thing, Tom – you say the energy accumulating in the atmosphere is xxxxxx….I think the actual number compared to the atom bombs includes ocean heating which is >90% of the increase.

  • doug masnaghetti

    The atom bomb comparison is exactly what you would expect from a left leaning climate pseudo-scientist. Clearly the average american has no better intuitive feel for the energy released from an atomic explosion than they do for the amount of energy driving climate change. So why would this nimrod choose something americans have no intuition for to help them get a “deeper” understanding of climate change? The answer is fear, the attempt to tap irrational fear in americans and link it to climate change. The bizarre freaks claiming to be scientists simply aren’t. They do not poursue truth, the pursue narratives. Climate scientists are as repulsive, deceptive, and misleading as the average american “journalist”.

    • Tom Yulsman

      Doug, your ad hominem attacks undercut your credibility, as do your broad, sweeping generalizations about literally thousands of scientists working in dozens of different fields. If you want to be taken seriously by people outside your own tribe, I have a suggestion for you: be serious. But I suspect it just makes you feel smugly superior to call people you don’t know “nimrods” and “bizarre freaks.”

      • Tom Yulsman

        And Doug, if you want an example of how to be serious, see Barry Woods’ comments below.

      • Matthew Slyfield

        Aside from the name calling, Doug is correct. The only rational reason to select atomic bombs as the comparison for global warming is fear mongering.

        • schmoepooh

          Not necessarily. It is a vivid way of quantifying it. It’s the prospect of global warming, the extremes that accompany it that is alarming.

      • doug masnaghetti

        No, they are nimrods and bizarre freaks. They are political shills masquerading as scientists. They have politicized the science of climate change. The do not pursue truth but political narrative. You need look no further than the alarmist predictions that time has discredited and the fact that these “scientists” destroyed decades of original climate data in the 80s’ No real scientist would ever, ever do that! Do some research before you try to deny these points. And yes, I will;l insult these freaks because their manipulative, politically driven declarations are an insult to all thinking Americans.

      • schmoepooh

        Well said. Narcisistic.

    • zlop

      “left leaning climate pseudo-scientist” ?
      Part of the $80 Trillion Carbon Disclosure Project,
      advancing Global Tyranny,
      They are Climate Deception Mercenaries.

      • schmoepooh

        Ah yes! The old agenda 21!

        • zlop

          Agenda 21 is preparation for the prophecy written in the Georgia GuideStone.

          • schmoepooh

            Your a Scientologist!

          • zlop

            Not a Scientologist — not any gist.
            (attended a course once,
            got my money back)

          • schmoepooh

            Good on you!

          • zlop

            There are skills to be acquired.
            Somehow, Scientology seemed
            oppressive — some franchises
            might be useful.

          • schmoepooh

            Oppressive, run by madmen and homosexuals who use it to recruit naive young males.

          • zlop

            Yes, there seems to be that angle.
            Addition to thethans running around,
            Control is by personal information divulged
            (similar to initiations into secret societies)

          • schmoepooh

            History is littered with temples, prophecies and messages from God “discovered” (with one eye on its possibilities) and then attributed to a moment of “divine” grace. The Georgian tablets were probably erected on behalf of Howard Hughes or a bunch of wealthy Southern Baptists.

          • zlop

            $atan operates, announces
            through his mercenaries.

          • schmoepooh

            Yes and they pollute the planet on the process.

          • zlop

            Not a Noble lie that CO2 is pollution,
            (CO2 cools only slightly)

          • schmoepooh

            Not true. CO2 traps heat rebounding from earth. Basic high school science. Simple experiment. Google it.

          • zlop

            Greenhouse gases lower clouds.
            Lower clouds imply lower surface temperature (adiabatic lapse (-g/Cp)

            Ice Age coming: “Declining global average cloud height: “A significant measure of negative feedback to global warming”

          • schmoepooh

            I’d be interested in the source of that. Got a reference or link?

