Paper Claims Surprisingly Strong Link Between Climate Change And Violence. Nonsense.

The official numbers
The official numbers

When does more crime happen, in winter or summer? Why? Too easy. How about this one: according to the FBI, what was the violent crime rate over time? No need to guess. It’s pictured above. The per capita all violent crime percent from 1960 to 2012 (the last year available). Looks to be coming down some since 1991, wouldn’t you say? (The plots for other crime types, including gun crimes, all have the same general shape.)

Say, isn’t the time range of this plot the period where the our-of-control global warming “climate catastrophe” began in earnest? Let’s look at what NOAA’s GISS says:

The official numbers

I’m not in the least interested in arguing about this data; for the sake of argument, let’s just accept it as it is. Look, however, only at the black dots, which are the actual data. The red line is a smoother, i.e. a model, and is not what happened. The model is not the data! Don’t smooth your time series data! (Look here and here for why.)

Let’s tie it all together. Does it look to you like climate change is “correlated” with the violent crime rate? If you’re Chris Mooney or an academic hot for a sensational paper or a member of the media anxious to signal your cooperation with government, you must say yes. Us ordinary folk, not addled by ideology, will say no.

The Washington Post put up yet another fantasy of Mooney’s entitled “There’s a surprisingly strong link between climate change and violence“. I don’t mean to be snarky, I really don’t. But this guy routinely provokes me beyond my ability to resist. May the Lord forgive me.

Mooney cites some new meta analysis, a study I’ll dissect in due course, “of the existing research examining the relationship between climate change and violence and conflict.” Here’s the meat:

Climate variables considered in these papers included temperature increases as well as drought and rainfall changes. Conflict was analyzed in terms of clashes between individuals (like fistfights) and fights between groups (like wars). After taking it all in, the authors found compelling evidence of a link between changes in temperature and increases in conflict, noting that “deviations from moderate temperatures and precipitation patterns systematically increase the risk of conflict, often substantially, with average effects that are highly statistically significant.” Bottom line: In an ever warming world, expect more wars, civil unrest, and strife, and also more violent crime in general.

Yes, that makes sense. A statistical model which analyzes simultaneously fist fights and wars. Almost as sensible as measuring how eight-year-olds spend their allowance and the machinations of the World Bank. Hey! It’s science!

The lesson is: never ever not ever never never believe a meta analysis at its face value. It is one of the most abused statistical techniques. Smoothing time series data is another. Never mind.

Mooney gets one thing partly right when he asks, “Why do hotter temperatures produce more violence?” The obvious answer—as long as we factor out all modern wars, many of which inconveniently occur in winter; in olden days, winter made it difficult to fight; who could have guessed?—is the one we started this post with. People are out in the summer’s long warm days, and inside in the winter’s short cold days. Easy.

Yet not so easy for Mooney and for academics for whom the obvious is never good enough.

Now I would have ignored the article, putting it down as yet another attempt to prove our lying eyes aren’t seeing what they’re seeing (the two graphs above). But Mooney had to go and mention baseball. (I’m a Tigers fan. I don’t want to talk about it.) Mooney thinks a paper he uncovered is terrific proof that climate change makes us more violent.

He quotes from the awful peer-reviewed paper “Temper, Temperature, and Temptation: Heat-Related Retaliation in Baseball” in Psychological Science (2011; 22(4) 423­–428) by Richard P. Larrick and some others. Larrick checked whether increasing temperatures were associated with more beanballs. The authors admitted they were not.

So, their theory busted but still desiring a paper, the authors had to try something else. How about retaliation? Do increasing temperatures cause more? Mooney shows a graph from their paper which is so silly that I refuse to picture it. He presents this graph, as do the authors, as if it were data. Which it is not. It is the output from a preposterously complex regression model (they “control” for 13 things!).

Baseball fans: when do more beanballs, and hence more retaliations take place, in chilly April when the season has just begun and all are of good cheer, or late in hot August when tempers are up and when games start to feel a lot more crucial? Is the observed discrepancy therefore caused by climate change?

Good grief, what a rotten paper, what a rotten theory.


  1. “Almost as sensible as measuring how eight-year-olds spend their allowance and the machinations of the World Bank.” Well said. The tried and true method of inflating statistics is to water down the definitions as far as possible. In the case of sexual assault, patting a women on the behind is now equivalent to rape, unless by some miracle, you get statistics that actually list the offenses.

    Has anyone studied the “self-fulfilling prophecy” affect of these studies? First we tell people global warming is real, then we tell them it makes them violent, then we shut off the power, and Whoa! We have all out violence. Surprise!!!!

