In his usual fashion, Anthony Watts decides it's rubbish as he does almost every peer-reviewed publication that touches on climate. This time he quotes another science denier associated with right wing lobby groups, Dr Indur Goklany. Dr Goklany decides that since homicides in the USA have been on the decline that is sufficient to say that climate change has no impact on human conflict.
Spot the fallacyThe fallacy is easy to spot. What it boils down to is the flawed argument that because other factors may influence the level of conflict therefore climate change cannot influence the level of conflict. (Note also that this argument, flawed though it is, assumes that the USA is experiencing climate change, which many deniers on WUWT don't accept.)
These people wouldn't do too well at Newtonian physics and would probably have some difficulty driving a motor vehicle. (They'd argue that a light touch of the brakes won't stop the car moving forward so why bother with the brake pedal at all.)
To determine whether or not climate change is having an influence in different parts of the USA would require looking at the change in each part of the USA that has undergone significant (1σ or greater) climate change, then eliminating other factors that influence rates of violence. Looking at the USA overall would just as likely mask the changes in individual locales.
Climatic events may alter individuals' ability to reason...I see in the comments that Anthony claims:
August 2, 2013 at 7:50 pm I care about data.Yet there is no indication that Anthony has bothered to read the paper in question or that he has looked at the underlying data. Lots of people say they "care" about stuff but don't do anything about it. I expect he'd say he "cares" about climate too. But when has he ever taken the time to understand it?
I wonder if this suggestion from the paper applies here:
For instance, climatic events may alter individuals' ability to reason and correctly interpret events (27, 28, 30, 31, 34–36), possibly leading to conflicts triggered by misunderstandings.There is only one person in the comments who says he has read the paper, and that's Willis Eschenbach. He writes that the paper is about weather not climate and that it contradicts what Anthony and Dr Goklany try to tell deniers. Willis Eschenbach says (extract):
August 2, 2013 at 9:06 pm ...The study actually says nothing about climate per se, just about the effects of weather calamities that they mistakenly describe as “climate”. I know that you will all be shocked to find out that when the weather goes bad, violence goes up...
From the conclusion
This is an extract from the conclusion of the paper:
Findings from a growing corpus of rigorous quantitative research across multiple disciplines suggest that past climatic events have exerted significant influence on human conflict. This influence appears to extend across the world, throughout history, and at all scales of social organization. We do not conclude that climate is the sole - or even primary - driving force in conflict, but we do find that when large climate variations occur, they can have substantial effects on the incidence of conflict across a variety of contexts. The median effect of a 1σ change in climate variables generates an 14% change in the risk of intergroup conflict and a 4% change in interpersonal violence, across the studies that we review where it is possible to calculate standardized effects. If future populations respond similarly to past populations, then anthropogenic climate change has the potential to substantially increase conflict around the world, relative to a world without climate change.
Although there is remarkable convergence of quantitative findings across disciplines, many open questions remain. Existing research has successfully established a causal relationship between climate and conflict but is unable to fully explain the mechanisms....
Climate or weatherThe paper is not easy to read. I'll have to do so several more times to get the most from it. Willis is correct to some extent that much of the work it cites is about weather, such as this:
Some forms of intergroup violence, such as Hindu-Muslim riots (Fig. 2D), tend to be more likely following extreme rainfall conditions (44–47). This relationship between intergroup violence and rainfall is primarily documented in low-income settings, suggesting that reduced agricultural production may be an important mediating mechanism - although alternative explanations cannot be excluded.But in other sections it is clearly about a change in climate, such as:
Under sufficiently high levels of climatological stress, pre-existing social institutions may strain beyond recovery and lead to major changes in governing institutions (77–79) (Fig. 3C), a process that often involves the forcible removal of rulers. High levels of climatological stress have also led to major changes in settlement patterns and social organization (80, 81) (Fig. 3D). Finally, in extreme cases, entire communities, civilizations and empires collapse entirely following large changes in climatic conditions (62, 79, 80, 82–89) (Fig. 3, A to C, E, and F). These documented catastrophic failures all precede the twentieth century, yet the level of economic development in these communities at the time of their collapse was similar to the level of development in many poor countries of the modern world [see (26) for a comparison], an indicator that these historical cases may continue to have modern relevance.
Here is Fig 3 (click for larger version)
The new question: What causes the relationship between climate and conflict?
ScienceDaily provides an overview of the study. Here is part:
Establishing a correlation between violence and climate change now allows policymakers and researchers to examine what causes it and how to intervene, said lead author Solomon Hsiang, who conducted the work as a postdoctoral research associate in the Program in Science, Technology and Environmental Policy in Princeton's Woodrow Wilson School of Public and International Affairs.
"We think that by collecting all the research together now, we're pretty clearly establishing that there is a causal relationship between the climate and human conflict," Hsiang said. "People have been skeptical up to now of an individual study here or there. But considering the body of work together, we can now show that these patterns are extremely general. It's more of the rule than the exception.