          • zlop

            Simplest reasoning (explanation) for greenhouse gas cooling I could think of.

            dew point, condensation, adiabatic lapse
            More insights

            “‘Greenhouse Gases’ COOL the Earth –
            Principia Scientific International”

            “Greenhouse gases cool planets:
            Volcanos warm them | Tallbloke’s”

            “Greenhouse Gases in the Atmosphere
            Cool the Earth!” Nasif Nahle

          • schmoepooh

            Always check your sources on the broader generally reliable search engines like Wikipedia. Those wankers we’re set up to confuse people who don’t have scientific understanding, for example religious literalists. It’s called astroturfing and is financed by by some of the most unscrupulous people on the planet. Kock brothers for example. Buy a real book not Internet. You are searching for sources that tell you what you want to hear. I don’t talk to people who can’t think for themselves.
            Volcanoes cool. GHGs warm. Otherwise the planet would be uninhabitable. Don’t you trust your own scientific establishments?

          • zlop

            Enough pontificating — come up with a reason why the lowered cloud reasoning could be wrong — then we can quibble
            (heat capacity of CO2, CH4, air …
            objections to the Saturated Greenhouse Effect, Atmospheric Thermal Effect (ATE))

          • schmoepooh

            Sorry don’t talk to idiots. Bye.

          • zlop

            Relying on basic principles,I explained it
            simply — You have not put in a minimal
            effort, to try and understand.

    • David Clemmer

      The first comparison I heard between GW and atomic bombs was from the lips of Rush Limbaugh on his radio show ca. 2006. Essentially he said, “How can humans cause GW? Not even nuclear bombs can do that!” I won’t comment on his scientific credentials, but it was interesting to see that his point of reference for all things powerful was a nuclear weapon.

  • zlop

    “all the heat warming the oceans, land, atmosphere and melting the ice” Good to know, that with increasing uncertainty, the heat is cooking the Monsters, in the Marianas Trench.

  • William Rose

    As one scientist put it (I am paraphrasing here), show me the climate model that predicted the lack of warming we have seen over the past decade or two? Any scientist worth being called such will tell you, successful prediction is the only true measure of the value of a model. I am not saying human activity is not contributing to global warming. What I am saying is that before we spend hundreds of billions of dollars we should have a predictive model that can tell us what the money will accomplish. Anyone can model the past. Just as you wouldn’t invest your money in stocks today based on a model that got the market from teh 1990’s – 2013 completely wrong, we shouldn’t invest billions based on climate models that have been wrong for the past 15 years or more.

    • cloudpoint

      There hasn’t been any real lack of warming over the time frame you mentioned. The actual climate can’t be properly measured well in term of trends over short periods (the signal is dominated by weather noise) so there’s no comparator to invalidate the models. The slightest inaccuracy in the observation data completely changes what we think happened. Climate models are not expected to ‘predict’ weather. They project climate trends, and these can only be assessed over 30 year time frames or longer.

  • Donald Baker

    Since the climate is never static, would we prefer global cooling to global warming? Whether human interaction is a significant source, the planet is warming and has been for over 12,000 years. Its inter-glacial time my friends.

    • schmoepooh

      Cycles require energy my friend. Go read some physics.

      • Donald Baker

        What’s your point? How do we know the Earth isn’t just bouncing back from the Little Ice Age? Go read about it, my sarcastic friend.

        • Hawkeye72

          Right. Maybe we’re bouncing back from the ice-age Time Magazine predicted in 1973.

        • schmoepooh

          I can see you still don’t get it. Climate doesnt bounce around by itself. If it cools there’s a reason. If it warms there’s a reason. Laws of thermodynamics.

        • schmoepooh

          Bouncing doesn’t feature in climate science.

      • Hawkeye72

        I would tell you to go read “The Cat In The Hat” but it would be over your head.

        • schmoepooh

          What are your qualifications?

