August 14, 2013, by Warren Pearce

More heat than light? Climate catastrophe and the Hiroshima bomb


The Hiroshima bombing

There has been some discussion on Twitter today (14 August) about the wisdom or otherwise of measuring the heat being retained by the Earth in terms of Hiroshima bombs. The analogy is presented by John Cook and Dana Nuccitelli on their Skeptical Science blog, drawing on an academic paper by Church et al to describe the heat retained as equivalent to four Hiroshima bombs per second.

I have no reason to doubt this. However, choosing the most effective metaphor involves more than simply finding an analogy that accurately conveys a specific energy equivalence.  The very purpose of a metaphor is to help make the incomprehensible familiar in order to make a point. Asking whether it is accurate or not is not enough.

A problematic problem

The persistent problem with attempting to communicate climate change is that it represents an un-situated risk. As Mike Hulme describes it in Why We Disagree About Climate Change (p.196):

The source of the risk is distant and intangible – no-one can see climate changing or feel it happening – and the causes of the risk are diffuse and hard to situate.

Of course this is not to say that climate change is not a problem. However, the very nature of the problem is itself problematic. It is difficult to motivate political action around a problem which is so intangible, particularly when compared to classic environmental problems such as smog, floods, acid rain etc. which are localised and material. (As an aside, perhaps this means climate change is not an environmental problem at all?)

In this context, one can see the constant problem facing the ‘climate change communicator’:

Q: “How can we make this un-situated, incrementally increasing risk ‘real’ to the general public?”

A: “How about atomic bombs? Situated risks don’t come much bigger than that…”

So the Hiroshima meme was born.

To reiterate I am not casting aspersions on the accuracy of the data comparing the heat released by Hiroshima bombs to that being retained in the atmosphere. Rather, it is worth looking briefly at what lies behind the Hiroshima analogy.

Framing is political

In their classic paper Framing Theory, Chong and Druckman explain that the way an issue is presented, or ‘framed’, can work by “making certain available beliefs applicable or ‘strong’ in people’s evaluations” (p.110). So atomic bombs are a well-known concept, and provide a shortcut to ‘lay’ publics’ understanding the heat retention issue without any knowledge of the science: it invokes the notion of imminent catastrophe (what could be more catastrophic than an atomic bomb?!).

As such, it *is* scary  – although Nuccitelli and Cook claim “it isn’t used because it’s scary, it’s simply about communicating the sheer amount of heat our planet is accumulating”. Even if the effect was unintentional, linking climate change to Hiroshima fits with a pattern of actors in the political debate using what Glynos and Howarth call “horrific logics” (see pp.11-12 for an introduction) in an attempt to make a particular policy idea “grip” the public. Imminent catastrophes have been used by both advocates and sceptics: for example, the notion that we have only “100 months to save our climate” or that a pro-renewables policy will lead to the countryside being ‘carpeted’ in wind turbines.

In addition, Hiroshima emphasises the man-made nature of climate change, a constant theme of climate change communicators keen to debunk the idea that natural variability in climate is more significant than the contribution from increases in carbon emissions. So even though the Tōhoku earthquake/tsunami of 2011 is a far more recent catastrophe than Hiroshima, using it to communicate energy flows would risk implying that climate change is a natural, rather than a man-made, phenomenon. In addition, Tōhoku released around 580 million times more energy than one Hiroshima bomb. So one could choose to say that the heat being retained is equivalent to a Tōhoku every four and a half years. It’s no less accurate in communicating units of energy, but maybe that doesn’t sound quite as scary as four Hiroshimas per second…

The window test

So without disputing the science behind the Hiroshima meme, one can see that the choice of *that particular* unit of comparison to communicate energy retention is a political one, framing the climate change problem as both man-made and catastrophic. However, the ever-present challenge in communicating climate change remains what one might call ‘the window test’. That is, there is a gargantuan gap between the rhetoric of four Hiroshima bombs per second and what I can perceive looking out of my window. Looking out of my window for evidence may be highly unscientific, but it is a response one might expect when talking about a risk which is un-situated in time and space in catastrophic terms.

So rather than being an effective communications strategy, framing climate change in catastrophic terms may generate more heat than light, and has the potential to reduce public support for policy in the absence of material evidence of catastrophes. If four Hiroshimas per second result only in an intangible, incremental risk, rather than an *actual* catastrophe equivalent to Hiroshima, one might reach the opposite conclusion from that intended: that the earth is actually quite resilient to such energy retention, and that four Hiroshimas per second isn’t anything to worry about. This would not be a good outcome for advocates of climate change mitigation policies.

So perhaps a less sensational means of communication might be more effective. One candidate is the idea of the atmosphere as a bathtub, that is gradually being filled up by carbon emissions. One can argue about how big the bathtub is, the rate at which it is filling, and what happens when it overflows. However it does more effectively communicate the nuances of the potential effects of climate change, and the incrementally increasing risk, rather than the context-free, catastrophic climate porn of the Hiroshima meme.


Posted in Climate ChangeMetaphorsScience Communication