"Whether there is a relationship between climate and conflict is not the question anymore. We now want to understand what's causing it," Hsiang said. "Once we understand what causes this correlation we can think about designing effective policies or institutions to manage or interrupt the link between climate and conflict."
The existing research had essentially shown an overall link between climate conditions and these conflicts, but that link needed to be extracted from reams of figures from various disciplines in order for the research to reach general conclusions, Hsiang said. Hsiang, who is now an assistant professor at Berkeley's Goldman School of Public Policy, worked with co-first author Marshall Burke, a doctoral candidate in Berkeley's Department of Agricultural and Resource Economics, and Edward Miguel, the Oxfam Professor of Environmental and Resource Economics at Berkeley.
Some hypotheses on why climate change leads to conflict
Here is a summary of what the authors describe as having the strongest empirical support in existing analyses, although they state that the evidence is still often inconclusive:
- Climate change leads to a decline in local economic conditions. When climatic events cause economic productivity to decline, the value of engaging in conflict is likely to rise relative to the value of participating in normal economic activities.
- Climatic events result in actual or perceived inequalities. This could increase conflict by motivating attempts to redistribute assets.
- Climate change leads to mass migration or rapid urbanisation leading to conflicts over geographically stationary resources that are unrelated to the climate (119) but become relatively scarce where populations concentrate.
- Changes in climate might also affect the logistics of human conflict (76, 120), for example by altering the physical environment (e.g., road quality) in which disputes or violence might occur.
- Climate anomalies might result in conflict because they can make cognition and attribution more difficult or error-prone, or they many affect aggression through some physiological mechanism. For instance, climatic events may alter individuals' ability to reason and correctly interpret events (27, 28, 30, 31, 34–36), possibly leading to conflicts triggered by misunderstandings. Alternatively, if climatic changes and their economic consequences are inaccurately attributed to the actions of an individual or group (63, 122–125), for example an inept political leader (71), this may lead to violent actions that try to return economic conditions to normal by removing the “offending” population.
Back to the deniers
Typically, deniers at WUWT aren't interested in exploring the question. They simply want to deny that climates are changing. Some of them do, in any case. Others just want to argue that having more people with more guns to shoot each other leads to fewer people shooting each other. While a few of them argue that weather does have an impact on violence and unrest - either directly or indirectly.
August 2, 2013 at 7:54 pm Data: There are more than 300 million personal firearms in the USA. More guns equals less crime. Who would have thunk it?
August 2, 2013 at 7:55 pm Anthony, I wonder if you or anyone else has read the actual study or if it’s paywalled? I can’t help but wonder if they bothered to look at how COLD (and for that matter, drought) affects violence too, or if they only looked at warmth and increased rain…. and all things considered, somehow I wouldn’t be the least bit surprised if few or none of their 60 studies even considered the flip side… or the authors ignored it. I’d love to know.
Rational Db8 might be surprised, because Fig 3 as shown above includes temperature (cold and hot), drought and changes in precipitation and compares them with "periods of substantial social instability, violent conflict, or the breakdown of political institutions".
Theo Goodwin says:
August 2, 2013 at 8:21 pm Surely, their hypothesis was not that a warmer climate causes an increase in violence. If that were the claim then anyone who has moved from Missouri to Florida should be able to testify that it is false. Surely, the claim was that experiencing a warming climate while staying put causes an increase in violence. One problem with that claim is that no one has done it, except in the fantasies of Alarmists. There are many other problems. Suppose that the effects of a warming climate are easy to avoid? And so on. The authors are no doubt wearing those Groucho Marx masks.The authors address your argument, Theo. And many others besides. For example they write:
In an ideal experiment, we would observe two identical populations, change the climate of one, and observe whether this “treatment” lead to more or less conflict relative to the “control” conditions. Because the climate cannot be experimentally manipulated, researchers primarily rely on natural experiments where a given population is compared to itself at different moments in time when it is exposed to different climatic conditions - conditions which are exogenously determined by the climate system (9, 15). In this research design, a single population serves as both the “control” population - e.g., just before a change in climatic conditions- and the “treatment” population - e.g., just after a change in climatic conditions. Inferences are thus based only on how a fixed population responds to different climatic conditions which vary over time, and time-series or longitudinal analysis is used to construct a credible estimate for the causal effect of climate on conflict (12, 15, 16).There is too much stupid to choose from in the WUWT comments, but I'll leave you with this from Gunga Din who says:
August 3, 2013 at 8:32 am Did any of these temperature/crime studies account for the availability of air conditioning?Perhaps not so stupid, when you think about it. Ownership of air-conditioners would be related to economic prosperity, which would be inversely correlated with civil unrest and violence.
Science DOI: 10.1126/science.1235367