  • schmoepooh

    Forget about John Cook and the nuke analogy. Just focus on the basic science, the fact that it has to go somewhere and that is endorsed by every international science agency on the planet as well as the US defence establishment, Homeland Security, CIA, General Electric (and many other large corporations with scientific resources), numerous States and Counties in the US and 97% of qualified climate scientists and other scientists not dependant on Fossil Fuel largess.

  • Tommy_D_Cosmology

    Conservatives used to respect established institutions, like NSF, The National Academies, etc. Now they really think every credible institution is actually conspiring to make this up! Why do they think this? For the same reason they hold all their other political and social beliefs: they do not give a sh#t about anyone but themselves. They are selfish a$$holes through and through.

    • Thomas Dobbins

      No, it’s because it’s a FACT that “established institutions”, GW scientists, Big Oil, Big Pharma, politicians, the American federal government, etc LIE to us almost every time they bother to communicate with us…

  • Hawkeye72

    This is,by far, the dumbest article I have ever read on any subject.It’s right up there with the Cheshire cat disappearing.

    • cloudpoint

      Almost any article at WUWT will surpass this one in dumbness. It’s good that you don’t visit that web site.

  • Thomas Dobbins

    BS. Where I live in Florida, temps have been going DOWN for six years now. Click on the link, check it out…then substitute your city for mine and see the results.

  • Georges Bombezin

    Interesting debate that shows that polarization resolve nothing and that, somehow, reminds me of american politics at the present.

    • zlop

      Already resolved that, you are guilty, and will be
      more controlled — Ice Age or Dino times.

  • Christopher Squire

    Re: ‘According to Trenberth, that incoming solar energy is equal to about 175 petawatts (175 plus 15 zeros) . . How does human-caused global warming compare? It amounts to about 0.46 petawatts every year. In other words, the natural flow of energy through the climate system in one year is 275 times greater than our contribution.’

    A petawatt is a unit of power not of energy. 275/0.46 = 380 not 275. This is nonsense as written.

    • zlop

      “data are filled with speculations and -very evident- unreal processes … Trenberth et al aren’t being objective. It’s why they’re pulling out fictitious amounts of energy from underneath the sleeve”

    • cloudpoint

      Indeed they are speaking about flows of energy, not amounts of energy. They could have been more explicit but this is implied by the use of watts as the unit of measure. The discrepancy is probably due to albedo adjustment that wasn’t explained, at least the ratio of the difference, 30%, appears correct. The human contribution is small but it is relentless. In theory, at the same rate, in 270 years we will have matched the inflow of energy from the sun (but we would all die long before that stage).

  • Mike Shefler

    “my guess is that for most people the image of a nuclear apocalypse doesn’t quite jibe with their own day-to-day experiences of those changes.”
    The understatement of the year.

  • zlop

    “good way to understand the excess heat that is building up”
    But were could this excess heat be hiding ?

    “mid-Pliocene (3.3–3 mya) was 2–3 °C higher than today”
    “average temperature of the entire ocean during the mid-Pliocene was approximately one degree warmer than current conditions, showing that warming wasn’t just at the surface but occurred at all depths”

    See Dr. Roy Spencer “Latest Global Temp. Anomaly (Nov. ’13: +0.19°C)” —

  • cloudpoint

    The Hiroshima bomb comparison doesn’t really work for me given its lack of correct scale and differing context, but I am one of those people that already formed an opinion from more basic science. For those that have formed no opinion yet, it might be a useful attention-getter, though not a persuader. Getting the attention of those that have not thought about a matter is the first step.

  • Brian Schmidt

    “if you consider yourself a skeptic of climate change science, think the risks have been overblown, and oppose intervention in the economy to mitigate climate change, you probably find the comparison outrageous, and maybe even offensive.”

    My response is to ask Tom or anyone to point to a statement by denialists about the science that is a correct depiction of the science and is outrageous. If they can find something, then maybe they have a point. Otherwise, not so much.



ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.


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