    (Still working on shutting off the power, but I have faith the EPA will yet accomplish this.)

  2. Why YES, Briggs

    Look at the criminal blips on the crime statistics for 1980 and 1991.
    and then…
    Look at the criminal blips on the temp statistics for 1980 and 1991 (well close enough).

    It’s quite obvious those blips line up perfectly (what is that like r^2 = .99?)

    Be grateful that they didn’t smooth the crime statistics.

  3. The blips on 2005 line up as well

    Don’t know how it could be any clearer.

    As for the rape statistics, they’re very much underreported…
    (it’s almost like THEY actually read the Bible)
    “You’ve heard it said “Thou shalt not commit rape”
    I say …”

  4. Why is it taken for granted that per capita is the best way to display the data? This in itself implies certain assumptions such as that the crime bug strikes individuals at random in the population or possibly that victims are chosen at random. If this is not the case a rise in population may either suppress or enhance the per capita rate depending on the nature of the increase. At the very least the base population used to normalize the data should be restricted to the age group most likely to engage in violence. No doubt other categories can be imagined by the reader that would help to see if the criminal class is either increasing (decreasing) and/or becoming more (less) violent and not to forget the effect of incarcination. Analysis of real data in all its manifestations is a lot more useful than model building based on one method of presentation and more likely to lead to useful strategies.

  5. Scotian,

    Here’s the raw data.

    FBI all violent crime by year

    Though I argue some sort of consideration of population is important.

    Update: Oops. I originally forgot to take out the “100*” multiplier. Fixed.

    Update: I see that the y-axis is mislabeled. Boneheaded error. I’ll fix this afternoon. Meanwhile, mentally remove “Percent”.

  6. There ‘s also a very strong relationship between the number of witch trials and colder weather. This shows that the climate get colder as the number of witch burnings go up.

    So, don’t be angry with the believers for the way they treated us sceptics! They were just trying to cool the climate by burning heretics.

  7. Briggs, “Though I argue some sort of consideration of population is important.”

    So do I, but the question is which population? Total population is a poor choice. Would anyone list the rate of teenage pregnancy to the whole population? Even the whole teenage population would be incorrect. I think that a similar degree of intelligence should be shown for crime stats.

  8. Scotian

    Since we’re talking about the link of Global Warming to Violence
    You have to look at the population that is affected by Global Warming (by definition, everybody).

    It may very well be that older vulnerable people will commit even less crime that they might otherwise have in cooler less oppressive climate.
    It might be that older vulnerable people might commit more murder/suicides to mitigate further suffering to themselves and loved ones. Who knows? Who cares?

    This is a GLOBAL WARMING study – we’re looking at Anthropogenic violence – ANTHROPOGENIC GLOBAL WARMING overwhelms all of those other “natural variations” in violence. We’re just trying to come up with a “sensitivity” / “multiplying” effect Global Warming has on Violence.

    Even if we find a negative impact on violence by Global Warming, that should probably be ignored or tipped upside down so that the proper attribution is made.

    Sorry to be so brutal and verbally violent; it’s this darn Global Warming!

  9. Actually Violence itself needs to be examined under the hot glare of Global Warming. While accidentally falling off a cliff will likely result in a rather violent death, it might be considered ‘natural variation’ or ‘natural selection’ and not a crime (unless you were accidentally pushed on purpose). But with Global Warming, that event may have been compounded by the fact that you were hot and disoriented by Global Warming with the Koch Brothers culpable for your death.

    Any death by extreme weather events should now by categorized as Anthropogenic Violent Crime.

    A bull hot and tired in the field from servicing too many cows gores you in protest of working conditions. Anthropogenic Violent Crime.

    There’s a blade and a tipping point in your near future!

  10. The article follows, “This begs the question …” with a question. With such a display of ignorance it should be ignored.

  11. Ben Bradley must be rolling over in his grave, wondering how the editors allowed this one into the WAPO. It is a dark period for science and journalism when studies, articles, and headlines like those can be written.

  12. I tend to think climate change in general could indeed be related to violence. For example, I read that cooler climate led to “barbarian” tribes from Asia and Eastern Europe to invade the Roman empire. The cooler climate had reduced their crops and thinned their herds to such an extent they had to migrate elsewhere.

    However, I suspect population growth as well as depletion of natural resources could lead to growing violence. Therefore the issue is up in the air. I don´t think the use of USA crime figures, nor the paper´s arguments really tell the full story.

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